@article{
 title = {Look Up: Probing the Vertical Profile of New Particle Formation and Growth in the Planetary Boundary Layer with Models and Observations},
 type = {article},
 year = {2023},
 keywords = {NPF,SOA,mixed layer,new particle formation,nucleation,planetary boundary layer},
 pages = {e2022JD037525},
 volume = {n/a},
 websites = {https://doi.org/10.1029/2022JD037525},
 month = {1},
 publisher = {John Wiley & Sons, Ltd},
 day = {20},
 id = {e990969d-e2a4-382b-825f-9017c7e89fda},
 created = {2023-01-31T22:46:12.003Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:12.003Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 source_type = {JOUR},
 notes = {https://doi.org/10.1029/2022JD037525},
 private_publication = {false},
 abstract = {Abstract The processes of new particle formation (NPF) and growth are important contributors to cloud condensation nuclei (CCN) concentrations, and CCN are important for climate from their impact on planetary radiative forcing. While the general ubiquity and importance of NPF is understood, the vertical extent and governing mechanisms of NPF and growth in the lower troposphere are uncertain. We present an analysis of four NPF events and two non-NPF events during the HI-SCALE field campaign at the Southern Great Plains observatory in Oklahoma, USA. Firstly, we analyzed airborne and ground-based observations of aerosol and gas-phase properties. Secondly, we used a column aerosol chemistry and microphysics model to probe factors that influence the vertical profile of NPF. During HI-SCALE, we found several instances of enhanced NPF occurring several hundred meters above the surface; however, the spatio-temporal characteristics of the observed NPF made comparisons between airborne- and ground-based observations difficult. The model represented the observed NPF (or lack of NPF) and particle growth at the surface to final diameters within 10 nm. The model predicted enhanced NPF rates in the upper mixed layer, and this enhancement is primarily due to the temperature dependence in the NPF schemes, but this was also dependent on the vertical profile of gas-phase precursors measured during HI-SCALE. We found vertical mixing in the model either enhanced or suppressed NPF rates, aerosol number concentrations, and particle growth rates at the surface. Finally, our analysis provides insights for future field campaigns and modeling efforts investigating the vertical profile of NPF.},
 bibtype = {article},
 author = {O’Donnell, Samuel E and Akherati, Ali and He, Yicong and Hodshire, Anna L and Shilling, John E and Kuang, Chongai and Fast, Jerome D and Mei, Fan and Schobesberger7, Siegfried and Thornton, Joel A and Smith, James N and Jathar, Shantanu H and Pierce, Jeffrey R},
 doi = {https://doi.org/10.1029/2022JD037525},
 journal = {Journal of Geophysical Research: Atmospheres},
 number = {n/a}
}

Abstract The processes of new particle formation (NPF) and growth are important contributors to cloud condensation nuclei (CCN) concentrations, and CCN are important for climate from their impact on planetary radiative forcing. While the general ubiquity and importance of NPF is understood, the vertical extent and governing mechanisms of NPF and growth in the lower troposphere are uncertain. We present an analysis of four NPF events and two non-NPF events during the HI-SCALE field campaign at the Southern Great Plains observatory in Oklahoma, USA. Firstly, we analyzed airborne and ground-based observations of aerosol and gas-phase properties. Secondly, we used a column aerosol chemistry and microphysics model to probe factors that influence the vertical profile of NPF. During HI-SCALE, we found several instances of enhanced NPF occurring several hundred meters above the surface; however, the spatio-temporal characteristics of the observed NPF made comparisons between airborne- and ground-based observations difficult. The model represented the observed NPF (or lack of NPF) and particle growth at the surface to final diameters within 10 nm. The model predicted enhanced NPF rates in the upper mixed layer, and this enhancement is primarily due to the temperature dependence in the NPF schemes, but this was also dependent on the vertical profile of gas-phase precursors measured during HI-SCALE. We found vertical mixing in the model either enhanced or suppressed NPF rates, aerosol number concentrations, and particle growth rates at the surface. Finally, our analysis provides insights for future field campaigns and modeling efforts investigating the vertical profile of NPF.

@article{
 title = {Observations of gas-phase products from the nitrate-radical-initiated oxidation of four monoterpenes},
 type = {article},
 year = {2022},
 pages = {9017-9031},
 volume = {22},
 websites = {https://acp.copernicus.org/preprints/acp-2021-1020/,https://acp.copernicus.org/preprints/acp-2021-1020/acp-2021-1020.pdf},
 month = {1},
 publisher = {Copernicus Publications},
 day = {10},
 id = {8b1c9f8a-184a-3e3d-898a-7f57f6363bf5},
 created = {2022-06-30T18:35:11.136Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:18.421Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 source_type = {JOUR},
 private_publication = {false},
 abstract = {Chemical ionization mass spectrometry with the nitrate reagent ion (NO3- CIMS) was used to investigate the products of the nitrate radical (NO3) initiated oxidation of four monoterpenes in laboratory chamber experiments. α-Pinene, β-pinene, Δ-3-carene, and α-thujene were studied. The major gas-phase species produced in each system were distinctly different, showing the effect of monoterpene structure on the oxidation mechanism and further elucidating the contributions of these species to particle formation and growth. By comparing groupings of products based on the ratios of elements in the general formula CwHxNyOz, the relative importance of specific mechanistic pathways (fragmentation, termination, and radical rearrangement) can be assessed for each system. Additionally, the measured time series of the highly oxidized reaction products provide insights into the ratio of relative production and loss rates of the high-molecular-weight products of the Δ-3-carene system. The measured effective O:C ratios of reaction products were anticorrelated with new particle formation intensity and number concentration for each system; however, the monomer : dimer ratios of products had a small positive trend. Gas-phase yields of oxidation products measured by NO3- CIMS correlated with particle number concentrations for each monoterpene system, with the exception of α-thujene, which produced a considerable amount of low-volatility products but no particles. Species-resolved wall loss was measured with NO3- CIMS and found to be highly variable among oxidized reaction products in our stainless steel chamber.},
 bibtype = {article},
 author = {Dam, Michelia and Draper, Danielle C. and Marsavin, Andrey and Fry, Juliane L. and Smith, James N.},
 doi = {10.5194/acp-22-9017-2022},
 journal = {Atmospheric Chemistry and Physics},
 number = {13}
}

Chemical ionization mass spectrometry with the nitrate reagent ion (NO3- CIMS) was used to investigate the products of the nitrate radical (NO3) initiated oxidation of four monoterpenes in laboratory chamber experiments. α-Pinene, β-pinene, Δ-3-carene, and α-thujene were studied. The major gas-phase species produced in each system were distinctly different, showing the effect of monoterpene structure on the oxidation mechanism and further elucidating the contributions of these species to particle formation and growth. By comparing groupings of products based on the ratios of elements in the general formula CwHxNyOz, the relative importance of specific mechanistic pathways (fragmentation, termination, and radical rearrangement) can be assessed for each system. Additionally, the measured time series of the highly oxidized reaction products provide insights into the ratio of relative production and loss rates of the high-molecular-weight products of the Δ-3-carene system. The measured effective O:C ratios of reaction products were anticorrelated with new particle formation intensity and number concentration for each system; however, the monomer : dimer ratios of products had a small positive trend. Gas-phase yields of oxidation products measured by NO3- CIMS correlated with particle number concentrations for each monoterpene system, with the exception of α-thujene, which produced a considerable amount of low-volatility products but no particles. Species-resolved wall loss was measured with NO3- CIMS and found to be highly variable among oxidized reaction products in our stainless steel chamber.

@article{
 title = {Insufficient Condensable Organic Vapors Lead to Slow Growth of New Particles in an Urban Environment},
 type = {article},
 year = {2022},
 keywords = {high NOx,nanoparticle composition,new particle growth,oxygenated organic molecules,urban environments},
 pages = {9936-9946},
 volume = {56},
 id = {9e3d1694-d5b1-3111-8b4d-3a3b7763ab6f},
 created = {2023-01-11T22:48:15.124Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:17.611Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 source_type = {JOUR},
 private_publication = {false},
 abstract = {Atmospheric new particle formation significantly affects global climate and air quality after newly formed particles grow above ∼50 nm. In polluted urban atmospheres with 1-3 orders of magnitude higher new particle formation rates than those in clean atmospheres, particle growth rates are comparable or even lower for reasons that were previously unclear. Here, we address the slow growth in urban Beijing with advanced measurements of the size-resolved molecular composition of nanoparticles using the thermal desorption chemical ionization mass spectrometer and the gas precursors using the nitrate CI-APi-ToF. A particle growth model combining condensational growth and particle-phase acid-base chemistry was developed to explore the growth mechanisms. The composition of 8-40 nm particles during new particle formation events in urban Beijing is dominated by organics (∼80%) and sulfate (∼13%), and the remainder is from base compounds, nitrate, and chloride. With the increase in particle sizes, the fraction of sulfate decreases, while that of the slow-desorbed organics, organic acids, and nitrate increases. The simulated size-resolved composition and growth rates are consistent with the measured results in most cases, and they both indicate that the condensational growth of organic vapors and H2SO4 is the major growth pathway and the particle-phase acid-base reactions play a minor role. In comparison to the high concentrations of gaseous sulfuric acid and amines that cause high formation rates, the concentration of condensable organic vapors is comparably lower under the high NOx levels, while those of the relatively high-volatility nitrogen-containing oxidation products are higher. The insufficient condensable organic vapors lead to slow growth, which further causes low survival of the newly formed particles in urban environments. Thus, the low growth rates, to some extent, counteract the impact of the high formation rates on air quality and global climate in urban environments.},
 bibtype = {article},
 author = {Li, Xiaoxiao and Li, Yuyang and Cai, Runlong and Yan, Chao and Qiao, Xiaohui and Guo, Yishuo and Deng, Chenjuan and Yin, Rujing and Chen, Yijing and Li, Yiran and Yao, Lei and Sarnela, Nina and Zhang, Yusheng and Petäjä, Tuukka and Bianchi, Federico and Liu, Yongchun and Kulmala, Markku and Hao, Jiming and Smith, James N. and Jiang, Jingkun},
 doi = {10.1021/acs.est.2c01566},
 journal = {Environmental Science and Technology},
 number = {14}
}

Atmospheric new particle formation significantly affects global climate and air quality after newly formed particles grow above ∼50 nm. In polluted urban atmospheres with 1-3 orders of magnitude higher new particle formation rates than those in clean atmospheres, particle growth rates are comparable or even lower for reasons that were previously unclear. Here, we address the slow growth in urban Beijing with advanced measurements of the size-resolved molecular composition of nanoparticles using the thermal desorption chemical ionization mass spectrometer and the gas precursors using the nitrate CI-APi-ToF. A particle growth model combining condensational growth and particle-phase acid-base chemistry was developed to explore the growth mechanisms. The composition of 8-40 nm particles during new particle formation events in urban Beijing is dominated by organics (∼80%) and sulfate (∼13%), and the remainder is from base compounds, nitrate, and chloride. With the increase in particle sizes, the fraction of sulfate decreases, while that of the slow-desorbed organics, organic acids, and nitrate increases. The simulated size-resolved composition and growth rates are consistent with the measured results in most cases, and they both indicate that the condensational growth of organic vapors and H2SO4 is the major growth pathway and the particle-phase acid-base reactions play a minor role. In comparison to the high concentrations of gaseous sulfuric acid and amines that cause high formation rates, the concentration of condensable organic vapors is comparably lower under the high NOx levels, while those of the relatively high-volatility nitrogen-containing oxidation products are higher. The insufficient condensable organic vapors lead to slow growth, which further causes low survival of the newly formed particles in urban environments. Thus, the low growth rates, to some extent, counteract the impact of the high formation rates on air quality and global climate in urban environments.

@article{
 title = {Sulfuric acid in the Amazon basin: measurements and evaluation of existing sulfuric acid proxies},
 type = {article},
 year = {2022},
 pages = {10061-10076},
 volume = {22},
 id = {8495573c-4d42-3fdd-aadf-60e53859a523},
 created = {2023-01-31T22:46:13.028Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:13.028Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 source_type = {JOUR},
 private_publication = {false},
 abstract = {Sulfuric acid is a key contributor to new particle formation, though measurements of its gaseous concentrations are difficult to make. Several parameterizations to estimate sulfuric acid exist, all of which were constructed using measurements from the Northern Hemisphere. In this work, we report the first measurements of sulfuric acid from the Amazon basin. These measurements are consistent with concentrations measured in Hyytiälä, Finland, though, unlike Hyytiälä, there is no clear correlation of sulfuric acid with global radiation. There was a minimal difference in sulfuric acid observed between the wet and dry seasons in the Amazon basin. We also test the efficacy of existing proxies to estimate sulfuric acid in this region. Our results suggest that nighttime sulfuric acid production is due to both a stabilized Criegee intermediate pathway and oxidation of SO2 by OH, the latter of which is not currently accounted for in existing proxies. These results also illustrate the drawbacks of the common substitution of radiation for OH concentrations. None of the tested proxies effectively estimate sulfuric acid measurements at night. For estimates at all times of day, a recently published proxy based on data from the boreal forest should be used. If only daytime estimates are needed, several recent proxies that do not include the Criegee pathway are sufficient. More investigation of nighttime sulfuric acid production pathways is necessary to close the gap between measurements and estimates with existing proxies.},
 bibtype = {article},
 author = {Myers, Deanna C. and Kim, Saewung and Sjostedt, Steven and Guenther, Alex B. and Seco, Roger and Vega Bustillos, Oscar and Tota, Julio and Souza, Rodrigo A.F. and Smith, James N.},
 doi = {10.5194/acp-22-10061-2022},
 journal = {Atmospheric Chemistry and Physics},
 number = {15}
}

Sulfuric acid is a key contributor to new particle formation, though measurements of its gaseous concentrations are difficult to make. Several parameterizations to estimate sulfuric acid exist, all of which were constructed using measurements from the Northern Hemisphere. In this work, we report the first measurements of sulfuric acid from the Amazon basin. These measurements are consistent with concentrations measured in Hyytiälä, Finland, though, unlike Hyytiälä, there is no clear correlation of sulfuric acid with global radiation. There was a minimal difference in sulfuric acid observed between the wet and dry seasons in the Amazon basin. We also test the efficacy of existing proxies to estimate sulfuric acid in this region. Our results suggest that nighttime sulfuric acid production is due to both a stabilized Criegee intermediate pathway and oxidation of SO2 by OH, the latter of which is not currently accounted for in existing proxies. These results also illustrate the drawbacks of the common substitution of radiation for OH concentrations. None of the tested proxies effectively estimate sulfuric acid measurements at night. For estimates at all times of day, a recently published proxy based on data from the boreal forest should be used. If only daytime estimates are needed, several recent proxies that do not include the Criegee pathway are sufficient. More investigation of nighttime sulfuric acid production pathways is necessary to close the gap between measurements and estimates with existing proxies.

@article{
 title = {Volatility is the predictor for non-neutral acid to base ratio in nanoparticles smaller than 15 nm},
 type = {article},
 year = {2021},
 volume = {in prep.},
 id = {0f5f9cfb-5794-359a-80d1-c38620569cbe},
 created = {2021-01-17T15:22:31.414Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2021-08-18T20:59:21.234Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 private_publication = {false},
 bibtype = {article},
 author = {Chee, S. and Myllys, N. and Barsanti, K. C. and Smith, J. N.},
 journal = {Journal of Aerosol Science}
}

@article{
 title = {A predictive model for salt nanoparticle formation using heterodimer stability calculations},
 type = {article},
 year = {2021},
 pages = {11637-11654},
 volume = {21},
 id = {4c4f1a3f-d13d-3819-be49-5031b4a20954},
 created = {2021-01-17T15:22:31.790Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2021-12-15T15:07:25.936Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 private_publication = {false},
 abstract = {Acid-base clusters and stable salt formation are critical drivers of new particle formation events in the atmosphere. In this study, we explore salt heterodimer (a cluster of one acid and one base) stability as a function of gas-phase acidity, aqueous-phase acidity, heterodimer proton transference, vapor pressure, dipole moment and polarizability for salts comprised of sulfuric acid, methanesulfonic acid and nitric acid with nine bases. The best predictor of heterodimer stability was found to be gas-phase acidity. We then analyzed the relationship between heterodimer stability and J4×4, the theoretically predicted formation rate of a four-acid, four-base cluster, for sulfuric acid salts over a range of monomer concentrations from 105 to 109g molecg cm-3 and temperatures from 248 to 348g K and found that heterodimer stability forms a lognormal relationship with J4×4. However, temperature and concentration effects made it difficult to form a predictive expression of J4×4. In order to reduce those effects, heterodimer concentration was calculated from heterodimer stability and yielded an expression for predicting J4×4 for any salt, given approximately equal acid and base monomer concentrations and knowledge of monomer concentration and temperature. This parameterization was tested for the sulfuric acid-ammonia system by comparing the predicted values to experimental data and was found to be accurate within 2 orders of magnitude. We show that one can create a simple parameterization that incorporates the dependence on temperature and monomer concentration on J4×4 by defining a new term that we call the normalized heterodimer concentration, φ. A plot of J4×4 vs. φ collapses to a single monotonic curve for weak sulfate salts (difference in gas-phase acidity >95g kcalg mol-1) and can be used to accurately estimate J4×4 within 2 orders of magnitude in atmospheric models.},
 bibtype = {article},
 author = {Chee, Sabrina and Barsanti, Kelley and Smith, James N. and Myllys, Nanna},
 doi = {10.5194/acp-21-11637-2021},
 journal = {Atmospheric Chemistry and Physics},
 number = {15}
}

Acid-base clusters and stable salt formation are critical drivers of new particle formation events in the atmosphere. In this study, we explore salt heterodimer (a cluster of one acid and one base) stability as a function of gas-phase acidity, aqueous-phase acidity, heterodimer proton transference, vapor pressure, dipole moment and polarizability for salts comprised of sulfuric acid, methanesulfonic acid and nitric acid with nine bases. The best predictor of heterodimer stability was found to be gas-phase acidity. We then analyzed the relationship between heterodimer stability and J4×4, the theoretically predicted formation rate of a four-acid, four-base cluster, for sulfuric acid salts over a range of monomer concentrations from 105 to 109g molecg cm-3 and temperatures from 248 to 348g K and found that heterodimer stability forms a lognormal relationship with J4×4. However, temperature and concentration effects made it difficult to form a predictive expression of J4×4. In order to reduce those effects, heterodimer concentration was calculated from heterodimer stability and yielded an expression for predicting J4×4 for any salt, given approximately equal acid and base monomer concentrations and knowledge of monomer concentration and temperature. This parameterization was tested for the sulfuric acid-ammonia system by comparing the predicted values to experimental data and was found to be accurate within 2 orders of magnitude. We show that one can create a simple parameterization that incorporates the dependence on temperature and monomer concentration on J4×4 by defining a new term that we call the normalized heterodimer concentration, φ. A plot of J4×4 vs. φ collapses to a single monotonic curve for weak sulfate salts (difference in gas-phase acidity >95g kcalg mol-1) and can be used to accurately estimate J4×4 within 2 orders of magnitude in atmospheric models.

@article{
 title = {Composition of ultrafine particles in urban beijing: Measurement using a thermal desorption chemical ionization mass spectrometer},
 type = {article},
 year = {2021},
 keywords = {Mass spectrometer,Molecular composition,Semicontinuous,Ultrafine particles,Urban environment},
 pages = {2859-2868},
 volume = {55},
 month = {3},
 publisher = {AMER CHEMICAL SOC},
 city = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA},
 id = {c9c56e0d-bd09-3b26-b1e1-08273d3117a3},
 created = {2021-04-29T14:16:25.452Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2021-08-18T20:59:21.148Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {ISI:000626270400017},
 source_type = {article},
 user_context = {Article},
 private_publication = {false},
 abstract = {Ultrafine particles (UFPs) dominate the particle number population in the urban atmosphere and revealing their chemical composition is important. The thermal desorption chemical ionization mass spectrometer (TDCIMS) can semicontinuously measure UFP composition at the molecular level. We modified a TDCIMS and deployed it in urban Beijing. Radioactive materials in the TDCIMS for aerosol charging and chemical ionization were replaced by soft X-ray ionizers so that it can be operated in countries with tight regulations on radioactive materials. Protonated N-methyl-2-pyrrolidone ions were used as the positive reagent ion, which selectively detects ammonia and low-molecular weight-Aliphatic amines and amides vaporized from the particle phase. With superoxide as the negative reagent ion, a wide range of inorganic and organic compounds were observed, including nitrate, sulfate, aliphatic acids with carbon numbers up to 18, and highly oxygenated CHO, CHON, and CHOS compounds. The latter two can be attributed to parent ions or the decomposition products of organonitrates and organosulfates/organosulfonates, respectively. Components from both primary emissions and secondary formation of UFPs were identified. Compared to the UFPs measured at forest and marine sites, those in urban Beijing contain more nitrogen-containing and sulfur-containing compounds. These observations illustrate unique features of the UFPs in the urban environment and provide insights into their origins.},
 bibtype = {article},
 author = {Li, Xiaoxiao and Li, Yuyang and Lawler, Michael J. and Hao, Jiming and Smith, James N. and Jiang, Jingkun},
 doi = {10.1021/acs.est.0c06053},
 journal = {Environmental Science and Technology},
 number = {5}
}

Ultrafine particles (UFPs) dominate the particle number population in the urban atmosphere and revealing their chemical composition is important. The thermal desorption chemical ionization mass spectrometer (TDCIMS) can semicontinuously measure UFP composition at the molecular level. We modified a TDCIMS and deployed it in urban Beijing. Radioactive materials in the TDCIMS for aerosol charging and chemical ionization were replaced by soft X-ray ionizers so that it can be operated in countries with tight regulations on radioactive materials. Protonated N-methyl-2-pyrrolidone ions were used as the positive reagent ion, which selectively detects ammonia and low-molecular weight-Aliphatic amines and amides vaporized from the particle phase. With superoxide as the negative reagent ion, a wide range of inorganic and organic compounds were observed, including nitrate, sulfate, aliphatic acids with carbon numbers up to 18, and highly oxygenated CHO, CHON, and CHOS compounds. The latter two can be attributed to parent ions or the decomposition products of organonitrates and organosulfates/organosulfonates, respectively. Components from both primary emissions and secondary formation of UFPs were identified. Compared to the UFPs measured at forest and marine sites, those in urban Beijing contain more nitrogen-containing and sulfur-containing compounds. These observations illustrate unique features of the UFPs in the urban environment and provide insights into their origins.

@article{
 title = {Molecular properties affecting the hydration of acid–base clusters},
 type = {article},
 year = {2021},
 pages = {13106-13114},
 volume = {23},
 websites = {http://dx.doi.org/10.1039/D1CP01704G},
 publisher = {The Royal Society of Chemistry},
 id = {acd06724-3c5d-38c4-9f1f-85dd3c987fb9},
 created = {2021-12-15T15:07:25.142Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-11T22:58:58.025Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 source_type = {JOUR},
 private_publication = {false},
 abstract = {In the atmosphere, water in all phases is ubiquitous and plays important roles in catalyzing atmospheric chemical reactions, participating in cluster formation and affecting the composition of aerosol particles. Direct measurements of water-containing clusters are limited because water is likely to evaporate before detection, and therefore, theoretical tools are needed to study hydration in the atmosphere. We have studied thermodynamics and population dynamics of the hydration of different atmospherically relevant base monomers as well as sulfuric acid–base pairs. The hydration ability of a base seems to follow in the order of gas-phase base strength whereas hydration ability of acid–base pairs, and thus clusters, is related to the number of hydrogen binding sites. Proton transfer reactions at water–air interfaces are important in many environmental and biological systems, but a deeper understanding of their mechanisms remain elusive. By studying thermodynamics of proton transfer reactions in clusters containing up to 20 water molecules and a base molecule, we found that that the ability of a base to accept a proton in a water cluster is related to the aqueous-phase basicity. We also studied the second deprotonation reaction of a sulfuric acid in hydrated acid–base clusters and found that sulfate formation is most favorable in the presence of dimethylamine. Molecular properties related to the proton transfer ability in water clusters are discussed.},
 bibtype = {article},
 author = {Myllys, Nanna and Myers, Deanna and Chee, Sabrina and Smith, James N},
 doi = {10.1039/D1CP01704G},
 journal = {Physical Chemistry Chemical Physics},
 number = {23}
}

In the atmosphere, water in all phases is ubiquitous and plays important roles in catalyzing atmospheric chemical reactions, participating in cluster formation and affecting the composition of aerosol particles. Direct measurements of water-containing clusters are limited because water is likely to evaporate before detection, and therefore, theoretical tools are needed to study hydration in the atmosphere. We have studied thermodynamics and population dynamics of the hydration of different atmospherically relevant base monomers as well as sulfuric acid–base pairs. The hydration ability of a base seems to follow in the order of gas-phase base strength whereas hydration ability of acid–base pairs, and thus clusters, is related to the number of hydrogen binding sites. Proton transfer reactions at water–air interfaces are important in many environmental and biological systems, but a deeper understanding of their mechanisms remain elusive. By studying thermodynamics of proton transfer reactions in clusters containing up to 20 water molecules and a base molecule, we found that that the ability of a base to accept a proton in a water cluster is related to the aqueous-phase basicity. We also studied the second deprotonation reaction of a sulfuric acid in hydrated acid–base clusters and found that sulfate formation is most favorable in the presence of dimethylamine. Molecular properties related to the proton transfer ability in water clusters are discussed.

@article{
 title = {Indirect Measurements of the Composition of Ultrafine Particles in the Arctic Late-Winter},
 type = {article},
 year = {2021},
 keywords = {OASIS,Utqiagvik,new particle formation,ultrafine aerosol},
 volume = {126},
 id = {bcf8ca45-cb2a-3eba-bc5d-116f268b8301},
 created = {2023-01-31T22:46:14.387Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:14.387Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 source_type = {JOUR},
 private_publication = {false},
 abstract = {We present indirect measurements of size-resolved ultrafine particle composition conducted during the Ocean-Atmosphere-Sea Ice-Snowpack (OASIS) Campaign in Utqiagvik, Alaska, during March 2009. This study focuses on measurements of size-resolved particle hygroscopicity and volatility measured over two periods of the campaign. During a period that represents background conditions in this location, particle hygroscopic growth factors (HGF) at 90% relative humidity ranged from 1.45 to 1.51, which combined with volatility measurements suggest a mixture of ∼30% ammoniated sulfates and ∼70% oxidized organics. Two separate regional ultrafine particle growth events were also observed during this campaign. Event 1 coincided with elevated levels of H2SO4 and solar radiation. These particles were highly hygroscopic (HGF = 2.1 for 35 nm particles), but were almost fully volatilized at 160 °C. The air masses associated with both events originated over the Arctic Ocean. Event 1 was influenced by the upper marine boundary layer (200–350 m AGL), while Event 2 spent more time closer to the surface (50–150 m AGL) and over open ocean leads, suggesting marine influence in growth processes. Event 2 particles were slightly less hygroscopic (HGF = 1.94 for 35 nm and 1.67 for 15 nm particles), and similarly volatile. We hypothesize that particles formed during both events contained 60–70% hygroscopic salts by volume, with the balance for Event 1 being sulfates and oxidized organics for Event 2. These observations suggest that primary sea spray may be an important initiator of ultrafine particle formation events in the Arctic late-winter, but a variety of processes may be responsible for condensational growth.},
 bibtype = {article},
 author = {Myers, Deanna C and Lawler, Michael J and Mauldin, Roy L and Sjostedt, Steven and Dubey, Manvendra and Abbatt, Jonathan and Smith, James N},
 doi = {10.1029/2021JD035428},
 journal = {Journal of Geophysical Research: Atmospheres},
 number = {22}
}

We present indirect measurements of size-resolved ultrafine particle composition conducted during the Ocean-Atmosphere-Sea Ice-Snowpack (OASIS) Campaign in Utqiagvik, Alaska, during March 2009. This study focuses on measurements of size-resolved particle hygroscopicity and volatility measured over two periods of the campaign. During a period that represents background conditions in this location, particle hygroscopic growth factors (HGF) at 90% relative humidity ranged from 1.45 to 1.51, which combined with volatility measurements suggest a mixture of ∼30% ammoniated sulfates and ∼70% oxidized organics. Two separate regional ultrafine particle growth events were also observed during this campaign. Event 1 coincided with elevated levels of H2SO4 and solar radiation. These particles were highly hygroscopic (HGF = 2.1 for 35 nm particles), but were almost fully volatilized at 160 °C. The air masses associated with both events originated over the Arctic Ocean. Event 1 was influenced by the upper marine boundary layer (200–350 m AGL), while Event 2 spent more time closer to the surface (50–150 m AGL) and over open ocean leads, suggesting marine influence in growth processes. Event 2 particles were slightly less hygroscopic (HGF = 1.94 for 35 nm and 1.67 for 15 nm particles), and similarly volatile. We hypothesize that particles formed during both events contained 60–70% hygroscopic salts by volume, with the balance for Event 1 being sulfates and oxidized organics for Event 2. These observations suggest that primary sea spray may be an important initiator of ultrafine particle formation events in the Arctic late-winter, but a variety of processes may be responsible for condensational growth.

@article{
 title = {Atmospheric clusters to nanoparticles: Recent progress and challenges in closing the gap in chemical composition},
 type = {article},
 year = {2021},
 keywords = {Aerosol nanocluster,Nanoparticle composition,New particle formation,Nucleation},
 pages = {105733},
 volume = {153},
 websites = {http://www.sciencedirect.com/science/article/pii/S0021850220302184},
 id = {457f349f-1b4c-37a7-9ac4-8ca580c7998e},
 created = {2023-01-31T22:46:15.229Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:15.229Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Smith2021},
 source_type = {JOUR},
 private_publication = {false},
 abstract = {Aerosol nanoclusters (AN), defined here as molecular aggregates suspended in a gas with dimensions between 2 and 10 nm, are the link between substances that we think of as molecules, or the “gas phase,” and those that we consider as particles, or the “condensed phase.” The ability to measure and model the physical and chemical properties of size-resolved AN, which at present is rudimentary at best, is crucial for understanding how particles form and evolve in a number of environments that are natural or influenced by human activities. This review describes the current state-of-the-art for measuring and modeling the size-resolved composition of atmospheric AN. We focus specifically on instruments, many relying on mass spectrometry, that show promise for closing the measurement gap under atmospherically relevant conditions by increasing the size of measurable gas-phase clusters (bottom-up approaches) and by decreasing the size of measurable nanoparticles (top-down approaches). Theoretical methods for predicting AN composition have similarly relied on bottom-up approaches that extend the accuracy of quantum chemistry calculations to larger molecular systems, as well as top-down approaches that correct bulk composition aerosol models for size-dependent properties such as viscosity and volatility. Current measurement and modeling challenges that must be overcome in order to close the gap are discussed.},
 bibtype = {article},
 author = {Smith, James N. and Draper, Danielle C. and Chee, Sabrina and Dam, Michelia and Glicker, Hayley and Myers, Deanna and Thomas, Adam E. and Lawler, Michael J. and Myllys, Nanna},
 doi = {10.1016/j.jaerosci.2020.105733},
 journal = {Journal of Aerosol Science}
}

Aerosol nanoclusters (AN), defined here as molecular aggregates suspended in a gas with dimensions between 2 and 10 nm, are the link between substances that we think of as molecules, or the “gas phase,” and those that we consider as particles, or the “condensed phase.” The ability to measure and model the physical and chemical properties of size-resolved AN, which at present is rudimentary at best, is crucial for understanding how particles form and evolve in a number of environments that are natural or influenced by human activities. This review describes the current state-of-the-art for measuring and modeling the size-resolved composition of atmospheric AN. We focus specifically on instruments, many relying on mass spectrometry, that show promise for closing the measurement gap under atmospherically relevant conditions by increasing the size of measurable gas-phase clusters (bottom-up approaches) and by decreasing the size of measurable nanoparticles (top-down approaches). Theoretical methods for predicting AN composition have similarly relied on bottom-up approaches that extend the accuracy of quantum chemistry calculations to larger molecular systems, as well as top-down approaches that correct bulk composition aerosol models for size-dependent properties such as viscosity and volatility. Current measurement and modeling challenges that must be overcome in order to close the gap are discussed.

@article{
 title = {Novel ionization reagent for the measurement of gas-phase ammonia and amines using a stand-alone atmospheric pressure gas chromatography (APGC) source},
 type = {article},
 year = {2020},
 volume = {34},
 websites = {https://doi.org/10.1002/rcm.8561},
 month = {8},
 publisher = {John Wiley & Sons, Ltd},
 day = {19},
 id = {9895b8fb-1655-3e03-a206-53a4788c9271},
 created = {2019-10-10T18:23:40.417Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2021-08-18T20:59:20.946Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Perraud2019b},
 source_type = {JOUR},
 notes = {doi: 10.1002/rcm.8561},
 private_publication = {false},
 abstract = {Rationale: Contaminants present in ambient air or in sampling lines can interfere with the target analysis through overlapping peaks or causing a high background. This study presents a positive outcome from the unexpected presence of N-methyl-2-pyrrolidone, released from a PALL HEPA filter, in the analysis of atmospherically relevant gas-phase amines using chemical ionization mass spectrometry. Methods: Gas-phase measurements were performed using a triple quadrupole mass spectrometer equipped with a modified atmospheric pressure gas chromatography (APGC) source which allows sampling of the headspace above pure amine standards. Gas-phase N-methyl-2-pyrrolidone (NMP) emitted from a PALL HEPA filter located in the inlet stream served as the ionizing agent. Results: This study demonstrates that some alkylamines efficiently form a [NMP + amine+H]+ cluster with NMP upon chemical ionization at atmospheric pressure. The extent of cluster formation depends largely on the proton affinity of the amine compared with that of NMP. Aromatic amines (aniline, pyridine) and diamines (putrescine) were shown not to form cluster ions with NMP. Conclusions: The use of NMP as an ionizing agent with stand-alone APGC provided high sensitivity for ammonia and the smaller amines. The main advantages, in addition to sensitivity, are direct sampling into the APGC source and avoiding uptake on sampling lines which can be a significant problem with ammonia and amines.},
 bibtype = {article},
 author = {Perraud, Véronique and Li, Xiaoxiao and Smith, James N. and Finlayson-Pitts, Barbara J.},
 doi = {10.1002/rcm.8561},
 journal = {Rapid Communications in Mass Spectrometry},
 number = {10}
}

Rationale: Contaminants present in ambient air or in sampling lines can interfere with the target analysis through overlapping peaks or causing a high background. This study presents a positive outcome from the unexpected presence of N-methyl-2-pyrrolidone, released from a PALL HEPA filter, in the analysis of atmospherically relevant gas-phase amines using chemical ionization mass spectrometry. Methods: Gas-phase measurements were performed using a triple quadrupole mass spectrometer equipped with a modified atmospheric pressure gas chromatography (APGC) source which allows sampling of the headspace above pure amine standards. Gas-phase N-methyl-2-pyrrolidone (NMP) emitted from a PALL HEPA filter located in the inlet stream served as the ionizing agent. Results: This study demonstrates that some alkylamines efficiently form a [NMP + amine+H]+ cluster with NMP upon chemical ionization at atmospheric pressure. The extent of cluster formation depends largely on the proton affinity of the amine compared with that of NMP. Aromatic amines (aniline, pyridine) and diamines (putrescine) were shown not to form cluster ions with NMP. Conclusions: The use of NMP as an ionizing agent with stand-alone APGC provided high sensitivity for ammonia and the smaller amines. The main advantages, in addition to sensitivity, are direct sampling into the APGC source and avoiding uptake on sampling lines which can be a significant problem with ammonia and amines.

@article{
 title = {Atmospheric fungal nanoparticle bursts},
 type = {article},
 year = {2020},
 pages = {eaax9051},
 volume = {6},
 websites = {http://advances.sciencemag.org/content/6/3/eaax9051.abstract},
 month = {1},
 day = {1},
 id = {0697d17f-5a48-3269-b065-2d227274df25},
 created = {2020-01-21T19:51:14.916Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-08-21T23:00:48.508Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Lawler2020},
 source_type = {JOUR},
 private_publication = {false},
 abstract = {Aerosol nanoparticles play an important role in the climate system by affecting cloud formation and properties, as well as in human health because of their deep reach into lungs and the circulatory system. Determining nanoparticle sources and composition is a major challenge in assessing their impacts in these areas. The sudden appearance of large numbers of atmospheric nanoparticles is commonly attributed to secondary formation from gas-phase precursors, but in many cases, the evidence for this is equivocal. We report the detection of a mode of fungal fragments with a mobility diameter of roughly 30 nm released in episodic bursts in ambient air over an agricultural area in northern Oklahoma. These events reached concentrations orders of magnitude higher than other reports of biological particles and show similarities to unclarified events reported previously in the Amazon. These particles potentially represent a large source of both cloud-forming ice nuclei and respirable allergens in a variety of ecosystems.},
 bibtype = {article},
 author = {Lawler, Michael J. and Draper, Danielle C. and Smith, James N.},
 doi = {10.1126/sciadv.aax9051},
 journal = {Science Advances},
 number = {3}
}

Aerosol nanoparticles play an important role in the climate system by affecting cloud formation and properties, as well as in human health because of their deep reach into lungs and the circulatory system. Determining nanoparticle sources and composition is a major challenge in assessing their impacts in these areas. The sudden appearance of large numbers of atmospheric nanoparticles is commonly attributed to secondary formation from gas-phase precursors, but in many cases, the evidence for this is equivocal. We report the detection of a mode of fungal fragments with a mobility diameter of roughly 30 nm released in episodic bursts in ambient air over an agricultural area in northern Oklahoma. These events reached concentrations orders of magnitude higher than other reports of biological particles and show similarities to unclarified events reported previously in the Amazon. These particles potentially represent a large source of both cloud-forming ice nuclei and respirable allergens in a variety of ecosystems.

@article{
 title = {PTR-TOF-MS eddy covariance measurements of isoprene and monoterpene fluxes from an eastern Amazonian rainforest},
 type = {article},
 year = {2020},
 pages = {7179-7191},
 volume = {20},
 month = {6},
 id = {718ebc87-fd1b-3af3-a90a-8dae4afc6fda},
 created = {2020-08-21T20:38:12.913Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-11-12T23:38:02.066Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {ISI:000543687000002},
 source_type = {article},
 private_publication = {false},
 abstract = {Biogenic volatile organic compounds (BVOCs) are important components of the atmosphere due to their contribution to atmospheric chemistry and biogeochemical cycles. Tropical forests are the largest source of the dominant BVOC emissions (e.g. isoprene and monoterpenes). In this study, we report isoprene and total monoterpene flux measurements with a proton transfer reaction time-of-flight mass spectrometer (PTR-TOF-MS) using the eddy covariance (EC) method at the Tapajos National Forest (2.857 S, 54.959 W), a primary rainforest in eastern Amazonia. Measurements were carried out from 1 to 16 June 2014, during the wet-to-dry transition season. During the measurement period, the measured daytime (06:00- 18:00 LT) average isoprene mixing ratios and fluxes were 1:15-0:60 ppb and 0:55-0:71 mgCm-2 h-1, respectively, whereas the measured daytime average total monoterpene mixing ratios and fluxes were 0:14-0:10 ppb and 0:20- 0:25 mgCm-2 h-1, respectively. Midday (10:00-14:00 LT) average isoprene and total monoterpene mixing ratios were 1:70-0:49 and 0:24-0:05 ppb, respectively, whereas midday average isoprene and monoterpene fluxes were 1:24- 0:68 and 0:46-0:22 mgCm-2 h-1, respectively. Isoprene and total monoterpene emissions in Tapajos were correlated with ambient temperature and solar radiation. Significant correlation with sensible heat flux, SHF (r2 D 0:77), was also observed. Measured isoprene and monoterpene fluxes were strongly correlated with each other (r2 D 0:93). The MEGAN2.1 (Model of Emissions of Gases and Aerosols from Nature version 2.1) model could simulate most of the observed diurnal variations (r2 D 0:7 to 0.8) but declined a little later in the evening for both isoprene and total monoterpene fluxes. The results also demonstrate the importance of site-specific vegetation emission factors (EFs) for accurately simulating BVOC fluxes in regional and global BVOC emission models.},
 bibtype = {article},
 author = {Sarkar, Chinmoy and Guenther, Alex B. and Park, Jeong Hoo and Seco, Roger and Alves, Eliane and Batalha, Sarah and Santana, Raoni and Kim, Saewung and Smith, James and Tóta, Julio and Vega, Oscar},
 doi = {10.5194/acp-20-7179-2020},
 journal = {Atmospheric Chemistry and Physics},
 number = {12}
}

Biogenic volatile organic compounds (BVOCs) are important components of the atmosphere due to their contribution to atmospheric chemistry and biogeochemical cycles. Tropical forests are the largest source of the dominant BVOC emissions (e.g. isoprene and monoterpenes). In this study, we report isoprene and total monoterpene flux measurements with a proton transfer reaction time-of-flight mass spectrometer (PTR-TOF-MS) using the eddy covariance (EC) method at the Tapajos National Forest (2.857 S, 54.959 W), a primary rainforest in eastern Amazonia. Measurements were carried out from 1 to 16 June 2014, during the wet-to-dry transition season. During the measurement period, the measured daytime (06:00- 18:00 LT) average isoprene mixing ratios and fluxes were 1:15-0:60 ppb and 0:55-0:71 mgCm-2 h-1, respectively, whereas the measured daytime average total monoterpene mixing ratios and fluxes were 0:14-0:10 ppb and 0:20- 0:25 mgCm-2 h-1, respectively. Midday (10:00-14:00 LT) average isoprene and total monoterpene mixing ratios were 1:70-0:49 and 0:24-0:05 ppb, respectively, whereas midday average isoprene and monoterpene fluxes were 1:24- 0:68 and 0:46-0:22 mgCm-2 h-1, respectively. Isoprene and total monoterpene emissions in Tapajos were correlated with ambient temperature and solar radiation. Significant correlation with sensible heat flux, SHF (r2 D 0:77), was also observed. Measured isoprene and monoterpene fluxes were strongly correlated with each other (r2 D 0:93). The MEGAN2.1 (Model of Emissions of Gases and Aerosols from Nature version 2.1) model could simulate most of the observed diurnal variations (r2 D 0:7 to 0.8) but declined a little later in the evening for both isoprene and total monoterpene fluxes. The results also demonstrate the importance of site-specific vegetation emission factors (EFs) for accurately simulating BVOC fluxes in regional and global BVOC emission models.

@article{
 title = {Size-Resolved Chemical Composition of Sub-20 nm Particles from Methanesulfonic Acid Reactions with Methylamine and Ammonia},
 type = {article},
 year = {2020},
 keywords = {ammonia,methanesulfonic acid,methylamine,nanoparticles,new particle formation,thermal desorption chemical ionization mass spectr},
 pages = {1182-1194},
 volume = {4},
 websites = {https://doi.org/10.1021/acsearthspacechem.0c00120},
 month = {7},
 publisher = {American Chemical Society},
 day = {16},
 id = {31a55610-ad9b-327f-903b-5b872b21214f},
 created = {2020-09-02T22:07:51.477Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2021-12-15T15:07:26.199Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 source_type = {JOUR},
 notes = {doi: 10.1021/acsearthspacechem.0c00120},
 private_publication = {false},
 abstract = {Particle formation in the atmosphere from gas-phase precursors has been observed around the world; however, our fundamental understanding of the key species responsible and mechanisms involved remains uncertain. Recent laboratory studies demonstrated that acid-base reactions involving methanesulfonic acid (CH3SO3H, MSA) and small alkylamines may contribute significantly to new particle formation. To date, most of the investigations have been focused on particle number concentration and size distribution measurements in combination with quantum chemistry predictions of the most stable clusters. Here, we present the first measurements of the size-resolved chemical composition of sub-20 nm particles generated in a custom flow reactor from the reaction of MSA with methylamine (MA) in the presence or absence of NH3 using thermal desorption chemical ionization mass spectrometry (TDCIMS). A novel design of the TDCIMS inlet was evaluated, and the measurement of the chemical composition of particles was extended down to 5 nm in diameter, the smallest size yet reported for this method. MSA-MA particles with diameters smaller than 9 nm were found to be more acidic, with an acid/base molar ratio of 1.8 ± 0.4 (1σ) for 5 nm particles compared to the larger particles which were neutral. A similar acid/base molar ratio trend was observed when NH3 was added to the MSA-MA combination. In the MSA-MA-NH3 system, the MA/NH3 molar ratio was higher than 1 (up to 2.6) for all particle sizes despite the much larger concentration of NH3 in the gas phase (the gas-phase MA/NH3 ratio was ∼0.23), indicating that MA is a key component in particle formation from this system. The potential reasons for this based on previous calculations of small clusters in this system are discussed.},
 bibtype = {article},
 author = {Perraud, Véronique and Li, Xiaoxiao and Jiang, Jingkun and Finlayson-Pitts, Barbara J. and Smith, James N.},
 doi = {10.1021/acsearthspacechem.0c00120},
 journal = {ACS Earth and Space Chemistry},
 number = {7}
}

Particle formation in the atmosphere from gas-phase precursors has been observed around the world; however, our fundamental understanding of the key species responsible and mechanisms involved remains uncertain. Recent laboratory studies demonstrated that acid-base reactions involving methanesulfonic acid (CH3SO3H, MSA) and small alkylamines may contribute significantly to new particle formation. To date, most of the investigations have been focused on particle number concentration and size distribution measurements in combination with quantum chemistry predictions of the most stable clusters. Here, we present the first measurements of the size-resolved chemical composition of sub-20 nm particles generated in a custom flow reactor from the reaction of MSA with methylamine (MA) in the presence or absence of NH3 using thermal desorption chemical ionization mass spectrometry (TDCIMS). A novel design of the TDCIMS inlet was evaluated, and the measurement of the chemical composition of particles was extended down to 5 nm in diameter, the smallest size yet reported for this method. MSA-MA particles with diameters smaller than 9 nm were found to be more acidic, with an acid/base molar ratio of 1.8 ± 0.4 (1σ) for 5 nm particles compared to the larger particles which were neutral. A similar acid/base molar ratio trend was observed when NH3 was added to the MSA-MA combination. In the MSA-MA-NH3 system, the MA/NH3 molar ratio was higher than 1 (up to 2.6) for all particle sizes despite the much larger concentration of NH3 in the gas phase (the gas-phase MA/NH3 ratio was ∼0.23), indicating that MA is a key component in particle formation from this system. The potential reasons for this based on previous calculations of small clusters in this system are discussed.

@article{
 title = {Ab initio metadynamics calculations of dimethylamine for probing p K bvariations in bulk vs. surface environments},
 type = {article},
 year = {2020},
 pages = {26265-26277},
 volume = {22},
 month = {12},
 id = {2d7edca8-079e-3916-ae19-4bd529ffbca0},
 created = {2021-01-17T15:22:31.454Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2021-08-18T20:59:21.363Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {ISI:000592983900017},
 source_type = {article},
 private_publication = {false},
 abstract = {The basicity constant, or pKb, is an intrinsic physical property of bases that gives a measure of its proton affinity in macroscopic environments. While the pKb is typically defined in reference to the bulk aqueous phase, several studies have suggested that this value can differ significantly at the air-water interface (which can have significant ramifications for particle surface chemistry and aerosol growth modeling). To provide mechanistic insight into surface proton affinity, we carried out ab initio metadynamics calculations to (1) explore the free-energy profile of dimethylamine and (2) provide reasonable estimates of the pKb value in different solvent environments. We find that the free-energy profiles obtained with our metadynamics calculations show a dramatic variation, with interfacial aqueous dimethylamine pKb values being significantly lower than in the bulk aqueous environment. Furthermore, our metadynamics calculations indicate that these variations are due to reduced hydrogen bonding at the air-water surface. Taken together, our quantum mechanical metadynamics calculations show that the reactivity of dimethylamine is surprisingly complex, leading to pKb variations that critically depend on the different atomic interactions occurring at the microscopic molecular level. This journal is},
 bibtype = {article},
 author = {Biswas, Sohag and Kwon, Hyuna and Barsanti, Kelley C. and Myllys, Nanna and Smith, James N. and Wong, Bryan M.},
 doi = {10.1039/d0cp03832f},
 journal = {Physical Chemistry Chemical Physics},
 number = {45}
}

The basicity constant, or pKb, is an intrinsic physical property of bases that gives a measure of its proton affinity in macroscopic environments. While the pKb is typically defined in reference to the bulk aqueous phase, several studies have suggested that this value can differ significantly at the air-water interface (which can have significant ramifications for particle surface chemistry and aerosol growth modeling). To provide mechanistic insight into surface proton affinity, we carried out ab initio metadynamics calculations to (1) explore the free-energy profile of dimethylamine and (2) provide reasonable estimates of the pKb value in different solvent environments. We find that the free-energy profiles obtained with our metadynamics calculations show a dramatic variation, with interfacial aqueous dimethylamine pKb values being significantly lower than in the bulk aqueous environment. Furthermore, our metadynamics calculations indicate that these variations are due to reduced hydrogen bonding at the air-water surface. Taken together, our quantum mechanical metadynamics calculations show that the reactivity of dimethylamine is surprisingly complex, leading to pKb variations that critically depend on the different atomic interactions occurring at the microscopic molecular level. This journal is

@misc{
 title = {A sew-free origami mask for improvised respiratory protection},
 type = {misc},
 year = {2020},
 source = {medRxiv},
 id = {2dc00fe9-ade4-363f-baae-2b2178498fdb},
 created = {2021-02-05T23:59:00.000Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2021-08-18T20:37:56.566Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 private_publication = {true},
 abstract = {The copyright holder for this preprint is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license. Recently, respiratory aerosols with diameters smaller than 100 µm have been confirmed as important vectors for the spread of SARS-CoV-2. While cloth masks afford some protection for larger ballistic droplets, they are typically inefficient at filtering these aerosols and require specialized fabrication devices to produce. We describe a fabrication technique that makes use of a folding procedure (origami) to transform a filtration material into a mask. These origami masks can be fabricated by non-experts at minimal cost and effort, provide adequate filtration efficiencies, and are easily scaled to different facial sizes. Using a mannequin fit test simulator, we demonstrate that these masks can provide optimal filtration efficiency and ease of breathing with minimal leakage. Because this mask provides greater comfort compared to commercial alternatives, it is likely to promote greater mask wearing tolerance and acceptance.},
 bibtype = {misc},
 author = {Realmuto, J. and Kleinman, M.T. and Sanger, T. and Lawler, M.J. and Smith, J.N.},
 doi = {10.1101/2020.09.29.20204115}
}

The copyright holder for this preprint is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license. Recently, respiratory aerosols with diameters smaller than 100 µm have been confirmed as important vectors for the spread of SARS-CoV-2. While cloth masks afford some protection for larger ballistic droplets, they are typically inefficient at filtering these aerosols and require specialized fabrication devices to produce. We describe a fabrication technique that makes use of a folding procedure (origami) to transform a filtration material into a mask. These origami masks can be fabricated by non-experts at minimal cost and effort, provide adequate filtration efficiencies, and are easily scaled to different facial sizes. Using a mannequin fit test simulator, we demonstrate that these masks can provide optimal filtration efficiency and ease of breathing with minimal leakage. Because this mask provides greater comfort compared to commercial alternatives, it is likely to promote greater mask wearing tolerance and acceptance.

@article{
 title = {Comparison of aerosol measurement systems during the 2016 airborne ARISTO campaign},
 type = {article},
 year = {2019},
 pages = {871-885},
 volume = {53},
 id = {b0f3c301-bb9c-3da8-bcf9-b3dfe7a8659a},
 created = {2019-07-11T17:26:48.063Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-08-21T23:00:45.349Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Ortega2019},
 private_publication = {false},
 abstract = {Several different types of measurements of particle size and concentration were compared during the 2016 Airborne Research Instrumentation Testing Opportunity (ARISTO) campaign. The scanning mobility particle sizer (SMPS) measured number-size distributions for mobility diameters between ∼20–350 and ∼8–110 nm, depending on the mobility analyzer chosen. Also included were two stand-alone condensation particle counters (CPC) for determining size-integrated particle concentrations. A wing-mounted and a rack-mounted Ultra-High Sensitivity Aerosol Spectrometer (UHSAS) were used to measure size distributions between 60 and 1000 nm. Lastly, two different sampling inlets were used to investigate performance and observe any systematic biases. Most sampling occurred during cloud-free summer conditions in the western United States. Number concentrations from the two CPCs typically agreed within 12% once the flows in the ultrafine particle counter were corrected as a function of pressure. As expected, the size-integrated number concentrations from the SMPS and UHSAS were generally less than those of the CPCs, as the former cover only part of the total range of particle sizes measured by the CPCs. Integrated number concentrations from the wing-mounted and rack-mounted UHSAS generally agreed within 20% for all diameter ranges analyzed. The overlap region between the SMPS and the UHSAS showed reasonable agreement of ±20%. Some of the uncertainty regarding these measurement comparisons originates from a variety of factors, including sampling frequency, particle refractive index, differences between physical and mobility diameters, and counting efficiency uncertainties in the UHSAS optical cavity, especially for the smallest diameters (60–100 nm). Copyright © 2019 American Association for Aerosol Research.},
 bibtype = {article},
 author = {Ortega, John and Snider, Jefferson R. and Smith, James N. and Reeves, J. Michael},
 doi = {10.1080/02786826.2019.1610554},
 journal = {Aerosol Science and Technology},
 number = {8}
}

Several different types of measurements of particle size and concentration were compared during the 2016 Airborne Research Instrumentation Testing Opportunity (ARISTO) campaign. The scanning mobility particle sizer (SMPS) measured number-size distributions for mobility diameters between ∼20–350 and ∼8–110 nm, depending on the mobility analyzer chosen. Also included were two stand-alone condensation particle counters (CPC) for determining size-integrated particle concentrations. A wing-mounted and a rack-mounted Ultra-High Sensitivity Aerosol Spectrometer (UHSAS) were used to measure size distributions between 60 and 1000 nm. Lastly, two different sampling inlets were used to investigate performance and observe any systematic biases. Most sampling occurred during cloud-free summer conditions in the western United States. Number concentrations from the two CPCs typically agreed within 12% once the flows in the ultrafine particle counter were corrected as a function of pressure. As expected, the size-integrated number concentrations from the SMPS and UHSAS were generally less than those of the CPCs, as the former cover only part of the total range of particle sizes measured by the CPCs. Integrated number concentrations from the wing-mounted and rack-mounted UHSAS generally agreed within 20% for all diameter ranges analyzed. The overlap region between the SMPS and the UHSAS showed reasonable agreement of ±20%. Some of the uncertainty regarding these measurement comparisons originates from a variety of factors, including sampling frequency, particle refractive index, differences between physical and mobility diameters, and counting efficiency uncertainties in the UHSAS optical cavity, especially for the smallest diameters (60–100 nm). Copyright © 2019 American Association for Aerosol Research.

@article{
 title = {An Experimental and Modeling Study of Nanoparticle Formation and Growth from Dimethylamine and Nitric Acid},
 type = {article},
 year = {2019},
 pages = {5640-5648},
 volume = {123},
 id = {e0b6aeb7-7e44-3d94-9ed0-cc6405b6791a},
 created = {2019-07-11T17:26:48.098Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-08-21T23:00:45.375Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Chee2019},
 private_publication = {false},
 abstract = {The size-resolved composition of nanoparticles formed and grown through acid-base reactive uptake has been studied in the laboratory by reacting gas-phase nitric acid (HNO3) and dimethylamine (DMA) in a flow tube under dry (<5% RH) and humid (∼55% RH) conditions. Size-resolved nanoparticle composition was measured by a thermal desorption chemical ionization mass spectrometer over the diameter range of 9-30 nm. The nanoparticle geometric mean diameter grew in the presence of water compared to dry conditions. Acid/base ratios of HNO3-DMA particles at all measured sizes did not strongly deviate from neutral (1:1) in either RH condition, which contrasts with prior laboratory studies of nanoparticles made from sulfuric acid (H2SO4) and base. Theoretical methods were used to investigate the underlying chemical processes that explain observed differences in the compositions of HNO3-DMA and H2SO4-DMA particles. Calculations of HNO3-DMA cluster stability indicated that a 1:1 acid/base ratio has >107 smaller evaporation rates than any other acid/base ratio in this system, and measured nanoparticle composition confirm this to be the most stable pathway for growth up to 30 nm particles. This study demonstrates that nanoparticle formation and growth via acid-base reactive uptake of HNO3 and DMA follow the thermodynamic theory, likely because of both components' volatility.},
 bibtype = {article},
 author = {Chee, Sabrina and Myllys, Nanna and Barsanti, Kelley C. and Wong, Bryan M. and Smith, James N.},
 doi = {10.1021/acs.jpca.9b03326},
 journal = {Journal of Physical Chemistry A},
 number = {26}
}

The size-resolved composition of nanoparticles formed and grown through acid-base reactive uptake has been studied in the laboratory by reacting gas-phase nitric acid (HNO3) and dimethylamine (DMA) in a flow tube under dry (<5% RH) and humid (∼55% RH) conditions. Size-resolved nanoparticle composition was measured by a thermal desorption chemical ionization mass spectrometer over the diameter range of 9-30 nm. The nanoparticle geometric mean diameter grew in the presence of water compared to dry conditions. Acid/base ratios of HNO3-DMA particles at all measured sizes did not strongly deviate from neutral (1:1) in either RH condition, which contrasts with prior laboratory studies of nanoparticles made from sulfuric acid (H2SO4) and base. Theoretical methods were used to investigate the underlying chemical processes that explain observed differences in the compositions of HNO3-DMA and H2SO4-DMA particles. Calculations of HNO3-DMA cluster stability indicated that a 1:1 acid/base ratio has >107 smaller evaporation rates than any other acid/base ratio in this system, and measured nanoparticle composition confirm this to be the most stable pathway for growth up to 30 nm particles. This study demonstrates that nanoparticle formation and growth via acid-base reactive uptake of HNO3 and DMA follow the thermodynamic theory, likely because of both components' volatility.

@article{
 title = {Chemical characterization of nanoparticles and volatiles present in mainstream hookah smoke},
 type = {article},
 year = {2019},
 pages = {1023-1039},
 volume = {53},
 id = {4612439a-b783-30ec-8d8a-7150e3323778},
 created = {2019-07-11T17:26:48.348Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-08-21T23:00:50.627Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Perraud2019},
 private_publication = {false},
 abstract = {Waterpipe smoking is becoming more popular worldwide and there is a pressing need to better characterize the exposure of smokers to chemical compounds present in the mainstream smoke. We report real-time measurements of mainstream smoke for carbon monoxide, volatile organic compounds and nanoparticle size distribution and chemical composition using a custom dilution flow tube. A conventional tobacco mixture, a dark leaf unwashed tobacco, and a nicotine-free herbal tobacco were studied. Results show that carbon monoxide is present in the mainstream smoke and originates primarily from the charcoal used to heat the tobacco. Online measurements of volatile organic compounds in mainstream smoke showed an overwhelming contribution from glycerol and its decomposition products. Gas phase analysis also showed that very little filtration of the gas phase products is provided by the percolation of mainstream smoke through water. Waterpipe smoking generated high concentrations of 4–100 nm nanoparticles, which were mainly composed of sugar derivatives and especially abundant in the first 10 min of the smoking session. These measured emissions of volatiles and particles are compared with those from a reference cigarette (3R4F) and represent the equivalent of the emission of one or more entire cigarettes for a single puff of hookah smoke. Considerations related to the health impacts of waterpipe smoking are discussed.},
 bibtype = {article},
 author = {Perraud, Véronique and Lawler, Michael J. and Malecha, Kurtis T. and Johnson, Rebecca M. and Herman, David A. and Staimer, Norbert and Kleinman, Michael T. and Nizkorodov, Sergey A. and Smith, James N.},
 doi = {10.1080/02786826.2019.1628342},
 journal = {Aerosol Science and Technology},
 number = {9}
}

Waterpipe smoking is becoming more popular worldwide and there is a pressing need to better characterize the exposure of smokers to chemical compounds present in the mainstream smoke. We report real-time measurements of mainstream smoke for carbon monoxide, volatile organic compounds and nanoparticle size distribution and chemical composition using a custom dilution flow tube. A conventional tobacco mixture, a dark leaf unwashed tobacco, and a nicotine-free herbal tobacco were studied. Results show that carbon monoxide is present in the mainstream smoke and originates primarily from the charcoal used to heat the tobacco. Online measurements of volatile organic compounds in mainstream smoke showed an overwhelming contribution from glycerol and its decomposition products. Gas phase analysis also showed that very little filtration of the gas phase products is provided by the percolation of mainstream smoke through water. Waterpipe smoking generated high concentrations of 4–100 nm nanoparticles, which were mainly composed of sugar derivatives and especially abundant in the first 10 min of the smoking session. These measured emissions of volatiles and particles are compared with those from a reference cigarette (3R4F) and represent the equivalent of the emission of one or more entire cigarettes for a single puff of hookah smoke. Considerations related to the health impacts of waterpipe smoking are discussed.

@article{
 title = {Chemical composition of ultrafine aerosol particles in central Amazonia during the wet season},
 type = {article},
 year = {2019},
 pages = {13053-13066},
 volume = {19},
 month = {10},
 id = {b0b7f7a6-0935-3ba4-a050-7714ea21e36b},
 created = {2020-02-09T00:05:58.877Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-03-06T15:23:45.683Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {ISI:000492826200001},
 source_type = {article},
 private_publication = {false},
 abstract = {Central Amazonia serves as an ideal location to study atmospheric particle formation, since it often represents nearly natural, pre-industrial conditions but can also experience periods of anthropogenic influence due to the presence of emissions from large metropolitan areas like Manaus, Brazil. Ultrafine (sub-100 nm diameter) particles are often observed in this region, although new particle formation events seldom occur near the ground despite being readily observed in other forested regions with similar emissions of volatile organic compounds (VOCs). This study focuses on identifying the chemical composition of ultrafine particles as a means of determining the chemical species and mechanisms that may be responsible for new particle formation and growth in the region. These measurements were performed during the wet season as part of the Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) field campaign at a site located 70 km southwest of Manaus. A thermal desorption chemical ionization mass spectrometer (TDCIMS) characterized the most abundant compounds detected in ultrafine particles. Two time periods representing distinct influences on aerosol composition, which we label as "anthropogenic" and "background" periods, were studied as part of a larger 10 d period of analysis. Higher particle number concentrations were measured during the anthropogenic period, and modeled back-trajectory frequencies indicate transport of emissions from the Manaus metropolitan area. During the background period there were much lower number concentrations, and back-trajectory frequencies showed that air masses arrived at the site predominantly from the forested regions to the north and northeast. TDCIMS-measured constituents also show distinct differences between the two observational periods. Although bisulfate was detected in particles throughout the 10 d period, the anthropogenic period had higher levels of particulate bisulfate overall. Ammonium and trimethyl ammonium were positively correlated with bisulfate. The background period had distinct diurnal patterns of particulate cyanate and acetate, while oxalate remained relatively constant during the 10 d period. 3-Methylfuran, a thermal decomposition product of a particulate-phase isoprene epoxydiol (IEPOX), was the dominant species measured in the positive-ion mode. Principal component analysis (PCA) was performed on the TDCIMS-measured ion abundance and aerosol mass spectrometer (AMS) mass concentration data. Two different hierarchical clusters representing unique influences arise: one comprising ultrafine particulate acetate, hydrogen oxalate, cyanate, trimethyl ammonium and 3-methylfuran and another made up of ultrafine particulate bisulfate, chloride, ammonium and potassium. A third cluster separated AMS-measured species from the two TDCIMS-derived clusters, indicating different sources or processes in ultrafine aerosol particle formation compared to larger submicron-sized particles.},
 bibtype = {article},
 author = {Glicker, Hayley S. and Lawler, Michael J. and Ortega, John and De Sá, Suzane S. and Martin, Scot T. and Artaxo, Paulo and Vega Bustillos, Oscar and De Souza, Rodrigo and Tota, Julio and Carlton, Annmarie and Smith, James N.},
 doi = {10.5194/acp-19-13053-2019},
 journal = {Atmospheric Chemistry and Physics},
 number = {20}
}

Central Amazonia serves as an ideal location to study atmospheric particle formation, since it often represents nearly natural, pre-industrial conditions but can also experience periods of anthropogenic influence due to the presence of emissions from large metropolitan areas like Manaus, Brazil. Ultrafine (sub-100 nm diameter) particles are often observed in this region, although new particle formation events seldom occur near the ground despite being readily observed in other forested regions with similar emissions of volatile organic compounds (VOCs). This study focuses on identifying the chemical composition of ultrafine particles as a means of determining the chemical species and mechanisms that may be responsible for new particle formation and growth in the region. These measurements were performed during the wet season as part of the Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) field campaign at a site located 70 km southwest of Manaus. A thermal desorption chemical ionization mass spectrometer (TDCIMS) characterized the most abundant compounds detected in ultrafine particles. Two time periods representing distinct influences on aerosol composition, which we label as "anthropogenic" and "background" periods, were studied as part of a larger 10 d period of analysis. Higher particle number concentrations were measured during the anthropogenic period, and modeled back-trajectory frequencies indicate transport of emissions from the Manaus metropolitan area. During the background period there were much lower number concentrations, and back-trajectory frequencies showed that air masses arrived at the site predominantly from the forested regions to the north and northeast. TDCIMS-measured constituents also show distinct differences between the two observational periods. Although bisulfate was detected in particles throughout the 10 d period, the anthropogenic period had higher levels of particulate bisulfate overall. Ammonium and trimethyl ammonium were positively correlated with bisulfate. The background period had distinct diurnal patterns of particulate cyanate and acetate, while oxalate remained relatively constant during the 10 d period. 3-Methylfuran, a thermal decomposition product of a particulate-phase isoprene epoxydiol (IEPOX), was the dominant species measured in the positive-ion mode. Principal component analysis (PCA) was performed on the TDCIMS-measured ion abundance and aerosol mass spectrometer (AMS) mass concentration data. Two different hierarchical clusters representing unique influences arise: one comprising ultrafine particulate acetate, hydrogen oxalate, cyanate, trimethyl ammonium and 3-methylfuran and another made up of ultrafine particulate bisulfate, chloride, ammonium and potassium. A third cluster separated AMS-measured species from the two TDCIMS-derived clusters, indicating different sources or processes in ultrafine aerosol particle formation compared to larger submicron-sized particles.

@article{
 title = {Enhancing Potential of Trimethylamine Oxide on Atmospheric Particle Formation},
 type = {article},
 year = {2019},
 keywords = {Intermolecular interactions,Particle formation,Sulfuric acid,Trimethylamine oxide},
 pages = {35},
 volume = {11},
 websites = {https://doi.org/10.3390%2Fatmos11010035},
 month = {12},
 publisher = {MDPI AG},
 id = {4118cfe8-eae0-3f0d-9116-bbeaf751ec67},
 created = {2023-01-31T22:46:05.903Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:05.903Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Myllys_2019},
 source_type = {article},
 private_publication = {false},
 abstract = {The role of an oxidation product of trimethylamine, trimethylamine oxide, in atmospheric particle formation is studied using quantum chemical methods and cluster formation simulations. Molecular-level cluster formation mechanisms are resolved, and theoretical results on particle formation are confirmed with mass spectrometer measurements. Trimethylamine oxide is capable of forming only one hydrogen bond with sulfuric acid, but unlike amines, trimethylamine oxide can form stable clusters via ion-dipole interactions. That is because of its zwitterionic structure, which causes a high dipole moment. Cluster growth occurs close to the acid:base ratio of 1:1, which is the same as for other monoprotic bases. Enhancement potential of trimethylamine oxide in particle formation is much higher than that of dimethylamine, but lower compared to guanidine. Therefore, at relatively low concentrations and high temperatures, guanidine and trimethylamine oxide may dominate particle formation events over amines.},
 bibtype = {article},
 author = {Myllys, Nanna and Ponkkonen, Tuomo and Chee, Sabrina and Smith, James},
 doi = {10.3390/atmos11010035},
 journal = {Atmosphere},
 number = {1}
}

The role of an oxidation product of trimethylamine, trimethylamine oxide, in atmospheric particle formation is studied using quantum chemical methods and cluster formation simulations. Molecular-level cluster formation mechanisms are resolved, and theoretical results on particle formation are confirmed with mass spectrometer measurements. Trimethylamine oxide is capable of forming only one hydrogen bond with sulfuric acid, but unlike amines, trimethylamine oxide can form stable clusters via ion-dipole interactions. That is because of its zwitterionic structure, which causes a high dipole moment. Cluster growth occurs close to the acid:base ratio of 1:1, which is the same as for other monoprotic bases. Enhancement potential of trimethylamine oxide in particle formation is much higher than that of dimethylamine, but lower compared to guanidine. Therefore, at relatively low concentrations and high temperatures, guanidine and trimethylamine oxide may dominate particle formation events over amines.

@article{
 title = {Relative humidity effect on the formation of highly oxidized molecules and new particles during monoterpene oxidation},
 type = {article},
 year = {2019},
 pages = {1555-1570},
 volume = {19},
 websites = {https://www.atmos-chem-phys.net/19/1555/2019/,https://www.atmos-chem-phys.net/19/1555/2019/acp-19-1555-2019.pdf},
 month = {2},
 publisher = {Copernicus Publications},
 day = {6},
 id = {ec7676ca-6890-3e27-9e37-0f802972f88b},
 created = {2023-01-31T22:46:08.502Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:08.502Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Li2019},
 source_type = {JOUR},
 private_publication = {false},
 abstract = {It has been widely observed around the world that the frequency and intensity of new particle formation (NPF) events are reduced during periods of high relative humidity (RH). The current study focuses on how RH affects the formation of highly oxidized molecules (HOMs), which are key components of NPF and initial growth caused by oxidized organics. The ozonolysis of a-pinene, limonene, and 13- carene, with and without OH scavengers, were carried out under low NOx conditions under a range of RH (from ∼ 3 % to ∼ 92 %) in a temperature-controlled flow tube to generate secondary organic aerosol (SOA). A Scanning Mobility Particle Sizer (SMPS) was used to measure the size distribution of generated particles, and a novel transverse ionization chemical ionization inlet with a high-resolution time-of-fight mass spectrometer detected HOMs. A major finding from this work is that neither the detected HOMs nor their abundance changed significantly with RH, which indicates that the detected HOMs must be formed from water-independent pathways. In fact, the distinguished OH- and O 3 -derived peroxy radicals (RO 2 ), HOM monomers, and HOM dimers could mostly be explained by the autoxidation of RO 2 followed by bimolecular reactions with other RO 2 or hydroperoxy radicals (HO 2 ), rather than from a water-influenced pathway like through the formation of a stabilized Criegee intermediate (sCI). However, as RH increased from ∼ 3 % to ∼ 92 %, the total SOA number concentrations decreased by a factor of 23 while SOA mass concentrations remained relatively constant. These observations show that, while high RH appears to inhibit NPF as evident by the decreasing number concentration, this reduction is not caused by a decrease in RO 2 -derived HOM formation. Possible explanations for these phenomena were discussed.},
 bibtype = {article},
 author = {Li, Xiaoxiao and Chee, Sabrina and Hao, Jiming and Abbatt, Jonathan P.D. D and Jiang, Jingkun and Smith, James N.},
 doi = {10.5194/acp-19-1555-2019},
 journal = {Atmospheric Chemistry and Physics},
 number = {3}
}

It has been widely observed around the world that the frequency and intensity of new particle formation (NPF) events are reduced during periods of high relative humidity (RH). The current study focuses on how RH affects the formation of highly oxidized molecules (HOMs), which are key components of NPF and initial growth caused by oxidized organics. The ozonolysis of a-pinene, limonene, and 13- carene, with and without OH scavengers, were carried out under low NOx conditions under a range of RH (from ∼ 3 % to ∼ 92 %) in a temperature-controlled flow tube to generate secondary organic aerosol (SOA). A Scanning Mobility Particle Sizer (SMPS) was used to measure the size distribution of generated particles, and a novel transverse ionization chemical ionization inlet with a high-resolution time-of-fight mass spectrometer detected HOMs. A major finding from this work is that neither the detected HOMs nor their abundance changed significantly with RH, which indicates that the detected HOMs must be formed from water-independent pathways. In fact, the distinguished OH- and O 3 -derived peroxy radicals (RO 2 ), HOM monomers, and HOM dimers could mostly be explained by the autoxidation of RO 2 followed by bimolecular reactions with other RO 2 or hydroperoxy radicals (HO 2 ), rather than from a water-influenced pathway like through the formation of a stabilized Criegee intermediate (sCI). However, as RH increased from ∼ 3 % to ∼ 92 %, the total SOA number concentrations decreased by a factor of 23 while SOA mass concentrations remained relatively constant. These observations show that, while high RH appears to inhibit NPF as evident by the decreasing number concentration, this reduction is not caused by a decrease in RO 2 -derived HOM formation. Possible explanations for these phenomena were discussed.

@article{
 title = {Molecular-Level Understanding of Synergistic Effects in Sulfuric Acid\textendashAmine\textendashAmmonia Mixed Clusters},
 type = {article},
 year = {2019},
 pages = {2420-2425},
 volume = {123},
 websites = {https://doi.org/10.1021%2Facs.jpca.9b00909},
 month = {3},
 publisher = {American Chemical Society (ACS)},
 id = {40d31f78-e416-3597-893a-c47d1a12d33e},
 created = {2023-01-31T22:46:13.260Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:13.260Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Myllys_2019},
 source_type = {article},
 private_publication = {false},
 bibtype = {article},
 author = {Myllys, Nanna and Chee, Sabrina and Olenius, Tinja and Lawler, Michael and Smith, James},
 doi = {10.1021/acs.jpca.9b00909},
 journal = {The Journal of Physical Chemistry A},
 number = {12}
}

@article{
 title = {Resolving nanoparticle growth mechanisms from size- and time-dependent growth rate analysis},
 type = {article},
 year = {2018},
 pages = {1307-1323},
 volume = {18},
 month = {1},
 id = {1efd7b5e-9725-3f06-8c18-230add5f880b},
 created = {2018-07-30T00:10:58.577Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-08-21T23:00:46.529Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {ISI:000423701200005},
 source_type = {article},
 folder_uuids = {e9db4589-c14d-471c-8b7a-bb4b8e16be27},
 private_publication = {false},
 abstract = {Atmospheric new particle formation occurs frequently in the global atmosphere and may play a crucial role in climate by affecting cloud properties. The relevance of newly formed nanoparticles depends largely on the dynamics governing their initial formation and growth to sizes where they become important for cloud microphysics. One key to the proper understanding of nanoparticle effects on climate is therefore hidden in the growth mechanisms. In this study we have developed and successfully tested two independent methods based on the aerosol general dynamics equation, allowing detailed retrieval of time- and size-dependent nanoparticle growth rates. Both methods were used to analyze particle formation from two different biogenic precursor vapors in controlled chamber experiments. Our results suggest that growth rates below 10 nm show much more variation than is currently thought and pin down the decisive size range of growth at around 5 nm where in-depth studies of physical and chemical particle properties are needed.},
 bibtype = {article},
 author = {Pichelstorfer, Lukas and Stolzenburg, Dominik and Ortega, John and Karl, Thomas and Kokkola, Harri and Laakso, Anton and Lehtinen, Kari E.J. and Smith, James N. and McMurry, Peter H. and Winkler, Paul M.},
 doi = {10.5194/acp-18-1307-2018},
 journal = {Atmospheric Chemistry and Physics},
 number = {2}
}

Atmospheric new particle formation occurs frequently in the global atmosphere and may play a crucial role in climate by affecting cloud properties. The relevance of newly formed nanoparticles depends largely on the dynamics governing their initial formation and growth to sizes where they become important for cloud microphysics. One key to the proper understanding of nanoparticle effects on climate is therefore hidden in the growth mechanisms. In this study we have developed and successfully tested two independent methods based on the aerosol general dynamics equation, allowing detailed retrieval of time- and size-dependent nanoparticle growth rates. Both methods were used to analyze particle formation from two different biogenic precursor vapors in controlled chamber experiments. Our results suggest that growth rates below 10 nm show much more variation than is currently thought and pin down the decisive size range of growth at around 5 nm where in-depth studies of physical and chemical particle properties are needed.

@article{
 title = {Rapid growth of organic aerosol nanoparticles over a wide tropospheric temperature range},
 type = {article},
 year = {2018},
 keywords = {Aerosol formation,Aerosols,CLOUD experiment,Nanoparticle growth,Volatile organic compounds},
 pages = {9122-9127},
 volume = {115},
 id = {f1139500-925b-3d99-90b1-03ef00a5a634},
 created = {2018-11-21T20:51:12.085Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-08-21T23:00:48.333Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Stolzenburg2018},
 source_type = {JOUR},
 private_publication = {false},
 abstract = {Nucleation and growth of aerosol particles from atmospheric vapors constitutes a major source of global cloud condensation nuclei (CCN). The fraction of newly formed particles that reaches CCN sizes is highly sensitive to particle growth rates, especially for particle sizes <10 nm, where coagulation losses to larger aerosol particles are greatest. Recent results show that some oxidation products from biogenic volatile organic compounds are major contributors to particle formation and initial growth. However, whether oxidized organics contribute to particle growth over the broad span of tropospheric temperatures remains an open question, and quantitative mass balance for organic growth has yet to be demonstrated at any temperature. Here, in experiments performed under atmospheric conditions in the Cosmics Leaving Outdoor Droplets (CLOUD) chamber at the European Organization for Nuclear Research (CERN), we show that rapid growth of organic particles occurs over the range from −25 ◦C to 25 ◦C. The lower extent of autoxidation at reduced temperatures is compensated by the decreased volatility of all oxidized molecules. This is confirmed by particle-phase composition measurements, showing enhanced uptake of relatively less oxygenated products at cold temperatures. We can reproduce the measured growth rates using an aerosol growth model based entirely on the experimentally measured gas-phase spectra of oxidized organic molecules obtained from two complementary mass spectrometers. We show that the growth rates are sensitive to particle curvature, explaining widespread atmospheric observations that particle growth rates increase in the single-digit-nanometer size range. Our results demonstrate that organic vapors can contribute to particle growth over a wide range of tropospheric temperatures from molecular cluster sizes onward.},
 bibtype = {article},
 author = {Stolzenburg, Dominik and Fischer, Lukas and Vogel, Alexander L. and Heinritzi, Martin and Schervish, Meredith and Simon, Mario and Wagner, Andrea C. and Dada, Lubna and Ahonen, Lauri R. and Amorim, Antonio and Baccarini, Andrea and Bauer, Paulus S. and Baumgartner, Bernhard and Bergen, Anton and Bianchi, Federico and Breitenlechner, Martin and Brilke, Sophia and Mazon, Stephany Buenrostro and Chen, Dexian and Dias, António and Draper, Danielle C. and Duplissy, Jonathan and Haddad, Imad El and Finkenzeller, Henning and Frege, Carla and Fuchs, Claudia and Garmash, Olga and Gordon, Hamish and He, Xucheng and Helm, Johanna and Hofbauer, Victoria and Hoyle, Christopher R. and Kim, Changhyuk and Kirkby, Jasper and Kontkanen, Jenni and Kürten, Andreas and Lampilahti, Janne and Lawler, Michael and Lehtipalo, Katrianne and Leiminger, Markus and Mai, Huajun and Mathot, Serge and Mentler, Bernhard and Molteni, Ugo and Nie, Wei and Nieminen, Tuomo and Nowak, John B. and Ojdanic, Andrea and Onnela, Antti and Passananti, Monica and Petäjä, Tuukka and Quéléver, Lauriane L.J. and Rissanen, Matti P. and Sarnela, Nina and Schallhart, Simon and Tauber, Christian and Tomé, António and Wagner, Robert and Wang, Mingyi and Weitz, Lena and Wimmer, Daniela and Xiao, Mao and Yan, Chao and Ye, Penglin and Zha, Qiaozhi and Baltensperger, Urs and Curtius, Joachim and Dommen, Josef and Flagan, Richard C. and Kulmala, Markku and Smith, James N. and Worsnop, Douglas R. and Hansel, Armin and Donahue, Neil M. and Winkler, Paul M.},
 doi = {10.1073/pnas.1807604115},
 journal = {Proceedings of the National Academy of Sciences of the United States of America},
 number = {37}
}

Nucleation and growth of aerosol particles from atmospheric vapors constitutes a major source of global cloud condensation nuclei (CCN). The fraction of newly formed particles that reaches CCN sizes is highly sensitive to particle growth rates, especially for particle sizes <10 nm, where coagulation losses to larger aerosol particles are greatest. Recent results show that some oxidation products from biogenic volatile organic compounds are major contributors to particle formation and initial growth. However, whether oxidized organics contribute to particle growth over the broad span of tropospheric temperatures remains an open question, and quantitative mass balance for organic growth has yet to be demonstrated at any temperature. Here, in experiments performed under atmospheric conditions in the Cosmics Leaving Outdoor Droplets (CLOUD) chamber at the European Organization for Nuclear Research (CERN), we show that rapid growth of organic particles occurs over the range from −25 ◦C to 25 ◦C. The lower extent of autoxidation at reduced temperatures is compensated by the decreased volatility of all oxidized molecules. This is confirmed by particle-phase composition measurements, showing enhanced uptake of relatively less oxygenated products at cold temperatures. We can reproduce the measured growth rates using an aerosol growth model based entirely on the experimentally measured gas-phase spectra of oxidized organic molecules obtained from two complementary mass spectrometers. We show that the growth rates are sensitive to particle curvature, explaining widespread atmospheric observations that particle growth rates increase in the single-digit-nanometer size range. Our results demonstrate that organic vapors can contribute to particle growth over a wide range of tropospheric temperatures from molecular cluster sizes onward.

@article{
 title = {Constraining nucleation, condensation, and chemistry in oxidation flow reactors using size-distribution measurements and aerosol microphysical modeling},
 type = {article},
 year = {2018},
 pages = {12433-12460},
 volume = {18},
 id = {55c0c447-a2ae-3415-8d03-eae6affee3d4},
 created = {2018-11-21T20:51:12.195Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-08-21T23:00:48.202Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Hodshire2018},
 source_type = {JOUR},
 private_publication = {false},
 abstract = {Oxidation flow reactors (OFRs) allow the concentration of a given atmospheric oxidant to be increased beyond ambient levels in order to study secondary organic aerosol (SOA) formation and aging over varying periods of equivalent aging by that oxidant. Previous studies have used these reactors to determine the bulk OA mass and chemical evolution. To our knowledge, no OFR study has focused on the interpretation of the evolving aerosol size distributions. In this study, we use size-distribution measurements of the OFR and an aerosol microphysics model to learn about size-dependent processes in the OFR. Specifically, we use OFR exposures between 0.09 and 0.9 equivalent days of OH aging from the 2011 BEACHON-RoMBAS and GoAmazon2014/5 field campaigns. We use simulations in the TOMAS (TwO-Moment Aerosol Sectional) microphysics box model to constrain the following parameters in the OFR: (1) the rate constant of gas-phase functionalization reactions of organic compounds with OH, (2) the rate constant of gas-phase fragmentation reactions of organic compounds with OH, (3) the reactive uptake coefficient for heterogeneous fragmentation reactions with OH, (4) the nucleation rate constants for three different nucleation schemes, and (5) an effective accommodation coefficient that accounts for possible particle diffusion limitations of particles larger than 60nm in diameter. We find the best model-to-measurement agreement when the accommodation coefficient of the larger particles (Dp>60nm) was 0.1 or lower (with an accommodation coefficient of 1 for smaller particles), which suggests a diffusion limitation in the larger particles. When using these low accommodation-coefficient values, the model agrees with measurements when using a published H2SO4-organics nucleation mechanism and previously published values of rate constants for gas-phase oxidation reactions. Further, gas-phase fragmentation was found to have a significant impact upon the size distribution, and including fragmentation was necessary for accurately simulating the distributions in the OFR. The model was insensitive to the value of the reactive uptake coefficient on these aging timescales. Monoterpenes and isoprene could explain 24%-95% of the observed change in total volume of aerosol in the OFR, with ambient semivolatile and intermediate-volatility organic compounds (S/IVOCs) appearing to explain the remainder of the change in total volume. These results provide support to the mass-based findings of previous OFR studies, give insight to important size-distribution dynamics in the OFR, and enable the design of future OFR studies focused on new particle formation and/or microphysical processes.},
 bibtype = {article},
 author = {Hodshire, Anna L. and Palm, Brett B. and Alexander, M. Lizabeth and Bian, Qijing and Campuzano-Jost, Pedro and Cross, Eben S. and Day, Douglas A. and De Sá, Suzane S. and Guenther, Alex B. and Hansel, Armin and Hunter, James F. and Jud, Werner and Karl, Thomas and Kim, Saewung and Kroll, Jesse H. and Park, Jeong Hoo and Peng, Zhe and Seco, Roger and Smith, James N. and Jimenez, Jose L. and Pierce, Jeffrey R.},
 doi = {10.5194/acp-18-12433-2018},
 journal = {Atmospheric Chemistry and Physics},
 number = {16}
}

Oxidation flow reactors (OFRs) allow the concentration of a given atmospheric oxidant to be increased beyond ambient levels in order to study secondary organic aerosol (SOA) formation and aging over varying periods of equivalent aging by that oxidant. Previous studies have used these reactors to determine the bulk OA mass and chemical evolution. To our knowledge, no OFR study has focused on the interpretation of the evolving aerosol size distributions. In this study, we use size-distribution measurements of the OFR and an aerosol microphysics model to learn about size-dependent processes in the OFR. Specifically, we use OFR exposures between 0.09 and 0.9 equivalent days of OH aging from the 2011 BEACHON-RoMBAS and GoAmazon2014/5 field campaigns. We use simulations in the TOMAS (TwO-Moment Aerosol Sectional) microphysics box model to constrain the following parameters in the OFR: (1) the rate constant of gas-phase functionalization reactions of organic compounds with OH, (2) the rate constant of gas-phase fragmentation reactions of organic compounds with OH, (3) the reactive uptake coefficient for heterogeneous fragmentation reactions with OH, (4) the nucleation rate constants for three different nucleation schemes, and (5) an effective accommodation coefficient that accounts for possible particle diffusion limitations of particles larger than 60nm in diameter. We find the best model-to-measurement agreement when the accommodation coefficient of the larger particles (Dp>60nm) was 0.1 or lower (with an accommodation coefficient of 1 for smaller particles), which suggests a diffusion limitation in the larger particles. When using these low accommodation-coefficient values, the model agrees with measurements when using a published H2SO4-organics nucleation mechanism and previously published values of rate constants for gas-phase oxidation reactions. Further, gas-phase fragmentation was found to have a significant impact upon the size distribution, and including fragmentation was necessary for accurately simulating the distributions in the OFR. The model was insensitive to the value of the reactive uptake coefficient on these aging timescales. Monoterpenes and isoprene could explain 24%-95% of the observed change in total volume of aerosol in the OFR, with ambient semivolatile and intermediate-volatility organic compounds (S/IVOCs) appearing to explain the remainder of the change in total volume. These results provide support to the mass-based findings of previous OFR studies, give insight to important size-distribution dynamics in the OFR, and enable the design of future OFR studies focused on new particle formation and/or microphysical processes.

@article{
 title = {Tropospheric HONO distribution and chemistry in the southeastern US},
 type = {article},
 year = {2018},
 pages = {9107-9120},
 volume = {18},
 id = {904130bf-8d2c-3216-af6f-b7018879fc85},
 created = {2018-11-21T20:51:12.360Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-08-21T23:00:48.214Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Ye2018},
 source_type = {JOUR},
 private_publication = {false},
 abstract = {Here we report the measurement results of nitrous acid (HONO) and a suite of relevant parameters on the NCAR C-130 research aircraft in the southeastern US during the NOMADSS 2013 summer field study. The daytime HONO concentration ranged from low parts per trillion by volume (pptv) in the free troposphere (FT) to mostly within 5-15 pptv in the background planetary boundary layer (PBL). There was no discernible vertical HONO gradient above the lower flight altitude of 300 m in the PBL, and the transport of ground surface HONO was not found to be a significant contributor to the tropospheric HONO budget. The total in situ HONO source mean (±1 SD) was calculated as 53 (±21) pptv h-1 during the day. The upper-limit contribution from NO-related reactions was 10 (±5) pptv h-1, and the contribution from photolysis of particulate nitrate (pNO3) was 38 (±23) pptv h-1, based on the measured pNO3 concentrations and the median pNO3 photolysis rate constant of 2.0 × 10-4 s-1 determined in the laboratory using ambient aerosol samples. The photolysis of HONO contributed to less than 10 % of the primary OH source. However, a recycling NOx source via pNO3 photolysis was equivalent to ~ 2.3 × 10-6 mol m-2 h-1 in the air column within the PBL, a considerable supplementary NOx source in the low-NOx background area. Up to several tens of parts per trillion by volume of HONO were observed in power plant and urban plumes during the day, mostly produced in situ from precursors including NOx and pNO3. Finally, there was no observable accumulation of HONO in the nocturnal residual layer and the nocturnal FT in the background southeastern US, with an increase in the HONO / NOx ratio of ≤ 3 × 10-4 h-1 after sunset.},
 bibtype = {article},
 author = {Ye, Chunxiang and Zhou, Xianliang and Pu, Dennis and Stutz, Jochen and Festa, James and Spolaor, Max and Tsai, Catalina and Cantrell, Christopher and Mauldin, Roy L. and Weinheimer, Andrew and Hornbrook, Rebecca S. and Apel, Eric C. and Guenther, Alex and Kaser, Lisa and Yuan, Bin and Karl, Thomas and Haggerty, Julie and Hall, Samuel and Ullmann, Kirk and Smith, James and Ortega, John},
 doi = {10.5194/acp-18-9107-2018},
 journal = {Atmospheric Chemistry and Physics},
 number = {12}
}

Here we report the measurement results of nitrous acid (HONO) and a suite of relevant parameters on the NCAR C-130 research aircraft in the southeastern US during the NOMADSS 2013 summer field study. The daytime HONO concentration ranged from low parts per trillion by volume (pptv) in the free troposphere (FT) to mostly within 5-15 pptv in the background planetary boundary layer (PBL). There was no discernible vertical HONO gradient above the lower flight altitude of 300 m in the PBL, and the transport of ground surface HONO was not found to be a significant contributor to the tropospheric HONO budget. The total in situ HONO source mean (±1 SD) was calculated as 53 (±21) pptv h-1 during the day. The upper-limit contribution from NO-related reactions was 10 (±5) pptv h-1, and the contribution from photolysis of particulate nitrate (pNO3) was 38 (±23) pptv h-1, based on the measured pNO3 concentrations and the median pNO3 photolysis rate constant of 2.0 × 10-4 s-1 determined in the laboratory using ambient aerosol samples. The photolysis of HONO contributed to less than 10 % of the primary OH source. However, a recycling NOx source via pNO3 photolysis was equivalent to ~ 2.3 × 10-6 mol m-2 h-1 in the air column within the PBL, a considerable supplementary NOx source in the low-NOx background area. Up to several tens of parts per trillion by volume of HONO were observed in power plant and urban plumes during the day, mostly produced in situ from precursors including NOx and pNO3. Finally, there was no observable accumulation of HONO in the nocturnal residual layer and the nocturnal FT in the background southeastern US, with an increase in the HONO / NOx ratio of ≤ 3 × 10-4 h-1 after sunset.

@article{
 title = {Evidence for Diverse Biogeochemical Drivers of Boreal Forest New Particle Formation},
 type = {article},
 year = {2018},
 keywords = {aerosol,atmospheric chemistry,boreal forest,marine,new particle formation,nucleation},
 pages = {2038-2046},
 volume = {45},
 month = {2},
 publisher = {AMER GEOPHYSICAL UNION},
 city = {2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA},
 id = {daaba17f-dde4-31b2-8df8-bda7c78ddf34},
 created = {2019-12-30T23:08:28.071Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2021-12-15T15:07:25.430Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {ISI:000427564300040},
 source_type = {article},
 user_context = {Article},
 folder_uuids = {e9db4589-c14d-471c-8b7a-bb4b8e16be27},
 private_publication = {false},
 abstract = {New particle formation (NPF) is an important contributor to particle number in many locations, but the chemical drivers for this process are not well understood. Daytime NPF events occur regularly in the springtime Finnish boreal forest and strongly impact aerosol abundance. In April 2014 size-resolved chemical measurements of ambient nanoparticles were made using the Time-of-Flight Thermal Desorption Chemical ionization Mass Spectrometer and we report results from two NPF events. While growth overall was dominated by terpene oxidation products, newly formed 20–70 nm particles showed enhancement in apparent alkanoic acids. The events occurred on days with rapid transport of marine air, which correlated with low background aerosol loading and higher gas phase methanesulfonic acid levels. These results are broadly consistent with previous studies on Nordic NPF but indicate that further attention should be given to the sources and role of non-terpenoid organics and the possible contribution of transported marine compounds in this process.},
 bibtype = {article},
 author = {Lawler, Michael J. and Rissanen, Matti P. and Ehn, Mikael and Mauldin, R. Lee and Sarnela, Nina and Sipilä, Mikko and Smith, James N.},
 doi = {10.1002/2017GL076394},
 journal = {Geophysical Research Letters},
 number = {4}
}

New particle formation (NPF) is an important contributor to particle number in many locations, but the chemical drivers for this process are not well understood. Daytime NPF events occur regularly in the springtime Finnish boreal forest and strongly impact aerosol abundance. In April 2014 size-resolved chemical measurements of ambient nanoparticles were made using the Time-of-Flight Thermal Desorption Chemical ionization Mass Spectrometer and we report results from two NPF events. While growth overall was dominated by terpene oxidation products, newly formed 20–70 nm particles showed enhancement in apparent alkanoic acids. The events occurred on days with rapid transport of marine air, which correlated with low background aerosol loading and higher gas phase methanesulfonic acid levels. These results are broadly consistent with previous studies on Nordic NPF but indicate that further attention should be given to the sources and role of non-terpenoid organics and the possible contribution of transported marine compounds in this process.

@article{
 title = {Vertically resolved concentration and liquid water content of atmospheric nanoparticles at the US DOE Southern Great Plains site},
 type = {article},
 year = {2018},
 pages = {311-326},
 volume = {18},
 websites = {https://www.atmos-chem-phys-discuss.net/acp-2017-586/},
 id = {3436b7ce-6da7-338c-866c-ab9bb175946f},
 created = {2023-01-31T22:46:08.166Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:08.166Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Chen2018},
 source_type = {JOUR},
 notes = {<b>From Duplicate 1 (<i>Vertically resolved concentration and liquid water content of atmospheric nanoparticles at the US DOE Southern Great Plains site</i> - Chen, Haihan; Hodshire, Anna L.; Ortega, John; Greenberg, James; McMurry, Peter H.; Carlton, Annmarie G.; Pierce, Jeffrey R.; Hanson, Dave R.; Smith, James N.)<br/></b><br/>ACPD},
 private_publication = {false},
 abstract = {Most prior field studies of new particle formation (NPF) have been performed at or near ground level, leaving many unanswered questions regarding the vertical extent of NPF. To address this, we measured concentrations of 11-16 nm diameter particles from ground level to 1000m during the 2013 New Particle Formation Study at the Atmospheric Radiation Measurement Southern Great Plains site in Lamont, Oklahoma. The measurements were performed using a tethered balloon carrying two condensation particle counters that were configured for two different particle cut-off diameters. These observations were compared to data from three scanning mobility particle sizers at the ground level. We observed that 11-16 nm diameter particles were generated at the top region of the boundary layer, and were then rapidly mixed throughout the boundary layer. We also estimate liquid water content of nanoparticles using ground-based measurements of particle hygroscopicity obtained with a Humidified Tandem Differential Mobility Analyzer and vertically resolved relative humidity (RH) and temperature measured with a Raman lidar. Our analyses of these observations lead to the following conclusions regarding nanoparticles formed during NPF events at this site: (1) ground-based observations may not always accurately represent the timing, distribution, and meteorological conditions associated with the onset of NPF; (2) nanoparticles are highly hygroscopic and typically contain up to 50% water by volume, and during conditions of high RH combined with high particle hygroscopicity, particles can be up to 95%water by volume; (3) increased liquid water content of nanoparticles at high RH greatly enhances the partitioning of water-soluble species like organic acids into ambient nanoparticles.},
 bibtype = {article},
 author = {Chen, Haihan and Hodshire, A.L. Anna L. and Ortega, John and Greenberg, James and McMurry, P.H. Peter H. and Carlton, A.G. Annmarie G. and Pierce, J.R. Jeffrey R. and Hanson, Dave R. D.R. and Smith, James N. J.N.},
 doi = {10.5194/acp-18-311-2018},
 journal = {Atmospheric Chemistry and Physics},
 number = {1}
}

Most prior field studies of new particle formation (NPF) have been performed at or near ground level, leaving many unanswered questions regarding the vertical extent of NPF. To address this, we measured concentrations of 11-16 nm diameter particles from ground level to 1000m during the 2013 New Particle Formation Study at the Atmospheric Radiation Measurement Southern Great Plains site in Lamont, Oklahoma. The measurements were performed using a tethered balloon carrying two condensation particle counters that were configured for two different particle cut-off diameters. These observations were compared to data from three scanning mobility particle sizers at the ground level. We observed that 11-16 nm diameter particles were generated at the top region of the boundary layer, and were then rapidly mixed throughout the boundary layer. We also estimate liquid water content of nanoparticles using ground-based measurements of particle hygroscopicity obtained with a Humidified Tandem Differential Mobility Analyzer and vertically resolved relative humidity (RH) and temperature measured with a Raman lidar. Our analyses of these observations lead to the following conclusions regarding nanoparticles formed during NPF events at this site: (1) ground-based observations may not always accurately represent the timing, distribution, and meteorological conditions associated with the onset of NPF; (2) nanoparticles are highly hygroscopic and typically contain up to 50% water by volume, and during conditions of high RH combined with high particle hygroscopicity, particles can be up to 95%water by volume; (3) increased liquid water content of nanoparticles at high RH greatly enhances the partitioning of water-soluble species like organic acids into ambient nanoparticles.

@misc{
 title = {Size resolved chemical composition of nanoparticles from reactions of sulfuric acid with ammonia and dimethylamine},
 type = {misc},
 year = {2018},
 source = {Aerosol Science and Technology},
 keywords = {Paul Ziemann},
 pages = {1120-1133},
 volume = {52},
 issue = {10},
 id = {8bf4584c-6fcb-3a18-8e56-2a469568fff1},
 created = {2023-01-31T22:46:14.005Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:14.005Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Chen2018a},
 private_publication = {false},
 abstract = {Nanoparticle formation and growth driven by acid-base chemistry was investigated by introducing gas-phase sulfuric acid (H2SO4) with ammonia (NH3) or dimethylamine (DMA) into a flow tube reactor. A thermal desorption chemical Ionization mass spectrometer was used to measure the size-resolved chemical composition of H2SO4-DMA and H2SO4- NH3 nanoparticles formed under dry conditions and at 60% relative humidity. In contrast with predictions for bulk aqueous systems, nanoparticles showed a strong size-dependent composition gradient and did not always reach a fully neutralized state in excess of gas-phase base. Smaller particles were more acidic, with an acid:base ratio of 0.7 ± 0.1 and 1.3 ± 0.3 for 8.6 and 9.5 nm H2SO4-DMA particles formed under dry and humid conditions, respectively, and 3.1 ± 0.6 and 3.4 ± 0.3 for 7.5 nm H2SO4-NH3 particles formed under dry and humid conditions, respectively. The acidity of particles generally decreased as particles grew. H2SO4-DMA particles became fully neutralized as they grew to 14 nm, but H2SO4-NH3 particles at 12 nm were still acidic and were never observed to reach bulk sample thermodynamic equilibrium for the experimental conditions in this study. Thermodynamic modeling demonstrated that the observed trends can be reproduced by modifying acid dissociation constants to minimize acid-base chemistry, which may be caused by steric or mixing effects, and by considering volatilization of the neutral base. Copyright © 2018 American Association for Aerosol Research.},
 bibtype = {misc},
 author = {Chen, Haihan and Chee, Sabrina and Lawler, Michael J. and Barsanti, Kelley C. and Wong, Bryan M. and Smith, James N.},
 doi = {10.1080/02786826.2018.1490005}
}

Nanoparticle formation and growth driven by acid-base chemistry was investigated by introducing gas-phase sulfuric acid (H2SO4) with ammonia (NH3) or dimethylamine (DMA) into a flow tube reactor. A thermal desorption chemical Ionization mass spectrometer was used to measure the size-resolved chemical composition of H2SO4-DMA and H2SO4- NH3 nanoparticles formed under dry conditions and at 60% relative humidity. In contrast with predictions for bulk aqueous systems, nanoparticles showed a strong size-dependent composition gradient and did not always reach a fully neutralized state in excess of gas-phase base. Smaller particles were more acidic, with an acid:base ratio of 0.7 ± 0.1 and 1.3 ± 0.3 for 8.6 and 9.5 nm H2SO4-DMA particles formed under dry and humid conditions, respectively, and 3.1 ± 0.6 and 3.4 ± 0.3 for 7.5 nm H2SO4-NH3 particles formed under dry and humid conditions, respectively. The acidity of particles generally decreased as particles grew. H2SO4-DMA particles became fully neutralized as they grew to 14 nm, but H2SO4-NH3 particles at 12 nm were still acidic and were never observed to reach bulk sample thermodynamic equilibrium for the experimental conditions in this study. Thermodynamic modeling demonstrated that the observed trends can be reproduced by modifying acid dissociation constants to minimize acid-base chemistry, which may be caused by steric or mixing effects, and by considering volatilization of the neutral base. Copyright © 2018 American Association for Aerosol Research.

@article{
 title = {The green ocean amazon experiment (GOAMAZON2014/5) observes pollution affecting gases, aerosols, clouds, and rainfall over the rain forest},
 type = {article},
 year = {2017},
 pages = {981-997},
 volume = {98},
 websites = {http://journals.ametsoc.org/doi/10.1175/BAMS-D-15-00221.1},
 month = {5},
 id = {2d4765ec-8df7-378a-957e-c479f5c3be22},
 created = {2017-09-20T23:09:09.267Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-08-21T23:09:05.271Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {RID:0920171839923-270},
 source_type = {article},
 private_publication = {false},
 abstract = {The susceptibility of air quality, weather, terrestrial ecosystems, and climate to human activities was investigated in a tropical environment.},
 bibtype = {article},
 author = {Martin, S. T. and Artaxo, P. and Machado, L. and Manzi, A. O. and Souza, R. A.F. and Schumacher, C. and Wang, J. and Biscaro, T. and Brito, J. and Calheiros, A. and Jardine, K. and Medeiros, A. and Portela, B. and De Sá, S. S. and Adachi, K. and Aiken, A. C. and Alblbrecht, R. and Alexander, L. and Andreae, M. O. and Barbosa, H. M.J. and Buseck, P. and Chand, D. and Comstmstmstock, J. M. and Day, D. A. and Dubey, M. and Fan, J. and Fastst, J. and Fisch, G. and Fortner, E. and Giangrande, S. and Gilllles, M. and Goldststein, A. H. and Guenther, A. and Hubbbbe, J. and Jensen, M. and Jimenez, J. L. and Keutstsch, F. N. and Kim, S. and Kuang, C. and Laskskin, A. and McKinney, K. and Mei, F. and Millller, M. and Nascimento, R. and Pauliquevis, T. and Pekour, M. and Peres, J. and Petäjä, T. and Pöhlklker, C. and Pöschl, U. and Rizzo, L. and Schmid, B. and Shilllling, J. E. and Silva Dias, M. A. and Smith, J. N. and Tomlmlinson, J. M. and Tóta, J. and Wendisch, M.},
 doi = {10.1175/BAMS-D-15-00221.1},
 journal = {Bulletin of the American Meteorological Society},
 number = {5}
}

The susceptibility of air quality, weather, terrestrial ecosystems, and climate to human activities was investigated in a tropical environment.

@article{
 title = {Comprehensive characterization of atmospheric organic carbon at a forested site},
 type = {article},
 year = {2017},
 keywords = {ponderosa pine forest volatility basis-set beachon},
 pages = {748-753},
 volume = {10},
 city = {[Hunter, James F.; Carrasquillo, Anthony J.; Heald, Colette L.; Kroll, Jesse H.] MIT, Dept Civil & Environm Engn, Cambridge, MA 02139 USA. [Hunter, James F.; Cross, Eben S.] MIT, Dept Mat Sci & Engn, Cambridge, MA 02139 USA. [Day, Douglas A.; Palm, Brett },
 id = {849945d6-bf30-315d-bdfa-2ab4b5b93d27},
 created = {2018-01-01T21:59:36.068Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
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 citation_key = {Hunter2017},
 source_type = {JOUR},
 language = {English},
 notes = {ISI Document Delivery No.: FI6JV<br/>Times Cited: 0<br/>Cited Reference Count: 48<br/>Hunter, James F. Day, Douglas A. Palm, Brett B. Yatavelli, Reddy L. N. Chan, ArthurW. H. Kaser, Lisa Cappellin, Luca Hayes, Patrick L. Cross, Eben S. Carrasquillo, Anthony J. Campuzano-Jost, Pedro Stark, Harald Zhao, Yunliang Hohaus, Thorsten Smith, James N. Hansel, Armin Karl, Thomas Goldstein, Allen H. Guenther, Alex Worsnop, Douglas R. Thornton, Joel A. Heald, Colette L. Jimenez, Jose L. Kroll, Jesse H.<br/>NOAA [NA10OAR4310106]; NSF [ATM-0919189, AGS-1243354, RAPID 1135745, AGS-1238109]; DOE [DE-SC0011105]; US EPA STAR [FP-91761701-0]; Drefyus Foundation; Austrian Science Fund (FWF) [L518-N20]; DOC-FORTE-fellowship of the Austrian Academy of Science; DOE SBIR [DE-FG02-08ER85160, DE-SC0004577, DE-SC0001666]<br/>Compilation of the multi-instrument data was supported by NOAA grant NA10OAR4310106. Contributions from individual researchers were supported by NOAA NA10OAR4310106 (J.F.H., E.S.C., A.J.C. and J.H.K.); NSF ATM-0919189, NSF AGS-1243354, and DOE DE-SC0011105 (D.A.D., R.L.N.Y., P.L.H., B.B.P., P.C.-J., H.S. and J.L.J.); US EPA STAR Graduate Fellowship FP-91761701-0 (B.B.P.); NSF RAPID 1135745 (A.W.H.C., Y.Z. and A.H.G.); the Drefyus Foundation (E.S.C.); Austrian Science Fund (FWF) project number L518-N20 (A.H. and L.K.) DOC-FORTE-fellowship of the Austrian Academy of Science (L.K.) and NSF AGS-1238109 (C.L.H.). The SV-TAG, CIMS, and TD EIMS were developed with support from the DOE SBIR program, grants DE-FG02-08ER85160, DE-FG02-08ER85160, DE-SC0004577, and DE-SC0001666. The authors are grateful to A. Turnipseed and the management of the Manitou Experimental Forest Observatory for field support, to N. Grossberg and B. Lefer for their measurements of boundary layer heights, to N. Kreisberg and S. Hering for their development and support of the SV-TAG, and to A. Steiner for helpful discussions regarding vertical mixing.<br/>Nature publishing group<br/>New york},
 folder_uuids = {d013c061-b5b7-4df2-8907-4cdb256c465f},
 private_publication = {false},
 abstract = {Atmospheric organic compounds are central to key chemical processes that influence air quality, ecological health, and climate. However, longstanding difficulties in predicting important quantities such as organic aerosol formation and oxidant lifetimes indicate that our understanding of atmospheric organic chemistry is fundamentally incomplete, probably due in part to the presence of organic species that are unmeasured using standard analytical techniques. Here we present measurements of a wide range of atmospheric organic compounds - including previously unmeasured species - taken concurrently at a single site (a ponderosa pine forest during summertime) by five state-of-the-art mass spectrometric instruments. The combined data set provides a comprehensive characterization of atmospheric organic carbon, covering a wide range in chemical properties (volatility, oxidation state, and molecular size), and exhibiting no obvious measurement gaps. This enables the first construction of a measurement-based local organic budget, highlighting the high emission, deposition, and oxidation fluxes in this environment. Moreover, previously unmeasured species, including semivolatile and intermediate-volatility organic species (S/IVOCs), account for one-third of the total organic carbon, and (within error) provide closure on both OH reactivity and potential secondary organic aerosol formation.},
 bibtype = {article},
 author = {Hunter, James F. and Day, Douglas A. and Palm, Brett B. and Yatavelli, Reddy L.N. and Chan, Arthur W.H. and Kaser, Lisa and Cappellin, Luca and Hayes, Patrick L. and Cross, Eben S. and Carrasquillo, Anthony J. and Campuzano-Jost, Pedro and Stark, Harald and Zhao, Yunliang and Hohaus, Thorsten and Smith, James N. and Hansel, Armin and Karl, Thomas and Goldstein, Allen H. and Guenther, Alex and Worsnop, Douglas R. and Thornton, Joel A. and Heald, Colette L. and Jimenez, Jose L. and Kroll, Jesse H.},
 doi = {10.1038/NGEO3018},
 journal = {Nature Geoscience},
 number = {10}
}

Atmospheric organic compounds are central to key chemical processes that influence air quality, ecological health, and climate. However, longstanding difficulties in predicting important quantities such as organic aerosol formation and oxidant lifetimes indicate that our understanding of atmospheric organic chemistry is fundamentally incomplete, probably due in part to the presence of organic species that are unmeasured using standard analytical techniques. Here we present measurements of a wide range of atmospheric organic compounds - including previously unmeasured species - taken concurrently at a single site (a ponderosa pine forest during summertime) by five state-of-the-art mass spectrometric instruments. The combined data set provides a comprehensive characterization of atmospheric organic carbon, covering a wide range in chemical properties (volatility, oxidation state, and molecular size), and exhibiting no obvious measurement gaps. This enables the first construction of a measurement-based local organic budget, highlighting the high emission, deposition, and oxidation fluxes in this environment. Moreover, previously unmeasured species, including semivolatile and intermediate-volatility organic species (S/IVOCs), account for one-third of the total organic carbon, and (within error) provide closure on both OH reactivity and potential secondary organic aerosol formation.

@article{
 title = {Ethene, propene, butene and isoprene emissions from a ponderosa pine forest measured by relaxed eddy accumulation},
 type = {article},
 year = {2017},
 pages = {13417-13438},
 volume = {17},
 websites = {https://www.atmos-chem-phys.net/17/13417/2017/},
 id = {dd8ff5b8-045f-328f-814a-42766bedc51e},
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 citation_key = {Rhew2017},
 source_type = {JOUR},
 notes = {ACP},
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 abstract = {Alkenes are reactive hydrocarbons that influence local and regional atmospheric chemistry by playing important roles in the photochemical production of tropospheric ozone and in the formation of secondary organic aerosols. The simplest alkene, ethene (ethylene), is a major plant hormone and ripening agent for agricultural commodities. The group of light alkenes (C2-C4) originates from both biogenic and anthropogenic sources, but their biogenic sources are poorly characterized, with limited field-based flux observations. Here we report net ecosystem fluxes of light alkenes and isoprene from a semiarid ponderosa pine forest in the Rocky Mountains of Colorado, USA using the relaxed eddy accumulation (REA) technique during the summer of 2014. Ethene, propene, butene and isoprene emissions have strong diurnal cycles, with median daytime fluxes of 123, 95, 39 and 17 μg mg-2 hg-1, respectively. The fluxes were correlated with each other, followed general ecosystem trends of CO2 and water vapor, and showed similar sunlight and temperature response curves as other biogenic VOCs. The May through October flux, based on measurements and modeling, averaged 62, 52, 24 and 18 μg mg-2 hg-1 for ethene, propene, butene and isoprene, respectively. The light alkenes contribute significantly to the overall biogenic source of reactive hydrocarbons: roughly 18 % of the dominant biogenic VOC, 2-methyl-3-buten-2-ol. The measured ecosystem scale fluxes are 40-80 % larger than estimates used for global emissions models for this type of ecosystem.},
 bibtype = {article},
 author = {Rhew, Robert C. and Deventer, Malte Julian and Turnipseed, Andrew A. and Warneke, Carsten and Ortega, John and Shen, Steve and Martinez, Luis and Koss, Abigail and Lerner, Brian M. and Gilman, Jessica B. and Smith, James N. and Guenther, Alex B. and De Gouw, Joost A.},
 doi = {10.5194/acp-17-13417-2017},
 journal = {Atmospheric Chemistry and Physics},
 number = {21}
}

Alkenes are reactive hydrocarbons that influence local and regional atmospheric chemistry by playing important roles in the photochemical production of tropospheric ozone and in the formation of secondary organic aerosols. The simplest alkene, ethene (ethylene), is a major plant hormone and ripening agent for agricultural commodities. The group of light alkenes (C2-C4) originates from both biogenic and anthropogenic sources, but their biogenic sources are poorly characterized, with limited field-based flux observations. Here we report net ecosystem fluxes of light alkenes and isoprene from a semiarid ponderosa pine forest in the Rocky Mountains of Colorado, USA using the relaxed eddy accumulation (REA) technique during the summer of 2014. Ethene, propene, butene and isoprene emissions have strong diurnal cycles, with median daytime fluxes of 123, 95, 39 and 17 μg mg-2 hg-1, respectively. The fluxes were correlated with each other, followed general ecosystem trends of CO2 and water vapor, and showed similar sunlight and temperature response curves as other biogenic VOCs. The May through October flux, based on measurements and modeling, averaged 62, 52, 24 and 18 μg mg-2 hg-1 for ethene, propene, butene and isoprene, respectively. The light alkenes contribute significantly to the overall biogenic source of reactive hydrocarbons: roughly 18 % of the dominant biogenic VOC, 2-methyl-3-buten-2-ol. The measured ecosystem scale fluxes are 40-80 % larger than estimates used for global emissions models for this type of ecosystem.

@article{
 title = {Sources of particulate organic nitrates in the boreal forest in Finland},
 type = {article},
 year = {2017},
 pages = {13-26},
 volume = {22},
 websites = {http://www.borenv.net/BER/pdfs/ber22/ber22-013-026-Kortelainen.pdf},
 id = {dbd918ca-6823-3adf-bba3-9513cbe13961},
 created = {2020-08-21T23:00:42.235Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-11-02T20:28:33.482Z},
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 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Kortelainen2017},
 source_type = {JOUR},
 private_publication = {false},
 abstract = {Organic nitrates (ON) are known to be present in secondary organic aerosol and act as a reservoir of nitrogen oxides, regulating the local and regional ozone and hydroxyl radical budgets. This work reports observations of particulate ON in Finnish remote boreal forest at a site with dominant emissions from biogenic volatile organic compounds. High Resolution- Aerosol Mass Spectrometer data were analysed in a unique way to characterize the sources of inorganic and organic nitrates. ON were found to be related to local sources with semi-volatile properties. Also they were implying a nocturnal formation mechanism. Occasionally, local sawmill emissions contributed greatly to the organic nitrates. The observations indicated that in the remote boreal forest area the NO3 radicals are oxidizing biogenic VOCs producing ON. This work demonstrates the significant impact of anthropogenic-biogenic emissions interaction on the atmospheric organic nitrate aerosol mass concentration.},
 bibtype = {article},
 author = {Kortelainen, Aki and Hao, Liqing and Tiitta, Petri and Jaatinen, Antti and Miettinen, Pasi and Kulmala, Markku and Smith, James N. and Laaksonen, Ari and Worsnop, Douglas R. and Virtanen, Annele},
 journal = {Boreal Environment Research}
}

Organic nitrates (ON) are known to be present in secondary organic aerosol and act as a reservoir of nitrogen oxides, regulating the local and regional ozone and hydroxyl radical budgets. This work reports observations of particulate ON in Finnish remote boreal forest at a site with dominant emissions from biogenic volatile organic compounds. High Resolution- Aerosol Mass Spectrometer data were analysed in a unique way to characterize the sources of inorganic and organic nitrates. ON were found to be related to local sources with semi-volatile properties. Also they were implying a nocturnal formation mechanism. Occasionally, local sawmill emissions contributed greatly to the organic nitrates. The observations indicated that in the remote boreal forest area the NO3 radicals are oxidizing biogenic VOCs producing ON. This work demonstrates the significant impact of anthropogenic-biogenic emissions interaction on the atmospheric organic nitrate aerosol mass concentration.

@article{
 title = {Recent advances in understanding secondary organic aerosol: Implications for global climate forcing},
 type = {article},
 year = {2017},
 keywords = {secondary organic aerosol},
 pages = {509-559},
 volume = {55},
 id = {1935e67c-3822-3cf7-a1f9-80265a1a8c02},
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 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Shrivastava2017},
 private_publication = {false},
 abstract = {Anthropogenic emissions and land use changes have modified atmospheric aerosol concentrations and size distributions over time. Understanding preindustrial conditions and changes in organic aerosol due to anthropogenic activities is important because these features (1) influence estimates of aerosol radiative forcing and (2) can confound estimates of the historical response of climate to increases in greenhouse gases. Secondary organic aerosol (SOA), formed in the atmosphere by oxidation of organic gases, represents a major fraction of global submicron-sized atmospheric organic aerosol. Over the past decade, significant advances in understanding SOA properties and formation mechanisms have occurred through measurements, yet current climate models typically do not comprehensively include all important processes. This review summarizes some of the important developments during the past decade in understanding SOA formation. We highlight the importance of some processes that influence the growth of SOA particles to sizes relevant for clouds and radiative forcing, including formation of extremely low volatility organics in the gas phase, acid-catalyzed multiphase chemistry of isoprene epoxydiols, particle-phase oligomerization, and physical properties such as volatility and viscosity. Several SOA processes highlighted in this review are complex and interdependent and have nonlinear effects on the properties, formation, and evolution of SOA. Current global models neglect this complexity and nonlinearity and thus are less likely to accurately predict the climate forcing of SOA and project future climate sensitivity to greenhouse gases. Efforts are also needed to rank the most influential processes and nonlinear process-related interactions, so that these processes can be accurately represented in atmospheric chemistry-climate models.},
 bibtype = {article},
 author = {Shrivastava, Manish and Cappa, Christopher D. and Fan, Jiwen and Goldstein, Allen H. and Guenther, Alex B. and Jimenez, Jose L. and Kuang, Chongai and Laskin, Alexander and Martin, Scot T. and Ng, Nga Lee and Petaja, Tuukka and Pierce, Jeffrey R. and Rasch, Philip J. and Roldin, Pontus and Seinfeld, John H. and Shilling, John and Smith, James N. and Thornton, Joel A. and Volkamer, Rainer and Wang, Jian and Worsnop, Douglas R. and Zaveri, Rahul A. and Zelenyuk, Alla and Zhang, Qi},
 doi = {10.1002/2016RG000540},
 journal = {Reviews of Geophysics},
 number = {2}
}

Anthropogenic emissions and land use changes have modified atmospheric aerosol concentrations and size distributions over time. Understanding preindustrial conditions and changes in organic aerosol due to anthropogenic activities is important because these features (1) influence estimates of aerosol radiative forcing and (2) can confound estimates of the historical response of climate to increases in greenhouse gases. Secondary organic aerosol (SOA), formed in the atmosphere by oxidation of organic gases, represents a major fraction of global submicron-sized atmospheric organic aerosol. Over the past decade, significant advances in understanding SOA properties and formation mechanisms have occurred through measurements, yet current climate models typically do not comprehensively include all important processes. This review summarizes some of the important developments during the past decade in understanding SOA formation. We highlight the importance of some processes that influence the growth of SOA particles to sizes relevant for clouds and radiative forcing, including formation of extremely low volatility organics in the gas phase, acid-catalyzed multiphase chemistry of isoprene epoxydiols, particle-phase oligomerization, and physical properties such as volatility and viscosity. Several SOA processes highlighted in this review are complex and interdependent and have nonlinear effects on the properties, formation, and evolution of SOA. Current global models neglect this complexity and nonlinearity and thus are less likely to accurately predict the climate forcing of SOA and project future climate sensitivity to greenhouse gases. Efforts are also needed to rank the most influential processes and nonlinear process-related interactions, so that these processes can be accurately represented in atmospheric chemistry-climate models.

@article{
 title = {The role of ions in new particle formation in the CLOUD chamber},
 type = {article},
 year = {2017},
 pages = {15181-15197},
 volume = {17},
 websites = {https://www.atmos-chem-phys-discuss.net/acp-2017-536/},
 id = {8b3ebd57-6e0c-3254-8ea0-0c340c6ad2d1},
 created = {2023-01-31T22:46:16.067Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:36.569Z},
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 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Wagner2017},
 source_type = {JOUR},
 notes = {<b>From Duplicate 1 (<i>The role of ions in new particle formation in the CLOUD chamber</i> - Wagner, Robert; Yan, Chao; Lehtipalo, Katrianne; Duplissy, Jonathan; Nieminen, Tuomo; Kangasluoma, Juha; Ahonen, Lauri R.; Dada, Lubna; Kontkanen, Jenni; Manninen, Hanna E.; Dias, Antonio; Amorim, Antonio; Bauer, Paulus S.; Bergen, Anton; Bernhammer, Anne Kathrin; Bianchi, Federico; Brilke, Sophia; Buenrostro Mazon, Stephany; Chen, Xuemeng; Draper, Danielle C.; Fischer, Lukas; Frege, Carla; Fuchs, Claudia; Garmash, Olga; Gordon, Hamish; Hakala, Jani; Heikkinen, Liine; Heinritzi, Martin; Hofbauer, Victoria; Hoyle, Christopher R.; Kirkby, Jasper; Kürten, Andreas; Kvashnin, Alexander N.; Laurila, Tiia; Lawler, Michael J.; Mai, Huajun; Makhmutov, Vladimir; Mauldin, Roy; Molteni, Ugo; Nichman, Leonid; Nie, Wei; Ojdanic, Andrea; Onnela, Antti; Piel, Felix; Quéléver, Lauriane L.J.; Rissanen, Matti P.; Sarnela, Nina; Schallhart, Simon; Sengupta, Kamalika; Simon, Mario; Stolzenburg, Dominik; Stozhkov, Yuri; Tröstl, Jasmin; Viisanen, Yrjö; Vogel, Alexander L.; Wagner, Andrea C.; Xiao, Mao; Ye, Penglin; Baltensperger, Urs; Curtius, Joachim; Donahue, Neil M.; Flagan, Richard C.; Gallagher, Martin; Hansel, Armin; Smith, James N.; Tomé, António; Winkler, Paul M.; Worsnop, Douglas; Ehn, Mikael; Sipilä, Mikko; Kerminen, Veli Matti; Petäjä, Tuukka; Kulmala, Markku)<br/></b><br/><b>From Duplicate 2 (<i>The role of ions in new particle formation in the CLOUD chamber</i> - Wagner, Robert; Yan, Chao; Lehtipalo, Katrianne; Duplissy, Jonathan; Nieminen, Tuomo; Kangasluoma, Juha; Ahonen, Lauri R.; Dada, Lubna; Kontkanen, Jenni; Manninen, Hanna E.; Dias, Antonio; Amorim, Antonio; Bauer, Paulus S.; Bergen, Anton; Bernhammer, Anne Kathrin; Bianchi, Federico; Brilke, Sophia; Buenrostro Mazon, Stephany; Chen, Xuemeng; Draper, Danielle C.; Fischer, Lukas; Frege, Carla; Fuchs, Claudia; Garmash, Olga; Gordon, Hamish; Hakala, Jani; Heikkinen, Liine; Heinritzi, Martin; Hofbauer, Victoria; Hoyle, Christopher R.; Kirkby, Jasper; Kürten, Andreas; Kvashnin, Alexander N.; Laurila, Tiia; Lawler, Michael J.; Mai, Huajun; Makhmutov, Vladimir; Mauldin, Roy; Molteni, Ugo; Nichman, Leonid; Nie, Wei; Ojdanic, Andrea; Onnela, Antti; Piel, Felix; Quéléver, Lauriane L.J.; Rissanen, Matti P.; Sarnela, Nina; Schallhart, Simon; Sengupta, Kamalika; Simon, Mario; Stolzenburg, Dominik; Stozhkov, Yuri; Tröstl, Jasmin; Viisanen, Yrjö; Vogel, Alexander L.; Wagner, Andrea C.; Xiao, Mao; Ye, Penglin; Baltensperger, Urs; Curtius, Joachim; Donahue, Neil M.; Flagan, Richard C.; Gallagher, Martin; Hansel, Armin; Smith, James N.; Tomé, António; Winkler, Paul M.; Worsnop, Douglas; Ehn, Mikael; Sipilä, Mikko; Kerminen, Veli Matti; Petäjä, Tuukka; Kulmala, Markku)<br/></b><br/>ACPD<br/><br/><b>From Duplicate 2 (<i>The role of ions in new particle formation in the CLOUD chamber</i> - Wagner, Robert; Yan, Chao; Lehtipalo, Katrianne; Duplissy, Jonathan; Nieminen, Tuomo; Kangasluoma, Juha; Ahonen, Lauri R.; Dada, Lubna; Kontkanen, Jenni; Manninen, Hanna E.; Dias, Antonio; Amorim, Antonio; Bauer, Paulus S.; Bergen, Anton; Bernhammer, Anne Kathrin; Bianchi, Federico; Brilke, Sophia; Buenrostro Mazon, Stephany; Chen, Xuemeng; Draper, Danielle C.; Fischer, Lukas; Frege, Carla; Fuchs, Claudia; Garmash, Olga; Gordon, Hamish; Hakala, Jani; Heikkinen, Liine; Heinritzi, Martin; Hofbauer, Victoria; Hoyle, Christopher R.; Kirkby, Jasper; Kürten, Andreas; Kvashnin, Alexander N.; Laurila, Tiia; Lawler, Michael J.; Mai, Huajun; Makhmutov, Vladimir; Mauldin, Roy; Molteni, Ugo; Nichman, Leonid; Nie, Wei; Ojdanic, Andrea; Onnela, Antti; Piel, Felix; Quéléver, Lauriane L.J.; Rissanen, Matti P.; Sarnela, Nina; Schallhart, Simon; Sengupta, Kamalika; Simon, Mario; Stolzenburg, Dominik; Stozhkov, Yuri; Tröstl, Jasmin; Viisanen, Yrjö; Vogel, Alexander L.; Wagner, Andrea C.; Xiao, Mao; Ye, Penglin; Baltensperger, Urs; Curtius, Joachim; Donahue, Neil M.; Flagan, Richard C.; Gallagher, Martin; Hansel, Armin; Smith, James N.; Tomé, António; Winkler, Paul M.; Worsnop, Douglas; Ehn, Mikael; Sipilä, Mikko; Kerminen, Veli Matti; Petäjä, Tuukka; Kulmala, Markku)<br/></b><br/>ACPD},
 folder_uuids = {e9db4589-c14d-471c-8b7a-bb4b8e16be27},
 private_publication = {false},
 abstract = {The formation of secondary particles in the atmosphere accounts for more than half of global cloud condensation nuclei. Experiments at the CERN CLOUD (Cosmics Leaving OUtdoor Droplets) chamber have underlined the importance of ions for new particle formation, but quantifying their effect in the atmosphere remains challenging. By using a novel instrument setup consisting of two nanoparticle counters, one of them equipped with an ion filter, we were able to further investigate the ion-related mechanisms of new particle formation. In autumn 2015, we carried out experiments at CLOUD on four systems of different chemical compositions involving monoterpenes, sulfuric acid, nitrogen oxides, and ammonia. We measured the influence of ions on the nucleation rates under precisely controlled and atmospherically relevant conditions. Our results indicate that ions enhance the nucleation process when the charge is necessary to stabilize newly formed clusters, i.e., in conditions in which neutral clusters are unstable. For charged clusters that were formed by ion-induced nucleation, we were able to measure, for the first time, their progressive neutralization due to recombination with oppositely charged ions. A large fraction of the clusters carried a charge at 1.5 nm diameter. However, depending on particle growth rates and ion concentrations, charged clusters were largely neutralized by ion-ion recombination before they grew to 2.5 nm. At this size, more than 90 % of particles were neutral. In other words, particles may originate from ion-induced nucleation, although they are neutral upon detection at diameters larger than 2.5 nm. Observations at Hyytiälä, Finland, showed lower ion concentrations and a lower contribution of ion-induced nucleation than measured at CLOUD under similar conditions. Although this can be partly explained by the observation that ion-induced fractions decrease towards lower ion concentrations, further investigations are needed to resolve the origin of the discrepancy.},
 bibtype = {article},
 author = {Wagner, Robert and Yan, Chao and Lehtipalo, Katrianne and Duplissy, Jonathan and Nieminen, Tuomo and Kangasluoma, Juha and Ahonen, Lauri R. and Dada, Lubna and Kontkanen, Jenni and Manninen, Hanna E. and Dias, Antonio and Amorim, Antonio and Bauer, Paulus S. and Bergen, Anton and Bernhammer, Anne Kathrin and Bianchi, Federico and Brilke, Sophia and Buenrostro Mazon, Stephany and Chen, Xuemeng and Draper, Danielle C. and Fischer, Lukas and Frege, Carla and Fuchs, Claudia and Garmash, Olga and Gordon, Hamish and Hakala, Jani and Heikkinen, Liine and Heinritzi, Martin and Hofbauer, Victoria and Hoyle, Christopher R. and Kirkby, Jasper and Kürten, Andreas and Kvashnin, Alexander N. and Laurila, Tiia and Lawler, Michael J. and Mai, Huajun and Makhmutov, Vladimir and Mauldin, Roy and Molteni, Ugo and Nichman, Leonid and Nie, Wei and Ojdanic, Andrea and Onnela, Antti and Piel, Felix and Quéléver, Lauriane L.J. and Rissanen, Matti P. and Sarnela, Nina and Schallhart, Simon and Sengupta, Kamalika and Simon, Mario and Stolzenburg, Dominik and Stozhkov, Yuri and Tröstl, Jasmin and Viisanen, Yrjö and Vogel, Alexander L. and Wagner, Andrea C. and Xiao, Mao and Ye, Penglin and Baltensperger, Urs and Curtius, Joachim and Donahue, Neil M. and Flagan, Richard C. and Gallagher, Martin and Hansel, Armin and Smith, James N. and Tomé, António and Winkler, Paul M. and Worsnop, Douglas and Ehn, Mikael and Sipilä, Mikko and Kerminen, Veli Matti and Petäjä, Tuukka and Kulmala, Markku},
 doi = {10.5194/acp-17-15181-2017},
 journal = {Atmospheric Chemistry and Physics},
 number = {24}
}

The formation of secondary particles in the atmosphere accounts for more than half of global cloud condensation nuclei. Experiments at the CERN CLOUD (Cosmics Leaving OUtdoor Droplets) chamber have underlined the importance of ions for new particle formation, but quantifying their effect in the atmosphere remains challenging. By using a novel instrument setup consisting of two nanoparticle counters, one of them equipped with an ion filter, we were able to further investigate the ion-related mechanisms of new particle formation. In autumn 2015, we carried out experiments at CLOUD on four systems of different chemical compositions involving monoterpenes, sulfuric acid, nitrogen oxides, and ammonia. We measured the influence of ions on the nucleation rates under precisely controlled and atmospherically relevant conditions. Our results indicate that ions enhance the nucleation process when the charge is necessary to stabilize newly formed clusters, i.e., in conditions in which neutral clusters are unstable. For charged clusters that were formed by ion-induced nucleation, we were able to measure, for the first time, their progressive neutralization due to recombination with oppositely charged ions. A large fraction of the clusters carried a charge at 1.5 nm diameter. However, depending on particle growth rates and ion concentrations, charged clusters were largely neutralized by ion-ion recombination before they grew to 2.5 nm. At this size, more than 90 % of particles were neutral. In other words, particles may originate from ion-induced nucleation, although they are neutral upon detection at diameters larger than 2.5 nm. Observations at Hyytiälä, Finland, showed lower ion concentrations and a lower contribution of ion-induced nucleation than measured at CLOUD under similar conditions. Although this can be partly explained by the observation that ion-induced fractions decrease towards lower ion concentrations, further investigations are needed to resolve the origin of the discrepancy.

@article{
 title = {Modeling the thermodynamics and kinetics of sulfuric acid-dimethylamine-water nanoparticle growth in the CLOUD chamber},
 type = {article},
 year = {2016},
 pages = {1017-1032},
 volume = {50},
 websites = {https://www.tandfonline.com/doi/full/10.1080/02786826.2016.1223268},
 month = {10},
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 id = {948390ba-2ed6-31a6-a425-d16a0690eeb4},
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 folder_uuids = {e9db4589-c14d-471c-8b7a-bb4b8e16be27},
 private_publication = {false},
 abstract = {Dimethylamine (DMA) has a stabilizing effect on sulfuric acid (SA) clusters, and the SA and DMA molecules and clusters likely play important roles in both aerosol particle formation and growth in the atmosphere. We use the monodisperse particle growth model for acid-base chemistry in nanoparticle growth (MABNAG) together with direct and indirect observations from the CLOUD4 and CLOUD7 experiments in the cosmics leaving outdoor droplets (CLOUD) chamber at CERN to investigate the size and composition evolution of freshly formed particles consisting of SA, DMA, and water as they grow to 20 nm in dry diameter. Hygroscopic growth factors are measured using a nano-hygroscopicity tandem differential mobility analyzer (nano-HTDMA), which combined with simulations of particle water uptake using the thermodynamic extended-aerosol inorganics model (E-AIM) constrain the chemical composition. MABNAG predicts a particle-phase ratio between DMA and SA molecules of 1.1–1.3 for a 2 nm particle and DMA gas-phase mixing ratios between 3.5 and 80 pptv. These ratios agree well with observations by an atmospheric-pressure interface time-of-flight (APi-TOF) mass spectrometer. Simulations with MABNAG, direct observations of the composition of clusters <2 nm, and indirect observations of the particle composition indicate that the acidity of the nucleated particles decreases as they grow from ∼1 to 20 nm. However, MABNAG predicts less acidic particles than suggested by the indirect estimates at 10 nm diameter using the nano-HTDMA measurements, and less acidic particles than observed by a thermal desorption chemical ionization mass spectrometer (TDCIMS) at 10–30 nm. Possible explanations for these discrepancies are discussed. Copyright © 2016 American Association for Aerosol Research},
 bibtype = {article},
 author = {Ahlm, L. and Yli-Juuti, T. and Schobesberger, S. and Praplan, A. P. and Kim, J. and Tikkanen, O. P. and Lawler, M. J. and Smith, J. N. and Tröstl, J. and Acosta Navarro, J. C. and Baltensperger, U. and Bianchi, F. and Donahue, N. M. and Duplissy, J. and Franchin, A. and Jokinen, T. and Keskinen, H. and Kirkby, J. and Kürten, A. and Laaksonen, A. and Lehtipalo, K. and Petäjä, T. and Riccobono, F. and Rissanen, M. P. and Rondo, L. and Schallhart, S. and Simon, M. and Winkler, P. M. and Worsnop, D. R. and Virtanen, A. and Riipinen, I.},
 doi = {10.1080/02786826.2016.1223268},
 journal = {Aerosol Science and Technology},
 number = {10}
}

Dimethylamine (DMA) has a stabilizing effect on sulfuric acid (SA) clusters, and the SA and DMA molecules and clusters likely play important roles in both aerosol particle formation and growth in the atmosphere. We use the monodisperse particle growth model for acid-base chemistry in nanoparticle growth (MABNAG) together with direct and indirect observations from the CLOUD4 and CLOUD7 experiments in the cosmics leaving outdoor droplets (CLOUD) chamber at CERN to investigate the size and composition evolution of freshly formed particles consisting of SA, DMA, and water as they grow to 20 nm in dry diameter. Hygroscopic growth factors are measured using a nano-hygroscopicity tandem differential mobility analyzer (nano-HTDMA), which combined with simulations of particle water uptake using the thermodynamic extended-aerosol inorganics model (E-AIM) constrain the chemical composition. MABNAG predicts a particle-phase ratio between DMA and SA molecules of 1.1–1.3 for a 2 nm particle and DMA gas-phase mixing ratios between 3.5 and 80 pptv. These ratios agree well with observations by an atmospheric-pressure interface time-of-flight (APi-TOF) mass spectrometer. Simulations with MABNAG, direct observations of the composition of clusters <2 nm, and indirect observations of the particle composition indicate that the acidity of the nucleated particles decreases as they grow from ∼1 to 20 nm. However, MABNAG predicts less acidic particles than suggested by the indirect estimates at 10 nm diameter using the nano-HTDMA measurements, and less acidic particles than observed by a thermal desorption chemical ionization mass spectrometer (TDCIMS) at 10–30 nm. Possible explanations for these discrepancies are discussed. Copyright © 2016 American Association for Aerosol Research

@article{
 title = {Global atmospheric particle formation from CERN CLOUD measurements},
 type = {article},
 year = {2016},
 pages = {1119-1124},
 volume = {354},
 websites = {http://www.sciencemag.org/cgi/doi/10.1126/science.aaf2649},
 id = {6e2c840e-04f5-3550-976c-9deee6afa58c},
 created = {2017-04-12T23:44:38.121Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-08-21T23:00:49.316Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Dunne2016},
 source_type = {article},
 folder_uuids = {e9db4589-c14d-471c-8b7a-bb4b8e16be27},
 private_publication = {false},
 abstract = {Fundamental questions remain about the origin of newly formed atmospheric aerosol particles because data from laboratory measurements have been insufficient to build global models. In contrast, gas-phase chemistry models have been based on laboratory kinetics measurements for decades. We built a global model of aerosol formation by using extensive laboratory measurements of rates of nucleation involving sulfuric acid, ammonia, ions, and organic compounds conducted in the CERN CLOUD (Cosmics Leaving Outdoor Droplets) chamber. The simulations and a comparison with atmospheric observations show that nearly all nucleation throughout the present-day atmosphere involves ammonia or biogenic organic compounds, in addition to sulfuric acid. A considerable fraction of nucleation involves ions, but the relatively weak dependence on ion concentrations indicates that for the processes studied, variations in cosmic ray intensity do not appreciably affect climate through nucleation in the present-day atmosphere.},
 bibtype = {article},
 author = {Dunne, Eimear M. and Gordon, Hamish and Kürten, Andreas and Almeida, João and Duplissy, Jonathan and Williamson, Christina and Ortega, Ismael K. and Pringle, Kirsty J. and Adamov, Alexey and Baltensperger, Urs and Barmet, Peter and Benduhn, Francois and Bianchi, Federico and Breitenlechner, Martin and Clarke, Antony and Curtius, Joachim and Dommen, Josef and Donahue, Neil M. and Ehrhart, Sebastian and Flagan, Richard C. and Franchin, Alessandro and Guida, Roberto and Hakala, Jani and Hansel, Armin and Heinritzi, Martin and Jokinen, Tuija and Kangasluoma, Juha and Kirkby, Jasper and Kulmala, Markku and Kupc, Agnieszka and Lawler, Michael J. and Lehtipalo, Katrianne and Makhmutov, Vladimir and Mann, Graham and Mathot, Serge and Merikanto, Joonas and Miettinen, Pasi and Nenes, Athanasios and Onnela, Antti and Rap, Alexandru and Reddington, Carly L.S. and Riccobono, Francesco and Richards, Nigel A.D. and Rissanen, Matti P. and Rondo, Linda and Sarnela, Nina and Schobesberger, Siegfried and Sengupta, Kamalika and Simon, Mario and Sipilä, Mikko and Smith, James N. and Stozkhov, Yuri and Tomé, Antonio and Tröstl, Jasmin and Wagner, Paul E. and Wimmer, Daniela and Winkler, Paul M. and Worsnop, Douglas R. and Carslaw, Kenneth S.},
 doi = {10.1126/science.aaf2649},
 journal = {Science},
 number = {6316}
}

Fundamental questions remain about the origin of newly formed atmospheric aerosol particles because data from laboratory measurements have been insufficient to build global models. In contrast, gas-phase chemistry models have been based on laboratory kinetics measurements for decades. We built a global model of aerosol formation by using extensive laboratory measurements of rates of nucleation involving sulfuric acid, ammonia, ions, and organic compounds conducted in the CERN CLOUD (Cosmics Leaving Outdoor Droplets) chamber. The simulations and a comparison with atmospheric observations show that nearly all nucleation throughout the present-day atmosphere involves ammonia or biogenic organic compounds, in addition to sulfuric acid. A considerable fraction of nucleation involves ions, but the relatively weak dependence on ion concentrations indicates that for the processes studied, variations in cosmic ray intensity do not appreciably affect climate through nucleation in the present-day atmosphere.

@article{
 title = {Technical note: An improved approach to determining background aerosol concentrations with PILS sampling on aircraft},
 type = {article},
 year = {2016},
 keywords = {Background correction,Blank,FRAPPÉ,Limit of detection},
 pages = {16-20},
 volume = {136},
 websites = {http://linkinghub.elsevier.com/retrieve/pii/S135223101630262X},
 month = {7},
 id = {e7ce2a43-cdc6-33ef-953a-f5d6e5b8b384},
 created = {2017-04-12T23:44:38.314Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-08-21T23:00:50.023Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Fukami2016},
 source_type = {article},
 private_publication = {false},
 abstract = {Particle-into-Liquid Samplers (PILS) have become a standard aerosol collection technique, and are widely used in both ground and aircraft measurements in conjunction with off-line ion chromatography (IC) measurements. Accurate and precise background samples are essential to account for gas-phase components not efficiently removed and any interference in the instrument lines, collection vials or off-line analysis procedures. For aircraft sampling with PILS, backgrounds are typically taken with in-line filters to remove particles prior to sample collection once or twice per flight with more numerous backgrounds taken on the ground. Here, we use data collected during the Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ) to demonstrate that not only are multiple background filter samples are essential to attain a representative background, but that the chemical background signals do not follow the Gaussian statistics typically assumed. Instead, the background signals for all chemical components analyzed from 137 background samples (taken from ~78 total sampling hours over 18 flights) follow a log-normal distribution, meaning that the typical approaches of averaging background samples and/or assuming a Gaussian distribution cause an over-estimation of background samples - and thus an underestimation of sample concentrations. Our approach of deriving backgrounds from the peak of the log-normal distribution results in detection limits of 0.25, 0.32, 3.9, 0.17, 0.75 and 0.57 μg m-3 for sub-micron aerosol nitrate (NO3-), nitrite (NO2-), ammonium (NH4+), sulfate (SO42-), potassium (K+) and calcium (Ca2+), respectively. The difference in backgrounds calculated from assuming a Gaussian distribution versus a log-normal distribution were most extreme for NH4+, resulting in a background that was 1.58× that determined from fitting a log-normal distribution.},
 bibtype = {article},
 author = {Fukami, Christine S. and Sullivan, Amy P. and Ryan Fulgham, S. and Murschell, Trey and Borch, Thomas and Smith, James N. and Farmer, Delphine K.},
 doi = {10.1016/j.atmosenv.2016.04.005},
 journal = {Atmospheric Environment}
}

Particle-into-Liquid Samplers (PILS) have become a standard aerosol collection technique, and are widely used in both ground and aircraft measurements in conjunction with off-line ion chromatography (IC) measurements. Accurate and precise background samples are essential to account for gas-phase components not efficiently removed and any interference in the instrument lines, collection vials or off-line analysis procedures. For aircraft sampling with PILS, backgrounds are typically taken with in-line filters to remove particles prior to sample collection once or twice per flight with more numerous backgrounds taken on the ground. Here, we use data collected during the Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ) to demonstrate that not only are multiple background filter samples are essential to attain a representative background, but that the chemical background signals do not follow the Gaussian statistics typically assumed. Instead, the background signals for all chemical components analyzed from 137 background samples (taken from ~78 total sampling hours over 18 flights) follow a log-normal distribution, meaning that the typical approaches of averaging background samples and/or assuming a Gaussian distribution cause an over-estimation of background samples - and thus an underestimation of sample concentrations. Our approach of deriving backgrounds from the peak of the log-normal distribution results in detection limits of 0.25, 0.32, 3.9, 0.17, 0.75 and 0.57 μg m-3 for sub-micron aerosol nitrate (NO3-), nitrite (NO2-), ammonium (NH4+), sulfate (SO42-), potassium (K+) and calcium (Ca2+), respectively. The difference in backgrounds calculated from assuming a Gaussian distribution versus a log-normal distribution were most extreme for NH4+, resulting in a background that was 1.58× that determined from fitting a log-normal distribution.

@article{
 title = {Multiple new-particle growth pathways observed at the US DOE Southern Great Plains field site},
 type = {article},
 year = {2016},
 pages = {9321-9348},
 volume = {16},
 websites = {http://www.atmos-chem-phys.net/16/9321/2016/},
 month = {7},
 day = {28},
 id = {c7c40005-2738-326b-9a14-f5b25acdb64a},
 created = {2017-04-12T23:44:38.558Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-08-21T23:00:50.157Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Hodshire2016},
 source_type = {article},
 folder_uuids = {e9db4589-c14d-471c-8b7a-bb4b8e16be27},
 private_publication = {false},
 abstract = {New-particle formation (NPF) is a significant source of aerosol particles into the atmosphere. However, these particles are initially too small to have climatic importance and must grow, primarily through net uptake of low-volatility species, from diameters ∼ 1 to 30-100 nm in order to potentially impact climate. There are currently uncertainties in the physical and chemical processes associated with the growth of these freshly formed particles that lead to uncertainties in aerosol-climate modeling. Four main pathways for new-particle growth have been identified: condensation of sulfuric-acid vapor (and associated bases when available), condensation of organic vapors, uptake of organic acids through acid-base chemistry in the particle phase, and accretion of organic molecules in the particle phase to create a lower-volatility compound that then contributes to the aerosol mass. The relative importance of each pathway is uncertain and is the focus of this work. The 2013 New Particle Formation Study (NPFS) measurement campaign took place at the DOE Southern Great Plains (SGP) facility in Lamont, Oklahoma, during spring 2013. Measured gas-and particle-phase compositions during these new-particle growth events suggest three distinct growth pathways: (1) growth by primarily organics, (2) growth by primarily sulfuric acid and ammonia, and (3) growth by primarily sulfuric acid and associated bases and organics. To supplement the measurements, we used the particle growth model MABNAG (Model for Acid-Base chemistry in NAnoparticle Growth) to gain further insight into the growth processes on these 3 days at SGP. MABNAG simulates growth from (1) sulfuric-acid condensation (and subsequent salt formation with ammonia or amines), (2) near-irreversible condensation from nonreactive extremely low-volatility organic compounds (ELVOCs), and (3) organic-acid condensation and subsequent salt formation with ammonia or amines. MABNAG is able to corroborate the observed differing growth pathways, while also predicting that ELVOCs contribute more to growth than organic salt formation. However, most MABNAG model simulations tend to underpredict the observed growth rates between 10 and 20 nm in diameter; this underprediction may come from neglecting the contributions to growth from semi-to-low-volatility species or accretion reactions. Our results suggest that in addition to sulfuric acid, ELVOCs are also very important for growth in this rural setting. We discuss the limitations of our study that arise from not accounting for semi-and low-volatility organics, as well as nitrogen-containing species beyond ammonia and amines in the model. Quantitatively understanding the overall budget, evolution, and thermodynamic properties of lower-volatility organics in the atmosphere will be essential for improving global aerosol models.},
 bibtype = {article},
 author = {Hodshire, Anna L. and Lawler, Michael J. and Zhao, Jun and Ortega, John and Jen, Coty and Yli-Juuti, Taina and Brewer, Jared F. and Kodros, Jack K. and Barsanti, Kelley C. and Hanson, Dave R. and McMurry, Peter H. and Smith, James N. and Pierce, Jeffery R.},
 doi = {10.5194/acp-16-9321-2016},
 journal = {Atmospheric Chemistry and Physics},
 number = {14}
}

New-particle formation (NPF) is a significant source of aerosol particles into the atmosphere. However, these particles are initially too small to have climatic importance and must grow, primarily through net uptake of low-volatility species, from diameters ∼ 1 to 30-100 nm in order to potentially impact climate. There are currently uncertainties in the physical and chemical processes associated with the growth of these freshly formed particles that lead to uncertainties in aerosol-climate modeling. Four main pathways for new-particle growth have been identified: condensation of sulfuric-acid vapor (and associated bases when available), condensation of organic vapors, uptake of organic acids through acid-base chemistry in the particle phase, and accretion of organic molecules in the particle phase to create a lower-volatility compound that then contributes to the aerosol mass. The relative importance of each pathway is uncertain and is the focus of this work. The 2013 New Particle Formation Study (NPFS) measurement campaign took place at the DOE Southern Great Plains (SGP) facility in Lamont, Oklahoma, during spring 2013. Measured gas-and particle-phase compositions during these new-particle growth events suggest three distinct growth pathways: (1) growth by primarily organics, (2) growth by primarily sulfuric acid and ammonia, and (3) growth by primarily sulfuric acid and associated bases and organics. To supplement the measurements, we used the particle growth model MABNAG (Model for Acid-Base chemistry in NAnoparticle Growth) to gain further insight into the growth processes on these 3 days at SGP. MABNAG simulates growth from (1) sulfuric-acid condensation (and subsequent salt formation with ammonia or amines), (2) near-irreversible condensation from nonreactive extremely low-volatility organic compounds (ELVOCs), and (3) organic-acid condensation and subsequent salt formation with ammonia or amines. MABNAG is able to corroborate the observed differing growth pathways, while also predicting that ELVOCs contribute more to growth than organic salt formation. However, most MABNAG model simulations tend to underpredict the observed growth rates between 10 and 20 nm in diameter; this underprediction may come from neglecting the contributions to growth from semi-to-low-volatility species or accretion reactions. Our results suggest that in addition to sulfuric acid, ELVOCs are also very important for growth in this rural setting. We discuss the limitations of our study that arise from not accounting for semi-and low-volatility organics, as well as nitrogen-containing species beyond ammonia and amines in the model. Quantitatively understanding the overall budget, evolution, and thermodynamic properties of lower-volatility organics in the atmosphere will be essential for improving global aerosol models.

@article{
 title = {Molecular composition of organic aerosols in central Amazonia: An ultra-high-resolution mass spectrometry study},
 type = {article},
 year = {2016},
 pages = {11899-11913},
 volume = {16},
 websites = {http://www.atmos-chem-phys-discuss.net/acp-2016-404/},
 id = {738364f9-2ffb-3eec-9e4a-b2ba00b89149},
 created = {2017-04-12T23:44:39.005Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-08-21T23:00:49.289Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Kourtchev2016},
 source_type = {article},
 private_publication = {false},
 abstract = {The Amazon Basin plays key role in atmospheric chemistry, biodiversity and climate change. In this study we applied nanoelectrospray (nanoESI) ultra-high-resolution mass spectrometry (UHRMS) for the analysis of the organic fraction of PM2.5 aerosol samples collected during dry and wet seasons at a site in central Amazonia receiving background air masses, biomass burning and urban pollution. Comprehensive mass spectral data evaluation methods (e.g. Kendrick mass defect, Van Krevelen diagrams, carbon oxidation state and aromaticity equivalent) were used to identify compound classes and mass distributions of the detected species. Nitrogen-and/or sulfur-containing organic species contributed up to 60% of the total identified number of formulae. A large number of molecular formulae in organic aerosol (OA) were attributed to later-generation nitrogen-and sulfur-containing oxidation products, suggesting that OA composition is affected by biomass burning and other, potentially anthropogenic, sources. Isoprene-derived organosulfate (IEPOX-OS) was found to be the most dominant ion in most of the analysed samples and strongly followed the concentration trends of the gas-phase anthropogenic tracers confirming its mixed anthropogenic-biogenic origin. The presence of oxidised aromatic and nitro-aromatic compounds in the samples suggested a strong influence from biomass burning especially during the dry period. Aerosol samples from the dry period and under enhanced biomass burning conditions contained a large number of molecules with high carbon oxidation state and an increased number of aromatic compounds compared to that from the wet period. The results of this work demonstrate that the studied site is influenced not only by biogenic emissions from the forest but also by biomass burning and potentially other anthropogenic emissions from the neighbouring urban environments.},
 bibtype = {article},
 author = {Kourtchev, Ivan and Godoi, Ricardo H.M. and Connors, Sarah and Levine, James G. and Archibald, Alex T. and Godoi, Ana F.L. and Paralovo, Sarah L. and Barbosa, Cybelli G.G. and Souza, Rodrigo A.F. and Manzi, Antonio O. and Seco, Roger and Sjostedt, Steve and Park, Jeong Hoo and Guenther, Alex and Kim, Saewung and Smith, James and Martin, Scot T. and Kalberer, Markus},
 doi = {10.5194/acp-16-11899-2016},
 journal = {Atmospheric Chemistry and Physics},
 number = {18}
}

The Amazon Basin plays key role in atmospheric chemistry, biodiversity and climate change. In this study we applied nanoelectrospray (nanoESI) ultra-high-resolution mass spectrometry (UHRMS) for the analysis of the organic fraction of PM2.5 aerosol samples collected during dry and wet seasons at a site in central Amazonia receiving background air masses, biomass burning and urban pollution. Comprehensive mass spectral data evaluation methods (e.g. Kendrick mass defect, Van Krevelen diagrams, carbon oxidation state and aromaticity equivalent) were used to identify compound classes and mass distributions of the detected species. Nitrogen-and/or sulfur-containing organic species contributed up to 60% of the total identified number of formulae. A large number of molecular formulae in organic aerosol (OA) were attributed to later-generation nitrogen-and sulfur-containing oxidation products, suggesting that OA composition is affected by biomass burning and other, potentially anthropogenic, sources. Isoprene-derived organosulfate (IEPOX-OS) was found to be the most dominant ion in most of the analysed samples and strongly followed the concentration trends of the gas-phase anthropogenic tracers confirming its mixed anthropogenic-biogenic origin. The presence of oxidised aromatic and nitro-aromatic compounds in the samples suggested a strong influence from biomass burning especially during the dry period. Aerosol samples from the dry period and under enhanced biomass burning conditions contained a large number of molecules with high carbon oxidation state and an increased number of aromatic compounds compared to that from the wet period. The results of this work demonstrate that the studied site is influenced not only by biogenic emissions from the forest but also by biomass burning and potentially other anthropogenic emissions from the neighbouring urban environments.

@article{
 title = {The effect of acid-base clustering and ions on the growth of atmospheric nano-particles},
 type = {article},
 year = {2016},
 pages = {11594},
 volume = {7},
 websites = {http://www.nature.com/doifinder/10.1038/ncomms11594},
 id = {cdb45e9d-a849-3bf6-bf17-986e3bf87415},
 created = {2017-04-12T23:44:39.802Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-08-21T23:00:50.448Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Lehtipalo2016},
 source_type = {article},
 private_publication = {false},
 abstract = {The growth of freshly formed aerosol particles can be the bottleneck in their survival to cloud condensation nuclei. It is therefore crucial to understand how particles grow in the atmosphere. Insufficient experimental data has impeded a profound understanding of nano-particle growth under atmospheric conditions. Here we study nano-particle growth in the CLOUD (Cosmics Leaving OUtdoors Droplets) chamber, starting from the formation of molecular clusters. We present measured growth rates at sub-3 nm sizes with different atmospherically relevant concentrations of sulphuric acid, water, ammonia and dimethylamine. We find that atmospheric ions and small acid-base clusters, which are not generally accounted for in the measurement of sulphuric acid vapour, can participate in the growth process, leading to enhanced growth rates. The availability of compounds capable of stabilizing sulphuric acid clusters governs the magnitude of these effects and thus the exact growth mechanism. We bring these observations into a coherent framework and discuss their significance in the atmosphere.},
 bibtype = {article},
 author = {Lehtipalo, Katrianne and Rondo, Linda and Kontkanen, Jenni and Schobesberger, Siegfried and Jokinen, Tuija and Sarnela, Nina and Kürten, Andreas and Ehrhart, Sebastian and Franchin, Alessandro and Nieminen, Tuomo and Riccobono, Francesco and Sipilä, Mikko and Yli-Juuti, Taina and Duplissy, Jonathan and Adamov, Alexey and Ahlm, Lars and Almeida, João and Amorim, Antonio and Bianchi, Federico and Breitenlechner, Martin and Dommen, Josef and Downard, Andrew J. and Dunne, Eimear M. and Flagan, Richard C. and Guida, Roberto and Hakala, Jani and Hansel, Armin and Jud, Werner and Kangasluoma, Juha and Kerminen, Veli Matti and Keskinen, Helmi and Kim, Jaeseok and Kirkby, Jasper and Kupc, Agnieszka and Kupiainen-Määttä, Oona and Laaksonen, Ari and Lawler, Michael J. and Leiminger, Markus and Mathot, Serge and Olenius, Tinja and Ortega, Ismael K. and Onnela, Antti and Petäjä, Tuukka and Praplan, Arnaud and Rissanen, Matti P. and Ruuskanen, Taina and Santos, Filipe D. and Schallhart, Simon and Schnitzhofer, Ralf and Simon, Mario and Smith, James N. and Tröstl, Jasmin and Tsagkogeorgas, Georgios and Tomé, António and Vaattovaara, Petri and Vehkamäki, Hanna and Vrtala, Aron E. and Wagner, Paul E. and Williamson, Christina and Wimmer, Daniela and Winkler, Paul M. and Virtanen, Annele and Donahue, Neil M. and Carslaw, Kenneth S. and Baltensperger, Urs and Riipinen, Ilona and Curtius, Joachim and Worsnop, Douglas R. and Kulmala, Markku},
 doi = {10.1038/ncomms11594},
 journal = {Nature Communications},
 number = {May}
}

The growth of freshly formed aerosol particles can be the bottleneck in their survival to cloud condensation nuclei. It is therefore crucial to understand how particles grow in the atmosphere. Insufficient experimental data has impeded a profound understanding of nano-particle growth under atmospheric conditions. Here we study nano-particle growth in the CLOUD (Cosmics Leaving OUtdoors Droplets) chamber, starting from the formation of molecular clusters. We present measured growth rates at sub-3 nm sizes with different atmospherically relevant concentrations of sulphuric acid, water, ammonia and dimethylamine. We find that atmospheric ions and small acid-base clusters, which are not generally accounted for in the measurement of sulphuric acid vapour, can participate in the growth process, leading to enhanced growth rates. The availability of compounds capable of stabilizing sulphuric acid clusters governs the magnitude of these effects and thus the exact growth mechanism. We bring these observations into a coherent framework and discuss their significance in the atmosphere.

@article{
 title = {Effect of dimethylamine on the gas phase sulfuric acid concentration measured by chemical ionization mass spectrometry},
 type = {article},
 year = {2016},
 keywords = {10.1002/2014JD022963 and sea spray aerosol,aerosol-cloud interactions,cloud condensation nuclei,marine aerosol,stratocumulus clouds,supersaturations},
 pages = {3036-3049},
 volume = {121},
 websites = {http://onlinelibrary.wiley.com/doi/10.1002/2015JD023868/full},
 id = {cbe03ae4-e8a4-3010-8abd-da57889bfe7e},
 created = {2017-04-12T23:44:41.073Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-11-02T20:28:33.956Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Rondo2016},
 source_type = {article},
 folder_uuids = {e9db4589-c14d-471c-8b7a-bb4b8e16be27},
 private_publication = {false},
 abstract = {Sulfuric acid is widely recognized as a very important substance driving atmospheric aerosol nucleation. Based on quantum chemical calculations it has been suggested that the quantitative detection of gas phase sulfuric acid (H2SO4) by use of Chemical Ionization Mass Spectrometry (CIMS) could be biased in the presence of gas phase amines such as dimethylamine (DMA). An experiment (CLOUD7 campaign) was set up at the CLOUD (Cosmics Leaving OUtdoor Droplets) chamber to investigate the quantitative detection of H2SO4 in the presence of dimethylamine by CIMS at atmospherically relevant concentrations. For the first time in the CLOUD experiment, the monomer sulfuric acid concentration was measured by a CIMS and by two CI-APi-TOF (Chemical Ionization-Atmospheric Pressure interface-Time Of Flight) mass spectrometers. In addition, neutral sulfuric acid clusters were measured with the CI-APi-TOFs. The CLOUD7 measurements show that in the presence of dimethylamine (<5 to 70 pptv) the sulfuric acid monomer measured by the CIMS represents only a fraction of the total H2SO4, contained in the monomer and the clusters that is available for particle growth. Although it was found that the addition of dimethylamine dramatically changes the H2SO4 cluster distribution compared to binary (H2SO4-H2O) conditions, the CIMS detection efficiency does not seem to depend substantially on whether an individual H2SO4 monomer is clustered with a DMA molecule. The experimental observations are supported by numerical simulations based on A Self-contained Atmospheric chemistry coDe coupled with a molecular process model (Sulfuric Acid Water NUCleation) operated in the kinetic limit.},
 bibtype = {article},
 author = {Rondo, L. and Ehrhart, S. and Kürten, A. and Adamov, A. and Bianchi, F. and Breitenlechner, M. and Duplissy, J. and Franchin, A. and Dommen, J. and Donahue, N. M. and Dunne, E. M. and Flagan, R. C. and Hakala, J. and Hansel, A. and Keskinen, H. and Kim, J. and Jokinen, T. and Lehtipalo, K. and Leiminger, M. and Praplan, A. and Riccobono, F. and Rissanen, M. P. and Sarnela, N. and Schobesberger, S. and Simon, M. and Sipilä, M. and Smith, J. N. and Tomé, A. and Tröstl, J. and Tsagkogeorgas, G. and Vaattovaara, P. and Winkler, P. M. and Williamson, C. and Wimmer, D. and Baltensperger, U. and Kirkby, J. and Kulmala, M. and Petäjä, T. and Worsnop, D. R. and Curtius, J.},
 doi = {10.1002/2015JD023868},
 journal = {Journal of Geophysical Research},
 number = {6}
}

Sulfuric acid is widely recognized as a very important substance driving atmospheric aerosol nucleation. Based on quantum chemical calculations it has been suggested that the quantitative detection of gas phase sulfuric acid (H2SO4) by use of Chemical Ionization Mass Spectrometry (CIMS) could be biased in the presence of gas phase amines such as dimethylamine (DMA). An experiment (CLOUD7 campaign) was set up at the CLOUD (Cosmics Leaving OUtdoor Droplets) chamber to investigate the quantitative detection of H2SO4 in the presence of dimethylamine by CIMS at atmospherically relevant concentrations. For the first time in the CLOUD experiment, the monomer sulfuric acid concentration was measured by a CIMS and by two CI-APi-TOF (Chemical Ionization-Atmospheric Pressure interface-Time Of Flight) mass spectrometers. In addition, neutral sulfuric acid clusters were measured with the CI-APi-TOFs. The CLOUD7 measurements show that in the presence of dimethylamine (<5 to 70 pptv) the sulfuric acid monomer measured by the CIMS represents only a fraction of the total H2SO4, contained in the monomer and the clusters that is available for particle growth. Although it was found that the addition of dimethylamine dramatically changes the H2SO4 cluster distribution compared to binary (H2SO4-H2O) conditions, the CIMS detection efficiency does not seem to depend substantially on whether an individual H2SO4 monomer is clustered with a DMA molecule. The experimental observations are supported by numerical simulations based on A Self-contained Atmospheric chemistry coDe coupled with a molecular process model (Sulfuric Acid Water NUCleation) operated in the kinetic limit.

@article{
 title = {Rapid cycling of reactive nitrogen in the marine boundary layer},
 type = {article},
 year = {2016},
 pages = {489-491},
 volume = {532},
 websites = {http://www.nature.com/doifinder/10.1038/nature17195},
 id = {c42868b5-f19c-3d2d-b4da-bb3838979255},
 created = {2017-04-12T23:44:41.539Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-08-21T23:00:49.215Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Ye2016},
 source_type = {article},
 notes = {Times Cited: 0 0 1476-4687},
 private_publication = {false},
 abstract = {Nitrogen oxides are essential for the formation of secondary atmospheric aerosols and of atmospheric oxidants such as ozone and the hydroxyl radical, which controls the self-cleansing capacity of the atmosphere. Nitric acid, a major oxidation product of nitrogen oxides, has traditionally been considered to be a permanent sink of nitrogen oxides. However, model studies predict higher ratios of nitric acid to nitrogen oxides in the troposphere than are observed. A "renoxification" process that recycles nitric acid into nitrogen oxides has been proposed to reconcile observations with model studies, but the mechanisms responsible for this process remain uncertain. Here we present data from an aircraft measurement campaign over the North Atlantic Ocean and find evidence for rapid recycling of nitric acid to nitrous acid and nitrogen oxides in the clean marine boundary layer via particulate nitrate photolysis. Laboratory experiments further demonstrate the photolysis of particulate nitrate collected on filters at a rate more than two orders of magnitude greater than that of gaseous nitric acid, with nitrous acid as the main product. Box model calculations based on the Master Chemical Mechanism suggest that particulate nitrate photolysis mainly sustains the observed levels of nitrous acid and nitrogen oxides at midday under typical marine boundary layer conditions. Given that oceans account for more than 70 per cent of Earth's surface, we propose that particulate nitrate photolysis could be a substantial tropospheric nitrogen oxide source. Recycling of nitrogen oxides in remote oceanic regions with minimal direct nitrogen oxide emissions could increase the formation of tropospheric oxidants and secondary atmospheric aerosols on a global scale.},
 bibtype = {article},
 author = {Ye, Chunxiang and Zhou, Xianliang and Pu, Dennis and Stutz, Jochen and Festa, James and Spolaor, Max and Tsai, Catalina and Cantrell, Christopher and Mauldin, Roy L. and Campos, Teresa and Weinheimer, Andrew and Hornbrook, Rebecca S. and Apel, Eric C. and Guenther, Alex and Kaser, Lisa and Yuan, Bin and Karl, Thomas and Haggerty, Julie and Hall, Samuel and Ullmann, Kirk and Smith, James N. and Ortega, John and Knote, Christoph},
 doi = {10.1038/nature17195},
 journal = {Nature},
 number = {7600}
}

Nitrogen oxides are essential for the formation of secondary atmospheric aerosols and of atmospheric oxidants such as ozone and the hydroxyl radical, which controls the self-cleansing capacity of the atmosphere. Nitric acid, a major oxidation product of nitrogen oxides, has traditionally been considered to be a permanent sink of nitrogen oxides. However, model studies predict higher ratios of nitric acid to nitrogen oxides in the troposphere than are observed. A "renoxification" process that recycles nitric acid into nitrogen oxides has been proposed to reconcile observations with model studies, but the mechanisms responsible for this process remain uncertain. Here we present data from an aircraft measurement campaign over the North Atlantic Ocean and find evidence for rapid recycling of nitric acid to nitrous acid and nitrogen oxides in the clean marine boundary layer via particulate nitrate photolysis. Laboratory experiments further demonstrate the photolysis of particulate nitrate collected on filters at a rate more than two orders of magnitude greater than that of gaseous nitric acid, with nitrous acid as the main product. Box model calculations based on the Master Chemical Mechanism suggest that particulate nitrate photolysis mainly sustains the observed levels of nitrous acid and nitrogen oxides at midday under typical marine boundary layer conditions. Given that oceans account for more than 70 per cent of Earth's surface, we propose that particulate nitrate photolysis could be a substantial tropospheric nitrogen oxide source. Recycling of nitrogen oxides in remote oceanic regions with minimal direct nitrogen oxide emissions could increase the formation of tropospheric oxidants and secondary atmospheric aerosols on a global scale.

@article{
 title = {Hygroscopicity of nanoparticles produced from homogeneous nucleation in the CLOUD experiments},
 type = {article},
 year = {2016},
 pages = {293-304},
 volume = {16},
 id = {679c94f5-bddd-3b76-a04a-bc16296abe4c},
 created = {2018-11-21T20:51:12.103Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-11-02T20:28:37.134Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Kim2016},
 source_type = {JOUR},
 notes = {Times Cited: 0<br/>Petaja, Tuukka/A-8009-2008; Bianchi, Federico/G-8428-2012; Kirkby, Jasper/A-4973-2012; Tome, Antonio/A-5681-2013<br/>Petaja, Tuukka/0000-0002-1881-9044; Bianchi, Federico/0000-0003-2996-3604; Kirkby, Jasper/0000-0003-2341-9069; Tome, Antonio/0000-0001-9144-7120<br/>0<br/>1680-7324},
 private_publication = {false},
 abstract = {Sulfuric acid, amines and oxidized organics have been found to be important compounds in the nucleation and initial growth of atmospheric particles. Because of the challenges involved in determining the chemical composition of objects with very small mass, however, the properties of the freshly nucleated particles and the detailed pathways of their formation processes are still not clear. In this study, we focus on a challenging size range, i.e., particles that have grown to diameters of 10 and 15gnm following nucleation, and measure their water uptake. Water uptake is useful information for indirectly obtaining chemical composition of aerosol particles. We use a nanometer-hygroscopicity tandem differential mobility analyzer (nano-HTDMA) at subsaturated conditions (ca. 90g% relative humidity at 293gK) to measure the hygroscopicity of particles during the seventh Cosmics Leaving OUtdoor Droplets (CLOUD7) campaign performed at CERN in 2012. In CLOUD7, the hygroscopicity of nucleated nanoparticles was measured in the presence of sulfuric acid, sulfuric acid-dimethylamine, and sulfuric acid-organics derived from α-pinene oxidation. The hygroscopicity parameter decreased with increasing particle size, indicating decreasing acidity of particles. No clear effect of the sulfuric acid concentration on the hygroscopicity of 10gnm particles produced from sulfuric acid and dimethylamine was observed, whereas the hygroscopicity of 15gnm particles sharply decreased with decreasing sulfuric acid concentrations. In particular, when the concentration of sulfuric acid was 5.1 × 106gmoleculesgcmg'3 in the gas phase, and the dimethylamine mixing ratio was 11.8gppt, the measured of 15gnm particles was 0.31g±g0.01: close to the value reported for dimethylaminium sulfate (DMAS) (DMAS g1/4 0.28). Furthermore, the difference in between sulfuric acid and sulfuric acid-imethylamine experiments increased with increasing particle size. The values of particles in the presence of sulfuric acid and organics were much smaller than those of particles in the presence of sulfuric acid and dimethylamine. This suggests that the organics produced from α-pinene ozonolysis play a significant role in particle growth even at 10gnm sizes.},
 bibtype = {article},
 author = {Kim, J. and Ahlm, L. and Yli-Juuti, T. and Lawler, M. and Keskinen, H. and Tröstl, J. and Schobesberger, S. and Duplissy, J. and Amorim, A. and Bianchi, F. and Donahue, N. M. and Flagan, R. C. and Hakala, J. and Heinritzi, M. and Jokinen, T. and Kürten, A. and Laaksonen, A. and Lehtipalo, K. and Miettinen, P. and Petäjä, T. and Rissanen, M. P. and Rondo, L. and Sengupta, K. and Simon, M. and Tomé, A. and Williamson, C. and Wimmer, D. and Winkler, P. M. and Ehrhart, S. and Ye, P. and Kirkby, J. and Curtius, J. and Baltensperger, U. and Kulmala, M. and Lehtinen, K. E.J. and Smith, J. N. and Riipinen, I. and Virtanen, A.},
 doi = {10.5194/acp-16-293-2016},
 journal = {Atmospheric Chemistry and Physics},
 number = {1}
}

Sulfuric acid, amines and oxidized organics have been found to be important compounds in the nucleation and initial growth of atmospheric particles. Because of the challenges involved in determining the chemical composition of objects with very small mass, however, the properties of the freshly nucleated particles and the detailed pathways of their formation processes are still not clear. In this study, we focus on a challenging size range, i.e., particles that have grown to diameters of 10 and 15gnm following nucleation, and measure their water uptake. Water uptake is useful information for indirectly obtaining chemical composition of aerosol particles. We use a nanometer-hygroscopicity tandem differential mobility analyzer (nano-HTDMA) at subsaturated conditions (ca. 90g% relative humidity at 293gK) to measure the hygroscopicity of particles during the seventh Cosmics Leaving OUtdoor Droplets (CLOUD7) campaign performed at CERN in 2012. In CLOUD7, the hygroscopicity of nucleated nanoparticles was measured in the presence of sulfuric acid, sulfuric acid-dimethylamine, and sulfuric acid-organics derived from α-pinene oxidation. The hygroscopicity parameter decreased with increasing particle size, indicating decreasing acidity of particles. No clear effect of the sulfuric acid concentration on the hygroscopicity of 10gnm particles produced from sulfuric acid and dimethylamine was observed, whereas the hygroscopicity of 15gnm particles sharply decreased with decreasing sulfuric acid concentrations. In particular, when the concentration of sulfuric acid was 5.1 × 106gmoleculesgcmg'3 in the gas phase, and the dimethylamine mixing ratio was 11.8gppt, the measured of 15gnm particles was 0.31g±g0.01: close to the value reported for dimethylaminium sulfate (DMAS) (DMAS g1/4 0.28). Furthermore, the difference in between sulfuric acid and sulfuric acid-imethylamine experiments increased with increasing particle size. The values of particles in the presence of sulfuric acid and organics were much smaller than those of particles in the presence of sulfuric acid and dimethylamine. This suggests that the organics produced from α-pinene ozonolysis play a significant role in particle growth even at 10gnm sizes.

@article{
 title = {Experimental particle formation rates spanning tropospheric sulfuric acid and ammonia abundances, ion production rates, and temperatures},
 type = {article},
 year = {2016},
 pages = {12,377-12,400},
 volume = {121},
 websites = {http://onlinelibrary.wiley.com/doi/10.1002/2015JD023908/full},
 id = {21b5ee74-6242-35d8-8967-05d047def3ce},
 created = {2023-01-31T22:46:09.971Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:09.971Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Kurten2016},
 source_type = {article},
 private_publication = {false},
 abstract = {Binary nucleation of sulfuric acid and water as well as ternary nucleation involving ammonia are thought to be the dominant processes responsible for new particle formation (NPF) in the cold temperatures of the middle and upper troposphere. Ions are also thought to be important for particle nucleation in these regions. However, global models presently lack experimentally measured NPF rates under controlled laboratory conditions and so at present must rely on theoretical or empirical parameterizations. Here with data obtained in the European Organization for Nuclear Research CLOUD (Cosmics Leaving OUtdoor Droplets) chamber, we present the first experimental survey of NPF rates spanning free tropospheric conditions. The conditions during nucleation cover a temperature range from 208 to 298 K, sulfuric acid concentrations between 5 × 105 and 1 × 109cm-3, and ammonia mixing ratios from zero added ammonia, i.e., nominally pure binary, to a maximumof ~1400 parts per trillion by volume (pptv).We performed nucleation studies under pure neutral conditions with zero ions being present in the chamber and at ionization rates of up to 75 ion pairs cm-3 s-1 to study neutral and ion-induced nucleation. We found that the contribution from ion-induced nucleation is small at temperatures between 208 and 248 K when ammonia is present at several pptv or higher. However, the presence of charges significantly enhances the nucleation rates, especially at 248 K with zero added ammonia, and for higher temperatures independent of NH3 levels.We compare these experimental data with calculated cluster formation rates from the Atmospheric Cluster Dynamics Code with cluster evaporation rates obtained from quantum chemistry.},
 bibtype = {article},
 author = {Kuerten, Andreas and Bianchi, Federico and Almeida, Joao and Kupiainen-Maatta, Oona and Dunne, Eimear M. and Duplissy, Jonathan and Williamson, Christina and Barmet, Peter and Breitenlechner, Martin and Dommen, Josef and Donahue, Neil M. and Flagan, Richard C. and Franchin, Alessandro and Gordon, Hamish and Hakala, Jani and Hansel, Armin and Heinritzi, Martin and Ickes, Luisa and Jokinen, Tuija and Kangasluoma, Juha and Kim, Jaeseok and Kirkby, Jasper and Kupc, Agnieszka and Lehtipalo, Katrianne and Leiminger, Markus and Makhmutov, Vladimir and Onnela, Antti and Ortega, Ismael K. and Petaja, Tuukka and Praplan, Arnaud P. and Riccobono, Francesco and Rissanen, Matti P. and Rondo, Linda and Schnitzhofer, Ralf and Schobesberger, Siegfried and Smith, James N. and Steiner, Gerhard and Stozhkov, Yuri and Tome, Antonio and Trostl, Jasmin and Tsagkogeorgas, Georgios and Wagner, Paul E. and Wimmer, Daniela and Ye, Penglin and Baltensperger, Urs and Carslaw, Ken and Kulmala, Markku and Curtius, Joachim and Kürten, Andreas and Bianchi, Federico and Almeida, Joao and Kupiainen-Määttä, Oona and Dunne, Eimear M. and Duplissy, Jonathan and Williamson, Christina and Barmet, Peter and Breitenlechner, Martin and Dommen, Josef and Donahue, Neil M. and Flagan, Richard C. and Franchin, Alessandro and Gordon, Hamish and Hakala, Jani and Hansel, Armin and Heinritzi, Martin and Ickes, Luisa and Jokinen, Tuija and Kangasluoma, Juha and Kim, Jaeseok and Kirkby, Jasper and Kupc, Agnieszka and Lehtipalo, Katrianne and Leiminger, Markus and Makhmutov, Vladimir and Onnela, Antti and Ortega, Ismael K. and Petäjä, Tuukka and Praplan, Arnaud P. and Riccobono, Francesco and Rissanen, Matti P. and Rondo, Linda and Schnitzhofer, Ralf and Schobesberger, Siegfried and Smith, James N. and Steiner, Gerhard and Stozhkov, Yuri and Tomé, António and Tröstl, Jasmin and Tsagkogeorgas, Georgios and Wagner, Paul E. and Wimmer, Daniela and Ye, Penglin and Baltensperger, Urs and Carslaw, Ken and Kulmala, Markku and Curtius, Joachim},
 doi = {10.1002/2015JD023908},
 journal = {Journal of Geophysical Research},
 number = {20}
}

Binary nucleation of sulfuric acid and water as well as ternary nucleation involving ammonia are thought to be the dominant processes responsible for new particle formation (NPF) in the cold temperatures of the middle and upper troposphere. Ions are also thought to be important for particle nucleation in these regions. However, global models presently lack experimentally measured NPF rates under controlled laboratory conditions and so at present must rely on theoretical or empirical parameterizations. Here with data obtained in the European Organization for Nuclear Research CLOUD (Cosmics Leaving OUtdoor Droplets) chamber, we present the first experimental survey of NPF rates spanning free tropospheric conditions. The conditions during nucleation cover a temperature range from 208 to 298 K, sulfuric acid concentrations between 5 × 105 and 1 × 109cm-3, and ammonia mixing ratios from zero added ammonia, i.e., nominally pure binary, to a maximumof ~1400 parts per trillion by volume (pptv).We performed nucleation studies under pure neutral conditions with zero ions being present in the chamber and at ionization rates of up to 75 ion pairs cm-3 s-1 to study neutral and ion-induced nucleation. We found that the contribution from ion-induced nucleation is small at temperatures between 208 and 248 K when ammonia is present at several pptv or higher. However, the presence of charges significantly enhances the nucleation rates, especially at 248 K with zero added ammonia, and for higher temperatures independent of NH3 levels.We compare these experimental data with calculated cluster formation rates from the Atmospheric Cluster Dynamics Code with cluster evaporation rates obtained from quantum chemistry.

@article{
 title = {The role of low-volatility organic compounds in initial particle growth in the atmosphere},
 type = {article},
 year = {2016},
 pages = {527-531},
 volume = {533},
 websites = {http://www.nature.com/doifinder/10.1038/nature18271},
 id = {2c499a53-7875-399b-bb95-d4bc44ccfcae},
 created = {2023-01-31T22:46:10.098Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:10.098Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Trostl2016a},
 source_type = {JOUR},
 private_publication = {false},
 abstract = {About half of present-day cloud condensation nuclei originate from atmospheric nucleation, frequently appearing as a burst of new particles near midday1. Atmospheric observations show that the growth rate of new particles often accelerates when the diameter of the particles is between one and ten nanometres2,3. In this critical size range, new particles are most likely to be lost by coagulation with pre-existing particles4, thereby failing to form new cloud condensation nuclei that are typically 50 to 100 nanometres across. Sulfuric acid vapour is often involved in nucleation but is too scarce to explain most subsequent growth5,6, leaving organic vapours as the most plausible alternative, at least in the planetary boundary layer7-10. Although recent studies11-13 predict that low-volatility organic vapours contribute during initial growth, direct evidence has been lacking. The accelerating growth may result from increased photolytic production of condensable organic species in the afternoon2, and the presence of a possible Kelvin (curvature) effect, which inhibits organic vapour condensation on the smallest particles (the nano-Köhler theory)2,14, has so far remained ambiguous. Here we present experiments performed in a large chamber under atmospheric conditions that investigate the role of organic vapours in the initial growth of nucleated organic particles in the absence of inorganic acids and bases such as sulfuric acid or ammonia and amines, respectively. Using data from the same set of experiments, it has been shown15 that organic vapours alone can drive nucleation. We focus on the growth of nucleated particles and find that the organic vapours that drive initial growth have extremely low volatilities (saturation concentration less than 10-4.5 micrograms per cubic metre). As the particles increase in size and the Kelvin barrier falls, subsequent growth is primarily due to more abundant organic vapours of slightly higher volatility (saturation concentrations of 10-4.5 to 10-0.5 micrograms per cubic metre). We present a particle growth model that quantitatively reproduces our measurements. Furthermore, we implement a parameterization of the first steps of growth in a global aerosol model and find that concentrations of atmospheric cloud concentration nuclei can change substantially in response, that is, by up to 50 per cent in comparison with previously assumed growth rate parameterizations.},
 bibtype = {article},
 author = {Tröstl, Jasmin and Chuang, Wayne K. and Gordon, Hamish and Heinritzi, Martin and Yan, Chao and Molteni, Ugo and Ahlm, Lars and Frege, Carla and Bianchi, Federico and Wagner, Robert and Simon, Mario and Lehtipalo, Katrianne and Williamson, Christina and Craven, Jill S. and Duplissy, Jonathan and Adamov, Alexey and Almeida, Joao and Bernhammer, Anne-Kathrin Kathrin and Breitenlechner, Martin and Brilke, Sophia and Dias, Antònio Antonio and Ehrhart, Sebastian and Flagan, Richard C. and Franchin, Alessandro and Fuchs, Claudia and Guida, Roberto and Gysel, Martin and Hansel, Armin and Hoyle, Christopher R. and Jokinen, Tuija and Junninen, Heikki and Kangasluoma, Juha and Keskinen, Helmi and Kim, Jaeseok and Krapf, Manuel and Kürten, Andreas and Laaksonen, Ari and Lawler, Michael and Leiminger, Markus and Mathot, Serge and Möhler, Ottmar and Nieminen, Tuomo and Onnela, Antti and Petäjä, Tuukka and Piel, Felix M. and Miettinen, Pasi and Rissanen, Matti P. and Rondo, Linda and Sarnela, Nina and Schobesberger, Siegfried and Sengupta, Kamalika and Sipilä, Mikko and Smith, James N. and Steiner, Gerhard and Tomè, Antònio and Virtanen, Annele and Wagner, Andrea C. and Weingartner, Ernest and Wimmer, Daniela and Winkler, Paul M. and Ye, Penglin and Carslaw, Kenneth S. and Curtius, Joachim and Dommen, Josef and Kirkby, Jasper and Kulmala, Markku and Riipinen, Ilona and Worsnop, Douglas R. and Donahue, Neil M. and Baltensperger, Urs and Troestl, Jasmin and Chuang, Wayne K. and Gordon, Hamish and Heinritzi, Martin and Yan, Chao and Molteni, Ugo and Ahlm, Lars and Frege, Carla and Bianchi, Federico and Wagner, Robert and Simon, Mario and Lehtipalo, Katrianne and Williamson, Christina and Craven, Jill S. and Duplissy, Jonathan and Adamov, Alexey and Almeida, Joao and Bernhammer, Anne-Kathrin Kathrin and Breitenlechner, Martin and Brilke, Sophia and Dias, Antònio Antonio and Ehrhart, Sebastian and Flagan, Richard C. and Franchin, Alessandro and Fuchs, Claudia and Guida, Roberto and Gysel, Martin and Hansel, Armin and Hoyle, Christopher R. and Jokinen, Tuija and Junninen, Heikki and Kangasluoma, Juha and Keskinen, Helmi and Kim, Jaeseok and Krapf, Manuel and Kuerten, Andreas and Laaksonen, Ari and Lawler, Michael and Leiminger, Markus and Mathot, Serge and Moehler, Ottmar and Nieminen, Tuomo and Onnela, Antti and Petaejae, Tuukka and Piel, Felix M. and Miettinen, Pasi and Rissanen, Matti P. and Rondo, Linda and Sarnela, Nina and Schobesberger, Siegfried and Sengupta, Kamalika and Sipilae, Mikko and Smith, James N. and Steiner, Gerhard and Tome, Antonio and Virtanen, Annele and Wagner, Andrea C. and Weingartner, Ernest and Wimmer, Daniela and Winkler, Paul M. and Ye, Penglin and Carslaw, Kenneth S. and Curtius, Joachim and Dommen, Josef and Kirkby, Jasper and Kulmala, Markku and Riipinen, Ilona and Worsnop, Douglas R. and Donahue, Neil M. and Baltensperger, Urs},
 doi = {10.1038/nature18271},
 journal = {Nature},
 number = {7604}
}

About half of present-day cloud condensation nuclei originate from atmospheric nucleation, frequently appearing as a burst of new particles near midday1. Atmospheric observations show that the growth rate of new particles often accelerates when the diameter of the particles is between one and ten nanometres2,3. In this critical size range, new particles are most likely to be lost by coagulation with pre-existing particles4, thereby failing to form new cloud condensation nuclei that are typically 50 to 100 nanometres across. Sulfuric acid vapour is often involved in nucleation but is too scarce to explain most subsequent growth5,6, leaving organic vapours as the most plausible alternative, at least in the planetary boundary layer7-10. Although recent studies11-13 predict that low-volatility organic vapours contribute during initial growth, direct evidence has been lacking. The accelerating growth may result from increased photolytic production of condensable organic species in the afternoon2, and the presence of a possible Kelvin (curvature) effect, which inhibits organic vapour condensation on the smallest particles (the nano-Köhler theory)2,14, has so far remained ambiguous. Here we present experiments performed in a large chamber under atmospheric conditions that investigate the role of organic vapours in the initial growth of nucleated organic particles in the absence of inorganic acids and bases such as sulfuric acid or ammonia and amines, respectively. Using data from the same set of experiments, it has been shown15 that organic vapours alone can drive nucleation. We focus on the growth of nucleated particles and find that the organic vapours that drive initial growth have extremely low volatilities (saturation concentration less than 10-4.5 micrograms per cubic metre). As the particles increase in size and the Kelvin barrier falls, subsequent growth is primarily due to more abundant organic vapours of slightly higher volatility (saturation concentrations of 10-4.5 to 10-0.5 micrograms per cubic metre). We present a particle growth model that quantitatively reproduces our measurements. Furthermore, we implement a parameterization of the first steps of growth in a global aerosol model and find that concentrations of atmospheric cloud concentration nuclei can change substantially in response, that is, by up to 50 per cent in comparison with previously assumed growth rate parameterizations.

@article{
 title = {Unexpectedly acidic nanoparticles formed in dimethylamine-ammonia-sulfuric-acid nucleation experiments at CLOUD},
 type = {article},
 year = {2016},
 pages = {13601-13618},
 volume = {16},
 websites = {http://www.atmos-chem-phys.net/16/13601/2016/},
 month = {11},
 day = {3},
 id = {c1f0f931-2b57-3843-af04-2df047b251ae},
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 last_modified = {2023-01-31T22:46:35.757Z},
 read = {false},
 starred = {false},
 authored = {true},
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 hidden = {false},
 citation_key = {Lawler2016},
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 folder_uuids = {166824d9-9061-4c8b-bfd7-92a782f92781,e9db4589-c14d-471c-8b7a-bb4b8e16be27},
 private_publication = {false},
 abstract = {New particle formation driven by acid-base chemistry was initiated in the CLOUD chamber at CERN by introducing atmospherically relevant levels of gas-phase sulfuric acid and dimethylamine (DMA). Ammonia was also present in the chamber as a gas-phase contaminant from earlier experiments. The composition of particles with volume median diameters (VMDs) as small as 10ĝ€nm was measured by the Thermal Desorption Chemical Ionization Mass Spectrometer (TDCIMS). Particulate ammonium-to-dimethylaminium ratios were higher than the gas-phase ammonia-to-DMA ratios, suggesting preferential uptake of ammonia over DMA for the collected 10-30ĝ€nm VMD particles. This behavior is not consistent with present nanoparticle physicochemical models, which predict a higher dimethylaminium fraction when NH3 and DMA are present at similar gas-phase concentrations. Despite the presence in the gas phase of at least 100 times higher base concentrations than sulfuric acid, the recently formed particles always had measured baseĝ€:ĝ€acid ratios lower than 1ĝ€:ĝ€1. The lowest base fractions were found in particles below 15ĝ€nm VMD, with a strong size-dependent composition gradient. The reasons for the very acidic composition remain uncertain, but a plausible explanation is that the particles did not reach thermodynamic equilibrium with respect to the bases due to rapid heterogeneous conversion of SO2 to sulfate. These results indicate that sulfuric acid does not require stabilization by ammonium or dimethylaminium as acid-base pairs in particles as small as 10ĝ€nm.},
 bibtype = {article},
 author = {Lawler, Michael J. and Winkler, Paul M. and Kim, Jaeseok and Ahlm, Lars and Tröstl, Jasmin and Praplan, Arnaud P. and Schobesberger, Siegfried and Kürten, Andreas and Kirkby, Jasper and Bianchi, Federico and Duplissy, Jonathan and Hansel, Armin and Jokinen, Tuija and Keskinen, Helmi and Lehtipalo, Katrianne and Leiminger, Markus and Petäjä, Tuukka and Rissanen, Matti and Rondo, Linda and Simon, Mario and Sipilä, Mikko and Williamson, Christina and Wimmer, Daniela and Riipinen, Ilona and Virtanen, Annele and Smith, James N.},
 doi = {10.5194/acp-16-13601-2016},
 journal = {Atmospheric Chemistry and Physics},
 number = {21}
}

New particle formation driven by acid-base chemistry was initiated in the CLOUD chamber at CERN by introducing atmospherically relevant levels of gas-phase sulfuric acid and dimethylamine (DMA). Ammonia was also present in the chamber as a gas-phase contaminant from earlier experiments. The composition of particles with volume median diameters (VMDs) as small as 10ĝ€nm was measured by the Thermal Desorption Chemical Ionization Mass Spectrometer (TDCIMS). Particulate ammonium-to-dimethylaminium ratios were higher than the gas-phase ammonia-to-DMA ratios, suggesting preferential uptake of ammonia over DMA for the collected 10-30ĝ€nm VMD particles. This behavior is not consistent with present nanoparticle physicochemical models, which predict a higher dimethylaminium fraction when NH3 and DMA are present at similar gas-phase concentrations. Despite the presence in the gas phase of at least 100 times higher base concentrations than sulfuric acid, the recently formed particles always had measured baseĝ€:ĝ€acid ratios lower than 1ĝ€:ĝ€1. The lowest base fractions were found in particles below 15ĝ€nm VMD, with a strong size-dependent composition gradient. The reasons for the very acidic composition remain uncertain, but a plausible explanation is that the particles did not reach thermodynamic equilibrium with respect to the bases due to rapid heterogeneous conversion of SO2 to sulfate. These results indicate that sulfuric acid does not require stabilization by ammonium or dimethylaminium as acid-base pairs in particles as small as 10ĝ€nm.

@article{
 title = {A field campaign to elucidate the impact of biogenic aerosols on clouds and climate},
 type = {article},
 year = {2016},
 pages = {1909-1928},
 volume = {97},
 websites = {http://journals.ametsoc.org/doi/10.1175/BAMS-D-14-00199.1},
 month = {10},
 id = {531ab859-69e9-33f7-ae3a-db36adf6c788},
 created = {2023-01-31T22:46:14.110Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:36.310Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {ISI:000389208100011},
 source_type = {article},
 folder_uuids = {e9db4589-c14d-471c-8b7a-bb4b8e16be27,d013c061-b5b7-4df2-8907-4cdb256c465f},
 private_publication = {false},
 abstract = {Observations obtained during an 8-month deployment of AMF2 in a boreal environment in Hyytiälä, Finland, and comprehensive in situ data from the SMEAR II station enable the characterization of biogenic aerosol, clouds, and precipitation and their interactions.},
 bibtype = {article},
 author = {Petäjä, Tuukka and O'Connor, Ewan J. and Moisseev, Dmitri and Sinclair, Victoria A. and Manninen, Antti J. and Väänänen, Riikka and Von Lerber, Annakaisa and Thornton, Joel A. and Nicoll, Keri and Petersen, Walt and Chandrasekar, V. and Smith, James N. and Winkler, Paul M. and KrüGer, Olaf and Hakola, Hannele and Timonen, Hilkka and Brus, David and Laurila, Tuomas and Asmi, Eija and Riekkola, Marja Liisa and Mona, Lucia and Massoli, Paola and Engelmann, Ronny and Komppula, Mika and Wang, Jian and Kuang, Chongai and BäCk, Jaana and Virtanen, Annele and Levula, Janne and Ritsche, Michael and Hickmon, Nicki},
 doi = {10.1175/BAMS-D-14-00199.1},
 journal = {Bulletin of the American Meteorological Society},
 number = {10}
}

Observations obtained during an 8-month deployment of AMF2 in a boreal environment in Hyytiälä, Finland, and comprehensive in situ data from the SMEAR II station enable the characterization of biogenic aerosol, clouds, and precipitation and their interactions.

@article{
 title = {Spring and summer contrast in new particle formation over nine forest areas in North America},
 type = {article},
 year = {2015},
 pages = {13993-14003},
 volume = {15},
 websites = {http://www.atmos-chem-phys.net/15/13993/2015/},
 month = {12},
 day = {18},
 id = {0f2328e7-c724-3ce4-ba56-869ffc26f8d3},
 created = {2017-04-12T23:44:41.947Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-11-02T20:28:34.297Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Yu2015},
 source_type = {article},
 notes = {Times Cited: 0 Yu, Fangqun/F-3708-2011; Hallar, Anna Gannet/I-9104-2012; Pryor, S.C./ Yu, Fangqun/0000-0003-0874-4883; Hallar, Anna Gannet/0000-0001-9972-0056; Pryor, S.C./0000-0003-4847-3440 0 1680-7324},
 private_publication = {false},
 abstract = {Recent laboratory chamber studies indicate a significant role for highly oxidized low-volatility organics in new particle formation (NPF), but the actual role of these highly oxidized low-volatility organics in atmospheric NPF remains uncertain. Here, particle size distributions (PSDs) measured in nine forest areas in North America are used to characterize the occurrence and intensity of NPF and to evaluate model simulations using an empirical formulation in which formation rate is a function of the concentrations of sulfuric acid and low-volatility organics from alpha-pinene oxidation (Nucl-Org), and using an ion-mediated nucleation mechanism (excluding organics) (Nucl-IMN). On average, NPF occurred on ∼ 70 % of days during March for the four forest sites with springtime PSD measurements, while NPF occurred on only ∼ 10 % of days in July for all nine forest sites. Both Nucl-Org and Nucl-IMN schemes capture the observed high frequency of NPF in spring, but the Nucl-Org scheme significantly overpredicts while the Nucl-IMN scheme slightly underpredicts NPF and particle number concentrations in summer. Statistical analyses of observed and simulated ultrafine particle number concentrations and frequency of NPF events indicate that the scheme without organics agrees better overall with observations. The two schemes predict quite different nucleation rates (including their spatial patterns), concentrations of cloud condensation nuclei, and aerosol first indirect radiative forcing in North America, highlighting the need to reduce NPF uncertainties in regional and global earth system models.},
 bibtype = {article},
 author = {Yu, F. and Luo, G. and Pryor, S. C. and Pillai, P. R. and Lee, S. H. and Ortega, J. and Schwab, J. J. and Hallar, A. G. and Leaitch, W. R. and Aneja, V. P. and Smith, J. N. and Walker, J. T. and Hogrefe, O. and Demerjian, K. L.},
 doi = {10.5194/acp-15-13993-2015},
 journal = {Atmospheric Chemistry and Physics},
 number = {24}
}

Recent laboratory chamber studies indicate a significant role for highly oxidized low-volatility organics in new particle formation (NPF), but the actual role of these highly oxidized low-volatility organics in atmospheric NPF remains uncertain. Here, particle size distributions (PSDs) measured in nine forest areas in North America are used to characterize the occurrence and intensity of NPF and to evaluate model simulations using an empirical formulation in which formation rate is a function of the concentrations of sulfuric acid and low-volatility organics from alpha-pinene oxidation (Nucl-Org), and using an ion-mediated nucleation mechanism (excluding organics) (Nucl-IMN). On average, NPF occurred on ∼ 70 % of days during March for the four forest sites with springtime PSD measurements, while NPF occurred on only ∼ 10 % of days in July for all nine forest sites. Both Nucl-Org and Nucl-IMN schemes capture the observed high frequency of NPF in spring, but the Nucl-Org scheme significantly overpredicts while the Nucl-IMN scheme slightly underpredicts NPF and particle number concentrations in summer. Statistical analyses of observed and simulated ultrafine particle number concentrations and frequency of NPF events indicate that the scheme without organics agrees better overall with observations. The two schemes predict quite different nucleation rates (including their spatial patterns), concentrations of cloud condensation nuclei, and aerosol first indirect radiative forcing in North America, highlighting the need to reduce NPF uncertainties in regional and global earth system models.

@article{
 title = {Contribution from biogenic organic compounds to particle growth during the 2010 BEACHON-ROCS campaign in a Colorado temperate needleleaf forest},
 type = {article},
 year = {2015},
 pages = {8643-8656},
 volume = {15},
 websites = {http://www.atmos-chem-phys.net/15/8643/2015/},
 month = {8},
 day = {6},
 id = {08b20602-4693-3bdf-9dc6-68976d827f04},
 created = {2017-04-12T23:44:42.215Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-11-02T20:28:33.983Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Zhou2015},
 source_type = {article},
 notes = {Times Cited: 0 Levin, Ezra/F-5809-2010; Boy, Michael/C-2920-2015; Karl, Thomas/D-1891-2009 Boy, Michael/0000-0002-8107-4524; Karl, Thomas/0000-0003-2869-9426 0 1680-7324},
 private_publication = {false},
 abstract = {New particle formation (NPF) is an important atmospheric phenomenon. During an NPF event, particles first form by nucleation and then grow further in size. The growth step is crucial because it controls the number of particles that can become cloud condensation nuclei. Among various physical and chemical processes contributing to particle growth, condensation by organic vapors has been suggested as important. In order to better understand the influence of biogenic emissions on particle growth, we carried out modeling studies of NPF events during the BEACHON-ROCS (Bio-hydro-atmosphere interactions of Energy, Aerosol, Carbon, H2O, Organics & Nitrogen - Rocky Mountain Organic Carbon Study) campaign at Manitou Experimental Forest Observatory in Colorado, USA. The site is representative of the semi-arid western USA. With the latest Criegee intermediate reaction rates implemented in the chemistry scheme, the model underestimates sulfuric acid concentration by 50 %, suggesting either missing sources of atmospheric sulfuric acid or an overestimated sink term. The results emphasize the contribution from biogenic volatile organic compound emissions to particle growth by demonstrating the effects of the oxidation products of monoterpenes and 2-Methyl-3-buten-2-ol (MBO). Monoterpene oxidation products are shown to influence the nighttime particle loadings significantly, while their concentrations are insufficient to grow the particles during the day. The growth of ultrafine particles in the daytime appears to be closely related to the OH oxidation products of MBO.},
 bibtype = {article},
 author = {Zhou, L. and Gierens, R. and Sogachev, A. and Mogensen, D. and Ortega, J. and Smith, J. N. and Harley, P. C. and Prenni, A. J. and Levin, E. J.T. and Turnipseed, A. and Rusanen, A. and Smolander, S. and Guenther, A. B. and Kulmala, M. and Karl, T. and Boy, M.},
 doi = {10.5194/acp-15-8643-2015},
 journal = {Atmospheric Chemistry and Physics},
 number = {15}
}

New particle formation (NPF) is an important atmospheric phenomenon. During an NPF event, particles first form by nucleation and then grow further in size. The growth step is crucial because it controls the number of particles that can become cloud condensation nuclei. Among various physical and chemical processes contributing to particle growth, condensation by organic vapors has been suggested as important. In order to better understand the influence of biogenic emissions on particle growth, we carried out modeling studies of NPF events during the BEACHON-ROCS (Bio-hydro-atmosphere interactions of Energy, Aerosol, Carbon, H2O, Organics & Nitrogen - Rocky Mountain Organic Carbon Study) campaign at Manitou Experimental Forest Observatory in Colorado, USA. The site is representative of the semi-arid western USA. With the latest Criegee intermediate reaction rates implemented in the chemistry scheme, the model underestimates sulfuric acid concentration by 50 %, suggesting either missing sources of atmospheric sulfuric acid or an overestimated sink term. The results emphasize the contribution from biogenic volatile organic compound emissions to particle growth by demonstrating the effects of the oxidation products of monoterpenes and 2-Methyl-3-buten-2-ol (MBO). Monoterpene oxidation products are shown to influence the nighttime particle loadings significantly, while their concentrations are insufficient to grow the particles during the day. The growth of ultrafine particles in the daytime appears to be closely related to the OH oxidation products of MBO.

@article{
 title = {Real-time chemical composition analysis of particulate emissions from woodchip combustion},
 type = {article},
 year = {2015},
 keywords = {aerosol,aerosol mass-spectrometer positive matrix factoriz,aki-matti,and it was in,chemical composition,combustion,fi,for example c 6,h 5,in incomplete,kortelainen,presenting author email,species,the background,throughout the combustion experiment,uef},
 pages = {1143-1150},
 volume = {29},
 websites = {http://pubs.acs.org/doi/abs/10.1021/ef5019548},
 city = {[Kortelainen, Aki; Joutsensaari, Jorma; Hao, Liqing; Jaatinen, Antti; Miettinen, Pasi; Worsnop, Douglas R.; Smith, James N.; Laaksonen, Ari; Virtanen, Annele] Univ Eastern Finland, Dept Appl Phys, Kuopio 70211, Finland. [Leskinen, Jani; Tiitta, Petri; Sip},
 id = {1f53dfed-e3f7-306a-a374-b53e8d1aeee7},
 created = {2023-01-31T22:46:05.649Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:05.649Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Kortelainen2015},
 source_type = {article},
 language = {English},
 notes = {<b>From Duplicate 1 (<i>Real-time chemical composition analysis of particulate emissions from woodchip combustion</i> - Kortelainen, Aki; Joutsensaari, Jorma; Hao, Liqing; Leskinen, Jani; Tiitta, Petri; Jaatinen, Antti; Miettinen, Pasi; Sippula, Olli; Torvela, Tiina; Tissari, Jarkko; Jokiniemi, Jorma; Worsnop, Douglas R.; Smith, James N.; Laaksonen, Ari; Virtanen, Annele)<br/></b><br/><b>From Duplicate 1 (<i>Real-time chemical composition analysis of particulate emissions from woodchip combustion</i> - Kortelainen, Aki; Joutsensaari, Jorma; Hao, Liqing; Leskinen, Jani; Tiitta, Petri; Jaatinen, Antti; Miettinen, Pasi; Sippula, Olli; Torvela, Tiina; Tissari, Jarkko; Jokiniemi, Jorma; Worsnop, Douglas R.; Smith, James N.; Laaksonen, Ari; Virtanen, Annele)<br/></b><br/>ISI Document Delivery No.: CB9HT<br/>Times Cited: 4<br/>Cited Reference Count: 39<br/>Kortelainen, Aki Joutsensaari, Jorma Hao, Liqing Leskinen, Jani Tiitta, Petri Jaatinen, Antti Miettinen, Pasi Sippula, Olli Torvela, Tiina Tissari, Jarkko Jokiniemi, Jorma Worsnop, Douglas R. Smith, James N. Laaksonen, Ari Virtanen, Annele<br/>Academy of Finland Centre of Excellence Program [1118615]; ERA-NET Bioenergy BioHealth Project [40392/09, dnro 1262/31/09]; UEF Postdoc Research Foundation [930275]<br/>The financial support by the Academy of Finland Centre of Excellence Program (Project 1118615) and the ERA-NET Bioenergy BioHealth Project (Grant Agreement 40392/09, dnro 1262/31/09) is gratefully acknowledged. Liqing Hao acknowledges the financial support of the UEF Postdoc Research Foundation (930275).<br/>Amer chemical soc<br/>Washington<br/><br/><b>From Duplicate 2 (<i>Real-time chemical composition analysis of particulate emissions from woodchip combustion</i> - Kortelainen, Aki; Joutsensaari, Jorma; Hao, Liqing; Leskinen, Jani; Tiitta, Petri; Jaatinen, Antti; Miettinen, Pasi; Sippula, Olli; Torvela, Tiina; Tissari, Jarkko; Jokiniemi, Jorma; Worsnop, Douglas R.; Smith, James N.; Laaksonen, Ari; Virtanen, Annele)<br/></b><br/>Times Cited: 0 Virtanen, Annele/E-7699-2010; Laaksonen, Ari/B-5094-2011; Worsnop, Douglas/D-2817-2009 Virtanen, Annele/0000-0002-2917-5344; Laaksonen, Ari/0000-0002-1657-2383; Worsnop, Douglas/0000-0002-8928-8017 0 1520-5029<br/><br/><b>From Duplicate 2 (<i>Real-time chemical composition analysis of particulate emissions from woodchip combustion</i> - Kortelainen, Aki; Joutsensaari, Jorma; Hao, Liqing; Leskinen, Jani; Tiitta, Petri; Jaatinen, Antti; Miettinen, Pasi; Sippula, Olli; Torvela, Tiina; Tissari, Jarkko; Jokiniemi, Jorma; Worsnop, Douglas R.; Smith, James N.; Laaksonen, Ari; Virtanen, Annele)<br/></b><br/>Times Cited: 0 Virtanen, Annele/E-7699-2010; Laaksonen, Ari/B-5094-2011; Worsnop, Douglas/D-2817-2009 Virtanen, Annele/0000-0002-2917-5344; Laaksonen, Ari/0000-0002-1657-2383; Worsnop, Douglas/0000-0002-8928-8017 0 1520-5029},
 private_publication = {false},
 abstract = {Residential wood combustion is one of the major sources of fine particles. The chemical composition of the particles plays a key role in both adverse health and environmental effects. It is important to understand how chemical composition of particulate emissions varies during different combustion processes and conditions. In this work, combustion of wood chips was studied in a moving step-grate burner in different combustion conditions (efficient, intermediate, and smoldering) in the laboratory. The particulate emissions were measured with an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-TOF-AMS). It was found that two phases were occurring frequently in the intermediate and smoldering combustion. Phase 1 took place when gaseous carbon monoxide (CO) was rapidly increasing after the new fuel addition. Phase 2 was a stable, burn-out period with low CO emissions until the new fuel addition and automatic removal of fuel leftovers from the grate. The analysis on the organic aerosol by positive matrix factorization (PMF) extracted out five factors: hydrocarbon-like organic aerosol (HOA), low-volatile-oxidized organic aerosol (LV-OOA), biomass burning organic aerosol (BBOA), and two additional factors of "polycyclic aromatic hydrocarbon (PAH) factor" and "aromatic factor". PAH and LV-OOA were found to be forming mainly during phase 1. HOA showed similar behavior as a PAH factor and LV-OOA in a time series. BBOA was consistent with levoglucosan formation during the combustion and became higher during phase 2. The aromatic factor was mainly composed of fragment ions of n-butyl benzenesulfonamide compound, which was observed in both phases. To our knowledge, this is the first work to report the particulate organics of combustion aerosols and PAH distinguished by PMF. The results prove that the particulate organic emissions can be reduced efficiently when keeping combustion efficiency high. This may help in targeting the efforts on emission reduction better in the future.},
 bibtype = {article},
 author = {Kortelainen, Aki and Joutsensaari, Jorma and Hao, Liqing and Leskinen, Jani and Tiitta, Petri and Jaatinen, Antti and Miettinen, Pasi and Sippula, Olli and Torvela, Tiina and Tissari, Jarkko and Jokiniemi, Jorma and Worsnop, Douglas R. and Smith, James N. and Laaksonen, Ari and Virtanen, Annele},
 doi = {10.1021/ef5019548},
 journal = {Energy and Fuels},
 number = {2}
}

Residential wood combustion is one of the major sources of fine particles. The chemical composition of the particles plays a key role in both adverse health and environmental effects. It is important to understand how chemical composition of particulate emissions varies during different combustion processes and conditions. In this work, combustion of wood chips was studied in a moving step-grate burner in different combustion conditions (efficient, intermediate, and smoldering) in the laboratory. The particulate emissions were measured with an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-TOF-AMS). It was found that two phases were occurring frequently in the intermediate and smoldering combustion. Phase 1 took place when gaseous carbon monoxide (CO) was rapidly increasing after the new fuel addition. Phase 2 was a stable, burn-out period with low CO emissions until the new fuel addition and automatic removal of fuel leftovers from the grate. The analysis on the organic aerosol by positive matrix factorization (PMF) extracted out five factors: hydrocarbon-like organic aerosol (HOA), low-volatile-oxidized organic aerosol (LV-OOA), biomass burning organic aerosol (BBOA), and two additional factors of "polycyclic aromatic hydrocarbon (PAH) factor" and "aromatic factor". PAH and LV-OOA were found to be forming mainly during phase 1. HOA showed similar behavior as a PAH factor and LV-OOA in a time series. BBOA was consistent with levoglucosan formation during the combustion and became higher during phase 2. The aromatic factor was mainly composed of fragment ions of n-butyl benzenesulfonamide compound, which was observed in both phases. To our knowledge, this is the first work to report the particulate organics of combustion aerosols and PAH distinguished by PMF. The results prove that the particulate organic emissions can be reduced efficiently when keeping combustion efficiency high. This may help in targeting the efforts on emission reduction better in the future.

@article{
 title = {Molecular constraints on particle growth during new particle formation},
 type = {article},
 year = {2014},
 keywords = {ammonium,atmospheric aerosol nucleation,bisulfate,boreal forest,chemical-composition,clusters,condensation,ionization mass spectrometer,mass-spectrometry,nano aerosol mass spectrometer,nanoparticle growth,new particle formation,nucleation,rates,secondary organic aerosol,sulfuric acid,sulfuric acid-amine,thermal desorption chemical},
 pages = {6045-6054},
 volume = {41},
 websites = {http://doi.wiley.com/10.1002/2014GL060160},
 month = {8},
 day = {28},
 id = {446c2865-8480-3d4e-969a-5688fd85f442},
 created = {2017-04-12T23:44:37.914Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:18.775Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Bzdek2014a},
 source_type = {article},
 notes = {Times Cited: 0 Zhao, Jun/C-8565-2009 Zhao, Jun/0000-0002-3340-4816 0 1944-8007},
 private_publication = {false},
 abstract = {Atmospheric new particle formation (NPF) produces large numbers of nanoparticles which can ultimately impact climate. A firm understanding of the identity and contribution of the inorganic and carbonaceous species to nanoparticle growth is required to assess the climatic importance of NPF. Here, we combine elemental and molecular nanoparticle composition measurements to better define the composition and contribution of carbonaceous matter to nanoparticle growth in a rural/coastal environment. We show that carbonaceous matter can account for more than half of the mass growth of nanoparticles and its composition is consistent with that expected for extremely low volatility organic compounds. An important novel finding is that the carbonaceous matter must contain a substantial amount of nitrogen, whose molecular identity is not fully understood. The results advance our quantitative understanding of the composition and contribution of carbonaceous matter to nanoparticle growth, which is essential to more accurately predict the climatic impacts of NPF.},
 bibtype = {article},
 author = {Bzdek, Bryan R. and Lawler, Michael J. and Horan, Andrew J. and Pennington, M. Ross and DePalma, Joseph W. and Zhao, Jun and Smith, James N. and Johnston, Murray V.},
 doi = {10.1002/2014GL060160},
 journal = {Geophysical Research Letters},
 number = {16}
}

Atmospheric new particle formation (NPF) produces large numbers of nanoparticles which can ultimately impact climate. A firm understanding of the identity and contribution of the inorganic and carbonaceous species to nanoparticle growth is required to assess the climatic importance of NPF. Here, we combine elemental and molecular nanoparticle composition measurements to better define the composition and contribution of carbonaceous matter to nanoparticle growth in a rural/coastal environment. We show that carbonaceous matter can account for more than half of the mass growth of nanoparticles and its composition is consistent with that expected for extremely low volatility organic compounds. An important novel finding is that the carbonaceous matter must contain a substantial amount of nitrogen, whose molecular identity is not fully understood. The results advance our quantitative understanding of the composition and contribution of carbonaceous matter to nanoparticle growth, which is essential to more accurately predict the climatic impacts of NPF.

@article{
 title = {Chemical characterization of SOA formed from aqueous-phase reactions of phenols with the triplet excited state of carbonyl and hydroxyl radical},
 type = {article},
 year = {2014},
 pages = {13801-13816},
 volume = {14},
 id = {d4891a4d-7047-3463-8657-ce20bd44bd54},
 created = {2019-07-11T17:26:48.233Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-11-02T20:28:34.671Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Yu2014a},
 private_publication = {false},
 abstract = {Phenolic compounds, which are emitted in significant amounts from biomass burning, can undergo fast reactions in atmospheric aqueous phases to form secondary organic aerosol (aqSOA). In this study, we investigate the reactions of phenol (compound with formula C6H5OH)), guaiacol (2-methoxyphenol), and syringol (2,6-dimethoxyphenol) with two major aqueous-phase oxidants - the triplet excited states of an aromatic carbonyl (3C∗) and hydroxyl radical (•OH). We thoroughly characterize the low-volatility species produced from these reactions and interpret their formation mechanisms using aerosol mass spectrometry (AMS), nanospray desorption electrospray ionization mass spectrometry (nano-DESI MS), and ion chromatography (IC). A large number of oxygenated molecules are identified, including oligomers containing up to six monomer units, functionalized monomer and oligomers with carbonyl, carboxyl, and hydroxyl groups, and small organic acid anions (e.g., formate, acetate, oxalate, and malate). The average atomic oxygen-to-carbon (O / C) ratios of phenolic aqSOA are in the range of 0.85-1.23, similar to those of low-volatility oxygenated organic aerosol (LV-OOA) observed in ambient air. The aqSOA compositions are overall similar for the same precursor, but the reactions mediated by 3C∗ are faster than •OH-mediated reactions and produce more oligomers and hydroxylated species at the point when 50% of the phenolic compound has reacted. Profiles determined using a thermodenuder indicate that the volatility of phenolic aqSOA is influenced by both oligomer content and O / C ratio. In addition, the aqSOA shows enhanced light absorption in the UV-visible region, suggesting that aqueous-phase reactions of phenols may contribute to formation of secondary brown carbon in the atmosphere, especially in regions influenced by biomass burning.},
 bibtype = {article},
 author = {Yu, L. and Smith, J. and Laskin, A. and Anastasio, C. and Laskin, J. and Zhang, Q.},
 doi = {10.5194/acp-14-13801-2014},
 journal = {Atmospheric Chemistry and Physics},
 number = {24}
}

Phenolic compounds, which are emitted in significant amounts from biomass burning, can undergo fast reactions in atmospheric aqueous phases to form secondary organic aerosol (aqSOA). In this study, we investigate the reactions of phenol (compound with formula C6H5OH)), guaiacol (2-methoxyphenol), and syringol (2,6-dimethoxyphenol) with two major aqueous-phase oxidants - the triplet excited states of an aromatic carbonyl (3C∗) and hydroxyl radical (•OH). We thoroughly characterize the low-volatility species produced from these reactions and interpret their formation mechanisms using aerosol mass spectrometry (AMS), nanospray desorption electrospray ionization mass spectrometry (nano-DESI MS), and ion chromatography (IC). A large number of oxygenated molecules are identified, including oligomers containing up to six monomer units, functionalized monomer and oligomers with carbonyl, carboxyl, and hydroxyl groups, and small organic acid anions (e.g., formate, acetate, oxalate, and malate). The average atomic oxygen-to-carbon (O / C) ratios of phenolic aqSOA are in the range of 0.85-1.23, similar to those of low-volatility oxygenated organic aerosol (LV-OOA) observed in ambient air. The aqSOA compositions are overall similar for the same precursor, but the reactions mediated by 3C∗ are faster than •OH-mediated reactions and produce more oligomers and hydroxylated species at the point when 50% of the phenolic compound has reacted. Profiles determined using a thermodenuder indicate that the volatility of phenolic aqSOA is influenced by both oligomer content and O / C ratio. In addition, the aqSOA shows enhanced light absorption in the UV-visible region, suggesting that aqueous-phase reactions of phenols may contribute to formation of secondary brown carbon in the atmosphere, especially in regions influenced by biomass burning.

@article{
 title = {Atmospheric submicron aerosol composition and particulate organic nitrate formation in a boreal forestland-urban mixed region},
 type = {article},
 year = {2014},
 keywords = {chemical-composition,cloud interactions,emissions,high-resolution,hydrocarbon-like,mass-spectrometer,particle formation,positive matrix factorization,real plant,semiurban measurement station,source apportionment},
 pages = {13483-13495},
 volume = {14},
 websites = {http://www.atmos-chem-phys.net/14/13483/2014/},
 month = {12},
 day = {18},
 id = {4ef87d0d-3d30-370a-80dd-86ad603c39c0},
 created = {2023-01-31T22:46:06.088Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:06.088Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Hao2014},
 source_type = {Journal Article},
 language = {English},
 notes = {<b>From Duplicate 1 (<i>Atmospheric submicron aerosol composition and particulate organic nitrate formation in a boreal forestland-urban mixed region</i> - Hao, L. Q.; Kortelainen, A.; Romakkaniemi, S.; Portin, H.; Jaatinen, A.; Leskinen, A.; Komppula, M.; Miettinen, P.; Sueper, D.; Pajunoja, A.; Smith, J. N.; Lehtinen, K. E.J.; Worsnop, D. R.; Laaksonen, A.; Virtanen, A.)<br/></b><br/>ISI Document Delivery No.: AZ0TI<br/>Times Cited: 2<br/>Cited Reference Count: 48<br/>Hao, L. Q. Kortelainen, A. Romakkaniemi, S. Portin, H. Jaatinen, A. Leskinen, A. Komppula, M. Miettinen, P. Sueper, D. Pajunoja, A. Smith, J. N. Lehtinen, K. E. J. Worsnop, D. R. Laaksonen, A. Virtanen, A.<br/>UEF Postdoc Research Foundation [930275]; University of Eastern Finland; Academy of the Finland Centre of Excellence [272041]; European Recearch Council [335478]; US Department of Energy; US National Science Foundation<br/>This work was supported by the UEF Postdoc Research Foundation (no. 930275), strategic funding from the University of Eastern Finland and Academy of the Finland Centre of Excellence (grant no. 272041), European Recearch Council (Starting Grant 335478), S. Romakkaniemi and A. Virtanen acknowledge the Academy of Finland for the Academy Research Fellow positions (decisions 283031 and 252741). J. N. Smith acknowledges support from the US Department of Energy. The National Center for Atmospheric Research is sponsored by the US National Science Foundation.<br/>Copernicus gesellschaft mbh<br/>Gottingen<br/><br/><b>From Duplicate 2 (<i>Atmospheric submicron aerosol composition and particulate organic nitrate formation in a boreal forestland-urban mixed region</i> - Hao, L. Q.; Kortelainen, A.; Romakkaniemi, S.; Portin, H.; Jaatinen, A.; Leskinen, A.; Komppula, M.; Miettinen, P.; Sueper, D.; Pajunoja, A.; Smith, J. N.; Lehtinen, K. E.J. J; Worsnop, D. R.; Laaksonen, A.; Virtanen, A.)<br/></b><br/><b>From Duplicate 1 (<i>Atmospheric submicron aerosol composition and particulate organic nitrate formation in a boreal forestland-urban mixed region</i> - Hao, L. Q.; Kortelainen, A.; Romakkaniemi, S.; Portin, H.; Jaatinen, A.; Leskinen, A.; Komppula, M.; Miettinen, P.; Sueper, D.; Pajunoja, A.; Smith, J. N.; Lehtinen, K. E.J.; Worsnop, D. R.; Laaksonen, A.; Virtanen, A.)<br/></b><br/>Times Cited: 1<br/><br/><b>From Duplicate 2 (<i>Atmospheric submicron aerosol composition and particulate organic nitrate formation in a boreal forestland–urban mixed region</i> - Hao, L Q; Kortelainen, A; Romakkaniemi, S; Portin, H; Jaatinen, A; Leskinen, A; Komppula, M; Miettinen, P; Sueper, D; Pajunoja, A; Smith, J N; Lehtinen, K E J; Worsnop, D R; Laaksonen, A; Virtanen, A)<br/></b><br/>ISI Document Delivery No.: AZ0TI<br/>Times Cited: 2<br/>Cited Reference Count: 48<br/>Hao, L. Q. Kortelainen, A. Romakkaniemi, S. Portin, H. Jaatinen, A. Leskinen, A. Komppula, M. Miettinen, P. Sueper, D. Pajunoja, A. Smith, J. N. Lehtinen, K. E. J. Worsnop, D. R. Laaksonen, A. Virtanen, A.<br/>UEF Postdoc Research Foundation [930275]; University of Eastern Finland; Academy of the Finland Centre of Excellence [272041]; European Recearch Council [335478]; US Department of Energy; US National Science Foundation<br/>This work was supported by the UEF Postdoc Research Foundation (no. 930275), strategic funding from the University of Eastern Finland and Academy of the Finland Centre of Excellence (grant no. 272041), European Recearch Council (Starting Grant 335478), S. Romakkaniemi and A. Virtanen acknowledge the Academy of Finland for the Academy Research Fellow positions (decisions 283031 and 252741). J. N. Smith acknowledges support from the US Department of Energy. The National Center for Atmospheric Research is sponsored by the US National Science Foundation.<br/>Copernicus gesellschaft mbh<br/>Gottingen<br/><br/><b>From Duplicate 3 (<i>Atmospheric submicron aerosol composition and particulate organic nitrate formation in a boreal forestland-urban mixed region</i> - Hao, L Q; Kortelainen, A; Romakkaniemi, S; Portin, H; Jaatinen, A; Leskinen, A; Komppula, M; Miettinen, P; Sueper, D; Pajunoja, A; Smith, J N; Lehtinen, K E J; Worsnop, D R; Laaksonen, A; Virtanen, A)<br/></b><br/>Times Cited: 2 Virtanen, Annele/E-7699-2010; Leskinen, Ari/D-8658-2013; Laaksonen, Ari/B-5094-2011; Worsnop, Douglas/D-2817-2009 Virtanen, Annele/0000-0002-2917-5344; Laaksonen, Ari/0000-0002-1657-2383; Worsnop, Douglas/0000-0002-8928-8017 0 2 1680-7324},
 private_publication = {false},
 abstract = {The Puijo aerosol-cloud observation station is a unique measurement site for its location in the mixed region between the boreal forestland and the municipality of Kuopio, Finland. A measurement campaign was carried out at the station during fall 2010. An Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-Tof-AMS) was deployed to characterize the atmospheric submicron aerosols. Positive matrix factorization (PMF) was applied to the unified high-resolution mass spectra organic species with NO+ and NO2+ ions to discover the intrinsic relationships between the organic and inorganic species and their daily cycles. On average, the submicron aerosols in this study were dominated by organic and sulfate species, composing 48.2 and 28.7% of total observed aerosol mass, respectively, with smaller contributions from ammonium (9.3 %), nitrate (4.9 %), chloride (0.8 %) and BC (8.1 %). The sources of these species included the primary emissions originating from the city area, secondary formation from both natural and anthropogenic emissions and regional transport. The PMF analysis succeeded in separating the mixed organic and inorganic spectra into three distinct organic and one inorganic factors. For organic factors, the semi-volatile oxygenated organic aerosol (SVOOA) and low-volatility oxygenated OA (LVOOA) accounted for 54.8 and 36.3% of total organic masses, respectively, while the hydrocarbon-like organic aerosol (HOA) accounted for 8.9% of total organics, with its main source from urban emissions. The inorganic factor is identified as NH4NO3, comprising 6.9% of the fitted aerosol mass by PMF. Based on the PMF results, the nitrate species were separated into organic and inorganic components, with the organic nitrates contributing one-third of the total nitrate mass. The results highlight both anthropogenic and biogenic emissions as important atmospheric aerosol sources in a forest-urban mixed region.},
 bibtype = {article},
 author = {Hao, L. Q. and Kortelainen, A. and Romakkaniemi, S. and Portin, H. and Jaatinen, A. and Leskinen, A. and Komppula, M. and Miettinen, P. and Sueper, D. and Pajunoja, A. and Smith, J. N. and Lehtinen, K. E.J. J and Worsnop, D. R. and Laaksonen, A. and Virtanen, A.},
 doi = {10.5194/acp-14-13483-2014},
 journal = {Atmospheric Chemistry and Physics},
 number = {24}
}

The Puijo aerosol-cloud observation station is a unique measurement site for its location in the mixed region between the boreal forestland and the municipality of Kuopio, Finland. A measurement campaign was carried out at the station during fall 2010. An Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-Tof-AMS) was deployed to characterize the atmospheric submicron aerosols. Positive matrix factorization (PMF) was applied to the unified high-resolution mass spectra organic species with NO+ and NO2+ ions to discover the intrinsic relationships between the organic and inorganic species and their daily cycles. On average, the submicron aerosols in this study were dominated by organic and sulfate species, composing 48.2 and 28.7% of total observed aerosol mass, respectively, with smaller contributions from ammonium (9.3 %), nitrate (4.9 %), chloride (0.8 %) and BC (8.1 %). The sources of these species included the primary emissions originating from the city area, secondary formation from both natural and anthropogenic emissions and regional transport. The PMF analysis succeeded in separating the mixed organic and inorganic spectra into three distinct organic and one inorganic factors. For organic factors, the semi-volatile oxygenated organic aerosol (SVOOA) and low-volatility oxygenated OA (LVOOA) accounted for 54.8 and 36.3% of total organic masses, respectively, while the hydrocarbon-like organic aerosol (HOA) accounted for 8.9% of total organics, with its main source from urban emissions. The inorganic factor is identified as NH4NO3, comprising 6.9% of the fitted aerosol mass by PMF. Based on the PMF results, the nitrate species were separated into organic and inorganic components, with the organic nitrates contributing one-third of the total nitrate mass. The results highlight both anthropogenic and biogenic emissions as important atmospheric aerosol sources in a forest-urban mixed region.

@article{
 title = {Increased hygroscopicity of Arizona Test Dust seeds by secondary organic aerosol coating from α-pinene ozonolysis},
 type = {article},
 year = {2014},
 pages = {182-190},
 volume = {19},
 websites = {http://www.borenv.net/BER/pdfs/ber19/ber19B-182.pdf},
 id = {56a79b7b-cb28-3326-bafc-082da95898b7},
 created = {2023-01-31T22:46:06.734Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:06.734Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Keskinen2014},
 source_type = {Journal Article},
 notes = {<b>From Duplicate 1 (<i>Increased hygroscopicity of Arizona Test Dust seeds by secondary organic aerosol coating from α-pinene ozonolysis</i> - Keskinen, Helmi; Kortelainen, Aki Matti; Jaatinen, Antti; Yli-Pirilä, Pasi; Joutsensaari, Jorma; Romakkaniemi, Sami; Hao, Li Qing; Miettinen, Pasi; Virtanen, Annele; Worsnop, Douglas R.; Laaksonen, Ari; Smith, James N.; Torvela, Tiina; Laaksonen, Ari; Worsnop, Douglas R.; Smith, James N.; Romakkaniemi, Sami)<br/></b><br/><b>From Duplicate 1 (<i>Increased hygroscopicity of Arizona Test Dust seeds by secondary organic aerosol coating from alpha-pinene ozonolysis</i> - Keskinen, Helmi; Kortelainen, Aki-Matti; Jaatinen, Antti; Yli-Pirila, Pasi; Joutsensaari, Jorma; Romakkaniemi, Sami; Hao, Li-Qing; Torvela, Tiina; Miettinen, Pasi; Virtanen, Annele; Worsnop, Douglas R; Laaksonen, An; Smith, James N)<br/></b><br/>Times Cited: 0 Si B Romakkaniemi, Sami/C-1308-2012; Laaksonen, Ari/B-5094-2011; Worsnop, Douglas/D-2817-2009; Virtanen, Annele/E-7699-2010 Laaksonen, Ari/0000-0002-1657-2383; Worsnop, Douglas/0000-0002-8928-8017; Virtanen, Annele/0000-0002-2917-5344 0 1797-2469<br/><br/><b>From Duplicate 2 (<i>Increased hygroscopicity of Arizona Test Dust seeds by secondary organic aerosol coating from α-pinene ozonolysis</i> - Keskinen, Helmi; Kortelainen, Aki Matti; Jaatinen, Antti; Yli-Pirilä, Pasi; Joutsensaari, Jorma; Romakkaniemi, Sami; Hao, Li Qing; Miettinen, Pasi; Virtanen, Annele; Worsnop, Douglas R.; Laaksonen, Ari; Smith, James N.; Torvela, Tiina; Laaksonen, Ari; Worsnop, Douglas R.; Smith, James N.; Romakkaniemi, Sami)<br/></b><br/>Times Cited: 0<br/>Si<br/>B<br/><br/><b>From Duplicate 2 (<i>Increased hygroscopicity of Arizona Test Dust seeds by secondary organic aerosol coating from α-pinene ozonolysis</i> - Keskinen, Helmi; Kortelainen, Aki Matti; Jaatinen, Antti; Yli-Pirilä, Pasi; Joutsensaari, Jorma; Romakkaniemi, Sami; Hao, Li Qing; Miettinen, Pasi; Virtanen, Annele; Worsnop, Douglas R.; Laaksonen, Ari; Smith, James N.; Torvela, Tiina; Laaksonen, Ari; Worsnop, Douglas R.; Smith, James N.; Romakkaniemi, Sami)<br/></b><br/>Times Cited: 0<br/>Si<br/>B},
 private_publication = {false},
 abstract = {Organic compounds can enhance the hygroscopic properties of insoluble dust particles and thereby affect their cloud condensation nuclei activity in the atmosphere. In this study, Arizona Test Dust (ATD) particles were exposed to oxidized organic vapors from the ozonolysis of α-pinene in a laboratory chamber. The particle size-dependent morphology, inorganic and organic composition and hygroscopic properties were studied. The dust consisted of particles with a range of morphologies from spherical to geometrical, with a size range from 50 nm to 1 μm. Exposure to oxidized organics resulted in a separate mode of secondary organic aerosol (SOA) particles with size ranging below 100 nm and a well-mixed ATD + SOA mode at larger sizes. The O:C mole ratio for the organics produced from α-pinene ozonolysis was stable at 0.4 ± 0.05 in all experiments. The results showed that the hygroscopicities of the ATD particles with a diameter of 100–150 nm were enhanced by a factor of four with the addition of SOA, corresponding to a particulate organic volume fraction of ~0.6 and an average κ of 0.09.},
 bibtype = {article},
 author = {Keskinen, Helmi and Kortelainen, Aki Matti and Jaatinen, Antti and Yli-Pirilä, Pasi and Joutsensaari, Jorma and Romakkaniemi, Sami and Hao, Li Qing and Miettinen, Pasi and Virtanen, Annele and Worsnop, Douglas R. and Laaksonen, Ari and Smith, James N. and Torvela, Tiina and Laaksonen, Ari and Worsnop, Douglas R. and Smith, James N. and Romakkaniemi, Sami},
 journal = {Boreal Environment Research}
}

Organic compounds can enhance the hygroscopic properties of insoluble dust particles and thereby affect their cloud condensation nuclei activity in the atmosphere. In this study, Arizona Test Dust (ATD) particles were exposed to oxidized organic vapors from the ozonolysis of α-pinene in a laboratory chamber. The particle size-dependent morphology, inorganic and organic composition and hygroscopic properties were studied. The dust consisted of particles with a range of morphologies from spherical to geometrical, with a size range from 50 nm to 1 μm. Exposure to oxidized organics resulted in a separate mode of secondary organic aerosol (SOA) particles with size ranging below 100 nm and a well-mixed ATD + SOA mode at larger sizes. The O:C mole ratio for the organics produced from α-pinene ozonolysis was stable at 0.4 ± 0.05 in all experiments. The results showed that the hygroscopicities of the ATD particles with a diameter of 100–150 nm were enhanced by a factor of four with the addition of SOA, corresponding to a particulate organic volume fraction of ~0.6 and an average κ of 0.09.

@article{
 title = {Modeling ultrafine particle growth at a pine forest site influenced by anthropogenic pollution during BEACHON-RoMBAS 2011},
 type = {article},
 year = {2014},
 keywords = {atmospheric aerosol nucleation,boundary-layer,chemical-composition,condensation,events,global ccn,impact,number concentration,organic-compounds,sulfuric-acid concentration},
 pages = {11011-11029},
 volume = {14},
 id = {5e2006fe-3f4c-3916-835a-3c2562435079},
 created = {2023-01-31T22:46:07.009Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2024-05-14T23:31:09.245Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Cui2014},
 source_type = {Journal Article},
 language = {English},
 notes = {<b>From Duplicate 1 (<i>Modeling ultrafine particle growth at a pine forest site influenced by anthropogenic pollution during BEACHON-RoMBAS 2011</i> - Cui, Y. Y.; Hodzic, A.; Smith, J. N.; Ortega, J.; Brioude, J.; Matsui, H.; Levin, E. J.T.; Turnipseed, A.; Winkler, P.; De Foy, B.)<br/></b><br/>ISI Document Delivery No.: AS3GO<br/>Times Cited: 3<br/>Cited Reference Count: 69<br/>Cui, Y. Y. Hodzic, A. Smith, J. N. Ortega, J. Brioude, J. Matsui, H. Levin, E. J. T. Turnipseed, A. Winkler, P. de Foy, B.<br/>DOE [DE-FG0208ER64627]; NCAR; NCAR's Advanced Study Program/Graduate Visitor Program; Austrian Science Fund (FWF) [J3198-N21]; National Science Foundation [ATM-0919317]; US Department of Energy [DE-SC0006861]<br/>The authors would like to acknowledge data contributions, interesting discussions and editing from Lisa Kaser (University of Innsbruck, Austria, and ASP postdoc at National Center for Atmospheric Research, NCAR), Ezra Levin (Colorado State University), David Gochis (National Center for Atmospheric Research, NCAR), Jerome Fast (Pacific Northwest National Laboratory, PNNL), and Christoph Knote (National Center for Atmospheric Research, NCAR). This research has been supported by the DOE DE-FG0208ER64627 grant, and NCAR which is operated by the University Corporation for Atmospheric Research on behalf of the National Science Foundation. Authors would like to thank in particular the generous support of the NCAR's Advanced Study Program/Graduate Visitor Program. P. Winkler acknowledges financial support from the Austrian Science Fund (FWF, project no. J3198-N21). J. N. Smith acknowledges support from the National Science Foundation (ATM-0919317) and US Department of Energy (DE-SC0006861).<br/>Copernicus gesellschaft mbh<br/>Gottingen<br/><br/><b>From Duplicate 2 (<i>Modeling ultrafine particle growth at a pine forest site influenced by anthropogenic pollution during BEACHON-RoMBAS 2011</i> - Cui, Y Y; Hodzic, A; Smith, J N; Ortega, J; Brioude, J; Matsui, H; Levin, E J T; Turnipseed, A; Winkler, P; de Foy, B)<br/></b><br/>Times Cited: 1},
 folder_uuids = {9ff79d6a-4400-4745-884f-783b10d8942c},
 private_publication = {false},
 abstract = {Formation and growth of ultrafine particles is crudely represented in chemistry-climate models, contributing to uncertainties in aerosol composition, size distribution, and aerosol effects on cloud condensation nuclei (CCN) concentrations. Measurements of ultrafine particles, their precursor gases, and meteorological parameters were performed in a ponderosa pine forest in the Colorado Front Range in July-August 2011, and were analyzed to study processes leading to small particle burst events (PBEs) which were characterized by an increase in the number concentrations of ultrafine 4-30 nm diameter size particles. These measurements suggest that PBEs were associated with the arrival at the site of anthropogenic pollution plumes midday to early afternoon. During PBEs, number concentrations of 4-30 nm diameter particles typically exceeded 104 cm3, and these elevated concentrations coincided with increased SO2 and monoterpene concentrations, and led to a factor-of-2 increase in CCN concentrations at 0.5% supersaturation. The PBEs were simulated using the regional WRF-Chem model, which was extended to account for ultrafine particle sizes starting at 1 nm in diameter, to include an empirical activation nucleation scheme in the planetary boundary layer, and to explicitly simulate the subsequent growth of Aitken particles (10-100 nm) by condensation of organic and inorganic vapors. The updated model reasonably captured measured aerosol number concentrations and size distribution during PBEs, as well as ground-level CCN concentrations. Model results suggest that sulfuric acid originating from anthropogenic SO2 triggered PBEs, and that the condensation of monoterpene oxidation products onto freshly nucleated particles contributes to their growth. The simulated growth rate of ∼ 3.4 nm h1 for 4-40 nm diameter particles was comparable to the measured average value of 2.3 nm h1. Results also suggest that the presence of PBEs tends to modify the composition of sub-20 nm diameter particles, leading to a higher mass fraction of sulfate aerosols. Sensitivity simulations suggest that the representation of nucleation processes in the model largely influences the predicted number concentrations and thus CCN concentrations. We estimate that nucleation contributes 67% of surface CCN at 0.5% supersaturation in this pine forest environment.},
 bibtype = {article},
 author = {Cui, Y. Y. and Hodzic, A. and Smith, J. N. and Ortega, J. and Brioude, J. and Matsui, H. and Levin, E. J.T. T and Turnipseed, A. and Winkler, P. and de Foy, B.},
 doi = {10.5194/acp-14-11011-2014},
 journal = {Atmospheric Chemistry and Physics},
 number = {20}
}

Formation and growth of ultrafine particles is crudely represented in chemistry-climate models, contributing to uncertainties in aerosol composition, size distribution, and aerosol effects on cloud condensation nuclei (CCN) concentrations. Measurements of ultrafine particles, their precursor gases, and meteorological parameters were performed in a ponderosa pine forest in the Colorado Front Range in July-August 2011, and were analyzed to study processes leading to small particle burst events (PBEs) which were characterized by an increase in the number concentrations of ultrafine 4-30 nm diameter size particles. These measurements suggest that PBEs were associated with the arrival at the site of anthropogenic pollution plumes midday to early afternoon. During PBEs, number concentrations of 4-30 nm diameter particles typically exceeded 104 cm3, and these elevated concentrations coincided with increased SO2 and monoterpene concentrations, and led to a factor-of-2 increase in CCN concentrations at 0.5% supersaturation. The PBEs were simulated using the regional WRF-Chem model, which was extended to account for ultrafine particle sizes starting at 1 nm in diameter, to include an empirical activation nucleation scheme in the planetary boundary layer, and to explicitly simulate the subsequent growth of Aitken particles (10-100 nm) by condensation of organic and inorganic vapors. The updated model reasonably captured measured aerosol number concentrations and size distribution during PBEs, as well as ground-level CCN concentrations. Model results suggest that sulfuric acid originating from anthropogenic SO2 triggered PBEs, and that the condensation of monoterpene oxidation products onto freshly nucleated particles contributes to their growth. The simulated growth rate of ∼ 3.4 nm h1 for 4-40 nm diameter particles was comparable to the measured average value of 2.3 nm h1. Results also suggest that the presence of PBEs tends to modify the composition of sub-20 nm diameter particles, leading to a higher mass fraction of sulfate aerosols. Sensitivity simulations suggest that the representation of nucleation processes in the model largely influences the predicted number concentrations and thus CCN concentrations. We estimate that nucleation contributes 67% of surface CCN at 0.5% supersaturation in this pine forest environment.

@article{
 title = {Secondary Organic Aerosol Formation and Organic Nitrate Yield from NO3 Oxidation of Biogenic Hydrocarbons},
 type = {article},
 year = {2014},
 keywords = {alpha-pinene,emissions,gas,isoprene,model,monoterpenes,particle formation,product,radicals,soa formation},
 pages = {11944-11953},
 volume = {48},
 id = {461c4914-fd40-3571-89f8-adb5169a6166},
 created = {2023-01-31T22:46:07.292Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:07.292Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Fry2014a},
 source_type = {Journal Article},
 language = {English},
 notes = {<b>From Duplicate 1 (<i>Secondary organic aerosol formation and organic nitrate yield from NO3 oxidation of biogenic hydrocarbons</i> - Fry, Juliane L.; Draper, Danielle C.; Barsanti, Kelley C.; Smith, James N.; Ortega, John; Winkler, Paul M.; Lawler, Michael J.; Brown, Steven S.; Edwards, Peter M.; Cohen, Ronald C.; Lee, Lance)<br/></b><br/>ISI Document Delivery No.: AR5RJ<br/>Times Cited: 7<br/>Cited Reference Count: 41<br/>Fry, Juliane L. Draper, Danielle C. Barsanti, Kelley C. Smith, James N. Ortega, John Winkle, Paul M. Lawler, Michael J. Brown, Steven S. Edwards, Peter M. Cohen, Ronald C. Lee, Lance<br/>NOAA Climate Program Office's AC4 program [NA13OAR4310070]; Finnish Academy [251007]; U.S. Department of Energy [DE-SC0006861]; Austrian Science Fund (FWF) [J3198-N21]; National Science Foundation<br/>J.L.F. gratefully acknowledges sabbatical support from the Cooperative Institute for Research in Environmental Science (CIRES) and the National Center for Atmospheric Research Visiting Scholars Program, and J.L.F. and S.S.B. acknowledge funding from the NOAA Climate Program Office's AC4 program (Grant No. NA13OAR4310070). We thank Serena Chung, Peter McMurry, Paul Ziemann, and John Orlando for helpful discussions. J.N.S. acknowledges funding from the Finnish Academy (Grant No. 251007) and U.S. Department of Energy (Grant No. DE-SC0006861). P.M.W. acknowledges financial support from the Austrian Science Fund (FWF, Project No. J3198-N21). The National Center for Atmospheric Research is sponsored by the National Science Foundation.<br/>Amer chemical soc<br/>Washington<br/><br/><b>From Duplicate 2 (<i>Secondary Organic Aerosol Formation and Organic Nitrate Yield from NO3 Oxidation of Biogenic Hydrocarbons</i> - Fry, Juliane L; Draper, Danielle C; Barsanti, Kelley C; Smith, James N; Ortega, John; Winkle, Paul M; Lawler, Michael J; Brown, Steven S; Edwards, Peter M; Cohen, Ronald C; Lee, Lance)<br/></b><br/>Times Cited: 0},
 private_publication = {false},
 abstract = {The secondary organic aerosol (SOA) mass yields from NO3 oxidation of a series of biogenic volatile organic compounds (BVOCs), consisting of five monoterpenes and one sesquiterpene (α-pinene, β-pinene, Δ-3-carene, limonene, sabinene, and β-caryophyllene), were investigated in a series of continuous flow experiments in a 10 m3 indoor Teflon chamber. By making in situ measurements of the nitrate radical and employing a kinetics box model, we generate time-dependent yield curves as a function of reacted BVOC. SOA yields varied dramatically among the different BVOCs, from zero for α-pinene to 38-65% for Δ-3-carene and 86% for β-caryophyllene at mass loading of 10 μg m-3, suggesting that model mechanisms that treat all NO3 + monoterpene reactions equally will lead to errors in predicted SOA depending on each location's mix of BVOC emissions. In most cases, organonitrate is a dominant component of the aerosol produced, but in the case of α-pinene, little organonitrate and no aerosol is formed.},
 bibtype = {article},
 author = {Fry, Juliane L. and Draper, Danielle C. and Barsanti, Kelley C. and Smith, James N. and Ortega, John and Winkle, Paul M and Lawler, Michael J. and Brown, Steven S. and Edwards, Peter M. and Cohen, Ronald C. and Lee, Lance and Winkler, Paul M. and Lawler, Michael J. and Brown, Steven S. and Edwards, Peter M. and Cohen, Ronald C. and Lee, Lance},
 doi = {10.1021/es502204x},
 journal = {Environmental Science and Technology},
 number = {20}
}

The secondary organic aerosol (SOA) mass yields from NO3 oxidation of a series of biogenic volatile organic compounds (BVOCs), consisting of five monoterpenes and one sesquiterpene (α-pinene, β-pinene, Δ-3-carene, limonene, sabinene, and β-caryophyllene), were investigated in a series of continuous flow experiments in a 10 m3 indoor Teflon chamber. By making in situ measurements of the nitrate radical and employing a kinetics box model, we generate time-dependent yield curves as a function of reacted BVOC. SOA yields varied dramatically among the different BVOCs, from zero for α-pinene to 38-65% for Δ-3-carene and 86% for β-caryophyllene at mass loading of 10 μg m-3, suggesting that model mechanisms that treat all NO3 + monoterpene reactions equally will lead to errors in predicted SOA depending on each location's mix of BVOC emissions. In most cases, organonitrate is a dominant component of the aerosol produced, but in the case of α-pinene, little organonitrate and no aerosol is formed.

@article{
 title = {The third Pallas Cloud Experiment: Consistency between the aerosol hygroscopic growth and CCN activity},
 type = {article},
 year = {2014},
 keywords = {arctic background site,boreal forest,campaign,condensation nuclei,droplet activation,experiment 2nd pace,finland,mass-spectrometer,microphysics,northern,particles},
 pages = {368-382},
 volume = {19},
 websites = {http://www.borenv.net/BER/pdfs/ber19/ber19B-368.pdf},
 id = {60f615b5-26ab-31d1-938c-1472215fb713},
 created = {2023-01-31T22:46:08.417Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:08.417Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Jaatinen2014a},
 source_type = {Journal Article},
 language = {English},
 notes = {<b>From Duplicate 1 (<i>The third Pallas Cloud Experiment: Consistency between the aerosol hygroscopic growth and CCN activity</i> - Jaatinen, Antti; Romakkaniemi, Sami; Hao, Li Qing; Kortelainen, Aki; Miettinen, Pasi; Mikkonen, Santtu; Smith, James N.; Virtanen, Annele; Laaksonen, Ari; Anttila, Tatu; Hyvärinen, Antti Pekka; Smith, James N.; Laaksonen, Ari; Smith, James N.; Romakkaniemi, Sami)<br/></b><br/>ISI Document Delivery No.: AQ2XU<br/>Times Cited: 3<br/>Cited Reference Count: 39<br/>Jaatinen, Antti Romakkaniemi, Sami Anttila, Tatu Hyvarinen, Antti-Pekka Hao, Li-Qing Kortelainen, Aki Miettinen, Pasi Mikkonen, Santtu Smith, James N. Virtanen, Annele Laaksonen, Ari<br/>Academy of Finland Center of Excellence program [1118615]; Kone foundation; Saastamoinen Foundation; Finnish Academy; US Department of Energy; US National Science Foundation; UEF Postdoc Research Foundation [930275]<br/>The work has been supported financially by the Academy of Finland Center of Excellence program (project no. 1118615). A.J. was supported by the Kone foundation. S.R. acknowledges the Academy of Finland for the Academy Research Fellow position (decision 267514). J.S. acknowledges support from the Saastamoinen Foundation, the Finnish Academy, and the US Department of Energy. NCAR is supported by the US National Science Foundation. H.L. acknowledges the financial support of the UEF Postdoc Research Foundation (no. 930275).<br/>Finnish environment inst<br/>Helsinki<br/>B<br/>Si},
 private_publication = {false},
 abstract = {Measurements of aerosol chemical and hygroscopic properties and cloud\ncondensation nuclei were carried out as a part of the third Pallas Cloud\nExperiment. In this study, the aerosol hygroscopicity parameter, kappa,\nwas determined using data from instruments operating in the\nsub-saturated and supersaturated water vapour regimes, as well as from\nmeasurements of aerosol chemical composition. During the campaign, kappa\nvaried from similar to 0.01 to similar to 0.37 as derived by Cloud\nCondensation Nuclei counter and Hygroscopic Tandem Differential Mobility\nanalyser data, and from similar to 0.13 to similar to 0.60 as derived\nfrom Aerosol Mass Spectrometer data, the average values being 0.11 and\n0.29, respectively. CCN closure calculations showed that the\nsub-saturated growth factor retrieved CCN concentration is lower than\nthe measured one. Overall, at the Pallas site, aerosol hygroscopicity\nwas size dependent with hygroscopicity increasing with size. Hence, size\ndependent information on composition is needed to predict CCN\nconcentrations relevant to cloud droplet formation.},
 bibtype = {article},
 author = {Jaatinen, Antti and Romakkaniemi, Sami and Hao, Li Qing and Kortelainen, Aki and Miettinen, Pasi and Mikkonen, Santtu and Smith, James N. and Virtanen, Annele and Laaksonen, Ari and Anttila, Tatu and Hyvärinen, Antti Pekka and Smith, James N. and Laaksonen, Ari and Smith, James N. and Romakkaniemi, Sami},
 journal = {Boreal Environment Research}
}

Measurements of aerosol chemical and hygroscopic properties and cloud\ncondensation nuclei were carried out as a part of the third Pallas Cloud\nExperiment. In this study, the aerosol hygroscopicity parameter, kappa,\nwas determined using data from instruments operating in the\nsub-saturated and supersaturated water vapour regimes, as well as from\nmeasurements of aerosol chemical composition. During the campaign, kappa\nvaried from similar to 0.01 to similar to 0.37 as derived by Cloud\nCondensation Nuclei counter and Hygroscopic Tandem Differential Mobility\nanalyser data, and from similar to 0.13 to similar to 0.60 as derived\nfrom Aerosol Mass Spectrometer data, the average values being 0.11 and\n0.29, respectively. CCN closure calculations showed that the\nsub-saturated growth factor retrieved CCN concentration is lower than\nthe measured one. Overall, at the Pallas site, aerosol hygroscopicity\nwas size dependent with hygroscopicity increasing with size. Hence, size\ndependent information on composition is needed to predict CCN\nconcentrations relevant to cloud droplet formation.

@article{
 title = {Size-resolved aerosol composition and its link to hygroscopicity at a forested site in Colorado},
 type = {article},
 year = {2014},
 pages = {2657-2667},
 volume = {14},
 websites = {http://www.atmos-chem-phys.net/14/2657/2014/},
 month = {3},
 day = {14},
 id = {0468801e-a7a6-3049-ba02-b4a29bc22f31},
 created = {2023-01-31T22:46:08.808Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:08.808Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Levin2014},
 source_type = {article},
 notes = {<b>From Duplicate 2 (<i>Size-resolved aerosol composition and its link to hygroscopicity at a forested site in Colorado</i> - Levin, E. J.T.; Prenni, A. J.; Palm, B. B.; Day, D. A.; Campuzano-Jost, P.; Winkler, P. M.; Kreidenweis, S. M.; Demott, P. J.; Jimenez, J. L.; Smith, J. N.)<br/></b><br/>Times Cited: 7},
 private_publication = {false},
 abstract = {The ability of particles composed wholly or partially of biogenic secondary organic compounds to serve as cloud condensation nuclei (CCN) is a key characteristic that helps to define their roles in linking biogeochemical and water cycles. In this paper, we describe size-resolved (14-350 nm) CCN measurements from the Manitou Experimental Forest in Colorado, where particle compositions were expected to have a large biogenic component. These measurements were conducted for 1 year as part of the Bio-hydro-atmosphere Interactions of Energy, Aerosols, Carbon, H2O, Organics, and Nitrogen program and determined the aerosol hygroscopicity parameter, kappa, at five water supersaturations between similar to 0.14% and similar to 0.97%. The average kappa value over the entire study and all supersaturations was kappa(avg) = 0.16 +/- 0.08. Kappa values decreased slightly with increasing supersaturation, suggesting a change in aerosol composition with dry diameter. Furthermore, some seasonal variability was observed with increased CCN concentrations and activated particle number fraction, but slightly decreased hygroscopicity, during the summer. Small particle events, which may indicate new particle formation, were observed throughout the study period, especially in the summer, leading to increases in CCN concentration, followed by a gradual increase in the aerosol mode size. The condensing material appeared to be predominantly composed of organic compounds and led to a small decrease in k at the larger activation diameters during and immediately after those events.},
 bibtype = {article},
 author = {Levin, E. J.T. and Prenni, A. J. and Palm, B. B. and Day, D. A. and Campuzano-Jost, P. and Winkler, P. M. and Kreidenweis, S. M. and Demott, P. J. and Jimenez, J. L. and Smith, J. N.},
 doi = {10.5194/acp-14-2657-2014},
 journal = {Atmospheric Chemistry and Physics},
 number = {5}
}

The ability of particles composed wholly or partially of biogenic secondary organic compounds to serve as cloud condensation nuclei (CCN) is a key characteristic that helps to define their roles in linking biogeochemical and water cycles. In this paper, we describe size-resolved (14-350 nm) CCN measurements from the Manitou Experimental Forest in Colorado, where particle compositions were expected to have a large biogenic component. These measurements were conducted for 1 year as part of the Bio-hydro-atmosphere Interactions of Energy, Aerosols, Carbon, H2O, Organics, and Nitrogen program and determined the aerosol hygroscopicity parameter, kappa, at five water supersaturations between similar to 0.14% and similar to 0.97%. The average kappa value over the entire study and all supersaturations was kappa(avg) = 0.16 +/- 0.08. Kappa values decreased slightly with increasing supersaturation, suggesting a change in aerosol composition with dry diameter. Furthermore, some seasonal variability was observed with increased CCN concentrations and activated particle number fraction, but slightly decreased hygroscopicity, during the summer. Small particle events, which may indicate new particle formation, were observed throughout the study period, especially in the summer, leading to increases in CCN concentration, followed by a gradual increase in the aerosol mode size. The condensing material appeared to be predominantly composed of organic compounds and led to a small decrease in k at the larger activation diameters during and immediately after those events.

@article{
 title = {High levels of molecular chlorine in the Arctic atmosphere},
 type = {article},
 year = {2014},
 pages = {91-94},
 volume = {7},
 websites = {http://www.nature.com/doifinder/10.1038/ngeo2046},
 id = {3d8f7a54-ea58-37e7-8907-ca06122cc2d5},
 created = {2023-01-31T22:46:09.191Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:09.191Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Liao2014},
 source_type = {article},
 notes = {<b>From Duplicate 1 (<i>High levels of molecular chlorine in the Arctic atmosphere</i> - Liao, Jin; Huey, L. Gregory; Liu, Zhen; Tanner, David J.; Cantrell, Chris A.; Orlando, John J.; Flocke, Frank M.; Shepson, Paul B.; Weinheimer, Andrew J.; Hall, Samuel R.; Ullmann, Kirk; Beine, Harry J.; Wang, Yuhang; Ingall, Ellery D.; Stephens, Chelsea R.; Hornbrook, Rebecca S.; Apel, Eric C.; Riemer, Daniel; Fried, Alan; Mauldin, Roy L.; Smith, James N.; Staebler, Ralf M.; Neuman, J. Andrew; Nowak, John B.)<br/></b><br/><b>From Duplicate 2 (<i>High levels of molecular chlorine in the Arctic atmosphere</i> - Liao, Jin; Huey, L. Gregory; Liu, Zhen; Tanner, David J.; Cantrell, Chris A.; Orlando, John J.; Flocke, Frank M.; Shepson, Paul B.; Weinheimer, Andrew J.; Hall, Samuel R.; Ullmann, Kirk; Beine, Harry J.; Wang, Yuhang; Ingall, Ellery D.; Stephens, Chelsea R.; Hornbrook, Rebecca S.; Apel, Eric C.; Riemer, Daniel; Fried, Alan; Mauldin, Roy L.; Smith, James N.; Staebler, Ralf M.; Neuman, J. Andrew; Nowak, John B.)<br/></b><br/>Times Cited: 0<br/>Liao, Jin Huey, L. Gregory Liu, Zhen Tanner, David J. Cantrell, Chris A. Orlando, John J. Flocke, Frank M. Shepson, Paul B. Weinheimer, Andrew J. Hall, Samuel R. Ullmann, Kirk Beine, Harry J. Wang, Yuhang Ingall, Ellery D. Stephens, Chelsea R. Hornbrook, Rebecca S. Apel, Eric C. Riemer, Daniel Fried, Alan Mauldin, Roy L., III Smith, James N. Staebler, Ralf M. Neuman, J. Andrew Nowak, John B.},
 private_publication = {false},
 abstract = {Chlorine radicals can function as a strong atmospheric oxidant, particularly in polar regions, where levels of hydroxyl radicals are low. In the atmosphere, chlorine radicals expedite the degradation of methane and tropospheric ozone, and the oxidation of mercury to more toxic forms. Here we present direct measurements of molecular chlorine levels in the Arctic marine boundary layer in Barrow, Alaska, collected in the spring of 2009 over a six-week period using chemical ionization mass spectrometry. We report high levels of molecular chlorine, of up to 400 pptv. Concentrations peaked in the early morning and late afternoon, and fell to near-zero levels at night. Average daytime molecular chlorine levels were correlated with ozone concentrations, suggesting that sunlight and ozone are required for molecular chlorine formation. Using a time-dependent box model, we estimate that the chlorine radicals produced from the photolysis of molecular chlorine oxidized more methane than hydroxyl radicals, on average, and enhanced the abundance of short-lived peroxy radicals. Elevated hydroperoxyl radical levels, in turn, promoted the formation of hypobromous acid, which catalyses mercury oxidation and the breakdown of tropospheric ozone. We therefore suggest that molecular chlorine exerts a significant effect on the atmospheric chemistry of the Arctic. © 2014 Macmillan Publishers Limited. All rights reserved.},
 bibtype = {article},
 author = {Liao, Jin and Huey, L. Gregory and Liu, Zhen and Tanner, David J. and Cantrell, Chris A. and Orlando, John J. and Flocke, Frank M. and Shepson, Paul B. and Weinheimer, Andrew J. and Hall, Samuel R. and Ullmann, Kirk and Beine, Harry J. and Wang, Yuhang and Ingall, Ellery D. and Stephens, Chelsea R. and Hornbrook, Rebecca S. and Apel, Eric C. and Riemer, Daniel and Fried, Alan and Mauldin, Roy L. and Smith, James N. and Staebler, Ralf M. and Neuman, J. Andrew and Nowak, John B.},
 doi = {10.1038/ngeo2046},
 journal = {Nature Geoscience},
 number = {2}
}

Chlorine radicals can function as a strong atmospheric oxidant, particularly in polar regions, where levels of hydroxyl radicals are low. In the atmosphere, chlorine radicals expedite the degradation of methane and tropospheric ozone, and the oxidation of mercury to more toxic forms. Here we present direct measurements of molecular chlorine levels in the Arctic marine boundary layer in Barrow, Alaska, collected in the spring of 2009 over a six-week period using chemical ionization mass spectrometry. We report high levels of molecular chlorine, of up to 400 pptv. Concentrations peaked in the early morning and late afternoon, and fell to near-zero levels at night. Average daytime molecular chlorine levels were correlated with ozone concentrations, suggesting that sunlight and ozone are required for molecular chlorine formation. Using a time-dependent box model, we estimate that the chlorine radicals produced from the photolysis of molecular chlorine oxidized more methane than hydroxyl radicals, on average, and enhanced the abundance of short-lived peroxy radicals. Elevated hydroperoxyl radical levels, in turn, promoted the formation of hypobromous acid, which catalyses mercury oxidation and the breakdown of tropospheric ozone. We therefore suggest that molecular chlorine exerts a significant effect on the atmospheric chemistry of the Arctic. © 2014 Macmillan Publishers Limited. All rights reserved.

@article{
 title = {Atmospheric amines and ammonia measured with a chemical ionization mass spectrometer (CIMS)},
 type = {article},
 year = {2014},
 pages = {12181-12194},
 volume = {14},
 websites = {http://www.atmos-chem-phys.net/14/12181/2014/},
 publisher = {Copernicus Publications},
 id = {5fa36b4f-dfe0-3294-bb83-d448a69655f8},
 created = {2023-01-31T22:46:12.179Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:12.179Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {You2014},
 source_type = {Journal Article},
 notes = {<b>From Duplicate 1 (<i>Atmospheric amines and ammonia measured with a chemical ionization mass spectrometer (CIMS)</i> - You, Y.; Kanawade, V. P.; de Gouw, J. A.; Guenther, A. B.; Madronich, S.; Sierra-Hernandez, M R; Lawler, M.; Smith, J. N.; Takahama, S.; Ruggeri, G.; Koss, A.; Olson, K.; Baumann, K.; Weber, R. J.; Nenes, A.; Guo, H.; Edgerton, E. S.; Porcelli, L.; Brune, W. H.; Goldstein, A. H.; Lee, S. H.; Sierra-Hernández, M. R.; Lawler, M.; Smith, J. N.; Takahama, S.; Ruggeri, G.; Koss, A.; Olson, K.; Baumann, K.; Weber, R. J.; Nenes, A.; Guo, H.; Edgerton, E. S.; Porcelli, L.; Brune, W. H.; Goldstein, A. H.; Lee, S. H.; Sierra-Hernandez, M R; Lawler, M.; Smith, J. N.; Takahama, S.; Ruggeri, G.; Koss, A.; Olson, K.; Baumann, K.; Weber, R. J.; Nenes, A.; Guo, H.; Edgerton, E. S.; Porcelli, L.; Brune, W. H.; Goldstein, A. H.; Lee, S. H.)<br/></b><br/><b>From Duplicate 1 (<i>Atmospheric amines and ammonia measured with a chemical ionization mass spectrometer (CIMS)</i> - You, Y; Kanawade, V P; de Gouw, J A; Guenther, A B; Madronich, S; Sierra-Hernandez, M R; Lawler, M; Smith, J N; Takahama, S; Ruggeri, G; Koss, A; Olson, K; Baumann, K; Weber, R J; Nenes, A; Guo, H; Edgerton, E S; Porcelli, L; Brune, W H; Goldstein, A H; Lee, S H)<br/></b><br/>Times Cited: 0<br/><br/><b>From Duplicate 2 (<i>Atmospheric amines and ammonia measured with a chemical ionization mass spectrometer (CIMS)</i> - You, Y.; Kanawade, V. P.; De Gouw, J. A.; Guenther, A. B.; Madronich, S.; Sierra-Hernández, M. R.; Lawler, M.; Smith, J. N.; Takahama, S.; Ruggeri, G.; Koss, A.; Olson, K.; Baumann, K.; Weber, R. J.; Nenes, A.; Guo, H.; Edgerton, E. S.; Porcelli, L.; Brune, W. H.; Goldstein, A. H.; Lee, S. H.)<br/></b><br/>ACP<br/><br/><b>From Duplicate 3 (<i>Atmospheric amines and ammonia measured with a chemical ionization mass spectrometer (CIMS)</i> - You, Y; Kanawade, V P; de Gouw, J A; Guenther, A B; Madronich, S; Sierra-Hernandez, M R; Lawler, M; Smith, J N; Takahama, S; Ruggeri, G; Koss, A; Olson, K; Baumann, K; Weber, R J; Nenes, A; Guo, H; Edgerton, E S; Porcelli, L; Brune, W H; Goldstein, A H; Lee, S H)<br/></b><br/>Times Cited: 6 Koss, Abigail/B-5421-2015; Madronich, Sasha/D-3284-2015; Guenther, Alex/B-1617-2008; de Gouw, Joost/A-9675-2008; Manager, CSD Publications/B-2789-2015; Kanawade, Vijay/C-9848-2015 Madronich, Sasha/0000-0003-0983-1313; Guenther, Alex/0000-0001-6283-8288; de Gouw, Joost/0000-0002-0385-1826; Kanawade, Vijay/0000-0001-5611-3029 0 6 1680-7324<br/><br/><b>From Duplicate 2 (<i>Atmospheric amines and ammonia measured with a chemical ionization mass spectrometer (CIMS)</i> - You, Y.; Kanawade, V. P.; De Gouw, J. A.; Guenther, A. B.; Madronich, S.; Sierra-Hernández, M. R.; Lawler, M.; Smith, J. N.; Takahama, S.; Ruggeri, G.; Koss, A.; Olson, K.; Baumann, K.; Weber, R. J.; Nenes, A.; Guo, H.; Edgerton, E. S.; Porcelli, L.; Brune, W. H.; Goldstein, A. H.; Lee, S. H.)<br/></b><br/><b>From Duplicate 1 (<i>Atmospheric amines and ammonia measured with a chemical ionization mass spectrometer (CIMS)</i> - You, Y.; Kanawade, V. P.; De Gouw, J. A.; Guenther, A. B.; Madronich, S.; Sierra-Hernández, M. R.; Lawler, M.; Smith, J. N.; Takahama, S.; Ruggeri, G.; Koss, A.; Olson, K.; Baumann, K.; Weber, R. J.; Nenes, A.; Guo, H.; Edgerton, E. S.; Porcelli, L.; Brune, W. H.; Goldstein, A. H.; Lee, S. H.)<br/></b><br/>ACP<br/><br/><b>From Duplicate 2 (<i>Atmospheric amines and ammonia measured with a chemical ionization mass spectrometer (CIMS)</i> - You, Y.; Kanawade, V. P.; de Gouw, J. A.; Guenther, A. B.; Madronich, S.; Sierra-Hernandez, M R; Lawler, M.; Smith, J. N.; Takahama, S.; Ruggeri, G.; Koss, A.; Olson, K.; Baumann, K.; Weber, R. J.; Nenes, A.; Guo, H.; Edgerton, E. S.; Porcelli, L.; Brune, W. H.; Goldstein, A. H.; Lee, S. H.; Sierra-Hernández, M. R.; Lawler, M.; Smith, J. N.; Takahama, S.; Ruggeri, G.; Koss, A.; Olson, K.; Baumann, K.; Weber, R. J.; Nenes, A.; Guo, H.; Edgerton, E. S.; Porcelli, L.; Brune, W. H.; Goldstein, A. H.; Lee, S. H.; Sierra-Hernandez, M R; Lawler, M.; Smith, J. N.; Takahama, S.; Ruggeri, G.; Koss, A.; Olson, K.; Baumann, K.; Weber, R. J.; Nenes, A.; Guo, H.; Edgerton, E. S.; Porcelli, L.; Brune, W. H.; Goldstein, A. H.; Lee, S. H.)<br/></b><br/><b>From Duplicate 1 (<i>Atmospheric amines and ammonia measured with a chemical ionization mass spectrometer (CIMS)</i> - You, Y; Kanawade, V P; de Gouw, J A; Guenther, A B; Madronich, S; Sierra-Hernandez, M R; Lawler, M; Smith, J N; Takahama, S; Ruggeri, G; Koss, A; Olson, K; Baumann, K; Weber, R J; Nenes, A; Guo, H; Edgerton, E S; Porcelli, L; Brune, W H; Goldstein, A H; Lee, S H)<br/></b><br/>Times Cited: 0<br/><br/><b>From Duplicate 2 (<i>Atmospheric amines and ammonia measured with a chemical ionization mass spectrometer (CIMS)</i> - You, Y.; Kanawade, V. P.; De Gouw, J. A.; Guenther, A. B.; Madronich, S.; Sierra-Hernández, M. R.; Lawler, M.; Smith, J. N.; Takahama, S.; Ruggeri, G.; Koss, A.; Olson, K.; Baumann, K.; Weber, R. J.; Nenes, A.; Guo, H.; Edgerton, E. S.; Porcelli, L.; Brune, W. H.; Goldstein, A. H.; Lee, S. H.)<br/></b><br/>ACP<br/><br/><b>From Duplicate 3 (<i>Atmospheric amines and ammonia measured with a chemical ionization mass spectrometer (CIMS)</i> - You, Y; Kanawade, V P; de Gouw, J A; Guenther, A B; Madronich, S; Sierra-Hernandez, M R; Lawler, M; Smith, J N; Takahama, S; Ruggeri, G; Koss, A; Olson, K; Baumann, K; Weber, R J; Nenes, A; Guo, H; Edgerton, E S; Porcelli, L; Brune, W H; Goldstein, A H; Lee, S H)<br/></b><br/>Times Cited: 6 Koss, Abigail/B-5421-2015; Madronich, Sasha/D-3284-2015; Guenther, Alex/B-1617-2008; de Gouw, Joost/A-9675-2008; Manager, CSD Publications/B-2789-2015; Kanawade, Vijay/C-9848-2015 Madronich, Sasha/0000-0003-0983-1313; Guenther, Alex/0000-0001-6283-8288; de Gouw, Joost/0000-0002-0385-1826; Kanawade, Vijay/0000-0001-5611-3029 0 6 1680-7324},
 private_publication = {false},
 abstract = {<p>We report ambient measurements of amines and ammonia with a~fast response chemical ionization mass spectrometer (CIMS) in a southeastern US forest in Alabama and a~moderately polluted Midwestern site during the summer. In the Alabama forest, mostly C3-amines (from pptv to tens of pptv) and ammonia (up to 2 ppbv) were detected on a daily basis. C3-amines and ammonia showed similar diurnal trends and temperature and wind direction dependences, and were not associated with transported CO and SO<sub>2</sub> plumes. Consistent with temperature dependences, amine and ammonia in the gas and aerosol phases showed opposite diurnal trends, indicating gas-to-particle partitioning of amines and ammonia. Temperature dependences also imply reversible processes of amines and ammonia evaporation from soil surfaces in daytime and deposition of amines and ammonia to soil surfaces at nighttime. Various amines (C1–C6) at the pptv level were observed in the transported biomass burning plumes, showing that biomass burning can be a substantial source of amines in the Southeast US. At the moderately polluted Kent site, higher concentrations of amines (C1–C6, from pptv to tens of pptv) and ammonia (up to 6 ppbv) were detected. Diurnal variations of C1- to C3-amines and ammonia were correlated with the ambient temperature. C4- to C6-amines showed abrupt increases during the nighttime, suggesting that they were emitted from local sources. These abundant amines and ammonia may in part explain the frequent new particle formation events reported from Kent. Lower amine concentrations at the rural forested site highlight the importance of constraining anthropogenic sources of amines.</p>},
 bibtype = {article},
 author = {You, Y. and Kanawade, V. P. and De Gouw, J. A. and Guenther, A. B. and Madronich, S. and Sierra-Hernández, M. R. and Lawler, M. and Smith, J. N. and Takahama, S. and Ruggeri, G. and Koss, A. and Olson, K. and Baumann, K. and Weber, R. J. and Nenes, A. and Guo, H. and Edgerton, E. S. and Porcelli, L. and Brune, W. H. and Goldstein, A. H. and Lee, S. H. and Sierra-Hernandez, M R and Lawler, M. and Smith, J. N. and Takahama, S. and Ruggeri, G. and Koss, A. and Olson, K. and Baumann, K. and Weber, R. J. and Nenes, A. and Guo, H. and Edgerton, E. S. and Porcelli, L. and Brune, W. H. and Goldstein, A. H. and Lee, S. H. and Sierra-Hernández, M. R. and Lawler, M. and Smith, J. N. and Takahama, S. and Ruggeri, G. and Koss, A. and Olson, K. and Baumann, K. and Weber, R. J. and Nenes, A. and Guo, H. and Edgerton, E. S. and Porcelli, L. and Brune, W. H. and Goldstein, A. H. and Lee, S. H. and Sierra-Hernandez, M R and Lawler, M. and Smith, J. N. and Takahama, S. and Ruggeri, G. and Koss, A. and Olson, K. and Baumann, K. and Weber, R. J. and Nenes, A. and Guo, H. and Edgerton, E. S. and Porcelli, L. and Brune, W. H. and Goldstein, A. H. and Lee, S. H.},
 doi = {10.5194/acp-14-12181-2014},
 journal = {Atmospheric Chemistry and Physics},
 number = {22}
}

We report ambient measurements of amines and ammonia with a~fast response chemical ionization mass spectrometer (CIMS) in a southeastern US forest in Alabama and a~moderately polluted Midwestern site during the summer. In the Alabama forest, mostly C3-amines (from pptv to tens of pptv) and ammonia (up to 2 ppbv) were detected on a daily basis. C3-amines and ammonia showed similar diurnal trends and temperature and wind direction dependences, and were not associated with transported CO and SO₂ plumes. Consistent with temperature dependences, amine and ammonia in the gas and aerosol phases showed opposite diurnal trends, indicating gas-to-particle partitioning of amines and ammonia. Temperature dependences also imply reversible processes of amines and ammonia evaporation from soil surfaces in daytime and deposition of amines and ammonia to soil surfaces at nighttime. Various amines (C1–C6) at the pptv level were observed in the transported biomass burning plumes, showing that biomass burning can be a substantial source of amines in the Southeast US. At the moderately polluted Kent site, higher concentrations of amines (C1–C6, from pptv to tens of pptv) and ammonia (up to 6 ppbv) were detected. Diurnal variations of C1- to C3-amines and ammonia were correlated with the ambient temperature. C4- to C6-amines showed abrupt increases during the nighttime, suggesting that they were emitted from local sources. These abundant amines and ammonia may in part explain the frequent new particle formation events reported from Kent. Lower amine concentrations at the rural forested site highlight the importance of constraining anthropogenic sources of amines.

@article{
 title = {Worldwide data sets constrain the water vapor uptake coefficient in cloud formation},
 type = {article},
 year = {2013},
 pages = {3760-3764},
 volume = {110},
 id = {9ffc4423-f4e7-3fb5-88aa-efd96531355b},
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 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:17.296Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {false},
 hidden = {false},
 source_type = {article},
 private_publication = {false},
 bibtype = {article},
 author = {Raatikainen, Tomi and Nenes, Athanasios and Seinfeld, John H and Morales, Ricardo and Moore, Richard H and Lathem, Terry L and Lance, Sara and Padro, Luz T and Lina, Jack J and Cerully, Kate M and Bougiatioti, Aikaterini and Cozic, Julie and Ruehl, Christopher R and Chuang, Patrick Y and Anderson, Bruce E and Flagan, Richard C and Jonsson, Haflidi and Mihalopoulos, Nikos and Smith, James N},
 journal = {Proceedings of the National Academy of Sciences of the United States of America},
 number = {10}
}

@article{
 title = {Aerosol mixing state, hygroscopic growth and cloud activation efficiency during MIRAGE 2006},
 type = {article},
 year = {2013},
 pages = {5049-5062},
 volume = {13},
 websites = {http://www.atmos-chem-phys.net/13/5049/2013/},
 month = {5},
 day = {15},
 id = {cc16bb5b-7551-378e-b3fe-ce4a2182b6cf},
 created = {2019-12-30T23:08:28.430Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-11-02T20:28:32.343Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Lance2013},
 source_type = {Journal Article},
 notes = {<b>From Duplicate 1 (<i>Aerosol mixing state, hygroscopic growth and cloud activation efficiency during MIRAGE 2006</i> - Lance, S.; Raatikainen, T.; Onasch, T. B.; Worsnop, D. R.; Yu, X. Y.; Alexander, M. L.; Stolzenburg, M. R.; McMurry, P. H.; Smith, J. N.; Nenes, A.)<br/></b><br/>Lance, S. Raatikainen, T. Onasch, T. B. Worsnop, D. R. Yu, X. -Y. Alexander, M. L. Stolzenburg, M. R. McMurry, P. H. Smith, J. N. Nenes, A. Worsnop, Douglas/D-2817-2009; McMurry, Peter/A-8245-2008 Worsnop, Douglas/0000-0002-8928-8017; McMurry, Peter/0000-0003-1609-5131<br/><br/><b>From Duplicate 2 (<i>Aerosol mixing state, hygroscopic growth and cloud activation efficiency during MIRAGE 2006</i> - Lance, S; Raatikainen, T; Onasch, T B; Worsnop, D R; Yu, X Y; Alexander, M L; Stolzenburg, M R; McMurry, P H; Smith, J N; Nenes, A)<br/></b><br/>Times Cited: 2<br/>Lance, S. Raatikainen, T. Onasch, T. B. Worsnop, D. R. Yu, X. -Y. Alexander, M. L. Stolzenburg, M. R. McMurry, P. H. Smith, J. N. Nenes, A.},
 private_publication = {false},
 abstract = {Observations of aerosol hygroscopic growth and CCN activation spectra for submicron particles are reported for the T1 ground site outside of Mexico City during the MIRAGE 2006 campaign. κ-Köhler theory is used to evaluate the characteristic hygroscopicity parameter, κ*, for the CCN active aerosol population using both size-resolved HTMDA and size-resolved CCNc measurements. Organic mass fractions (forg) are evaluated from size-resolved aerosol mass spectrometer (AMS) measurements, from which predictions of the hygroscopicity parameter are compared against κ*. Strong diurnal changes in aerosol water uptake parameters and aerosol composition are observed. We find that new particle formation (NPF) events are correlated with an increased κ * and CCN-active fraction during the daytime, with greater impact on smaller particles. During NPF events, the number concentration of 40 nm particles acting as CCN at 0.51% ± 0.06% supersaturation can surpass by more than a factor of two the corresponding concentrations of 100 nm particles. We also find that at 06:00-08:00 LT throughout the campaign, fresh traffic emissions result in substantial changes to the chemical distribution of the aerosol, with on average 65% externally mixed fraction for 40 nm particles and 30% externally mixed fraction for 100 nm particles, whereas at midday nearly all particles of both sizes can be described as "internally mixede". Average activation spectra and growth facn t tor distributions are analyzed for different time periods characterizing the daytime (with and without NPF events), the early morning "rush hour" and the entire campaign. We show that κ* derived from CCNc measurements decrey a ases as a function of size during all time periods, while the s C te C mN-active fraction increases as a function of size. Size-resolved AMS measurements do not predict the observed trend for κ* versus particle size, which can be attributed to unresolved mixing state and the presence of refractory material not measured by the AMS. Measured κ* typically ranges from 0.2 to 0.35, and organics typically make up 60a - n85% of the aerosol mass in the size range studied. We show that κAMS is able to describe CCN concentrations reasonably well, provided mixing-state information is available, especially at the highest CCN concentrations. This is consistent with other CCN studies carried out in urban environments, and is partly due to the fact that the highest CCN concentrations occur during the daytime when the aerosol is internally mixed. During the early morning rush hour, however, failing to account for the aerosol mixing state results in systematic overestimation of CCN concentrations by as much as 50-100% on average. © Author(s) 2013.},
 bibtype = {article},
 author = {Lance, S. and Raatikainen, T. and Onasch, T. B. and Worsnop, D. R. and Yu, X. Y. and Alexander, M. L. and Stolzenburg, M. R. and McMurry, P. H. and Smith, J. N. and Nenes, A.},
 doi = {10.5194/acp-13-5049-2013},
 journal = {Atmospheric Chemistry and Physics},
 number = {9}
}

Observations of aerosol hygroscopic growth and CCN activation spectra for submicron particles are reported for the T1 ground site outside of Mexico City during the MIRAGE 2006 campaign. κ-Köhler theory is used to evaluate the characteristic hygroscopicity parameter, κ*, for the CCN active aerosol population using both size-resolved HTMDA and size-resolved CCNc measurements. Organic mass fractions (forg) are evaluated from size-resolved aerosol mass spectrometer (AMS) measurements, from which predictions of the hygroscopicity parameter are compared against κ*. Strong diurnal changes in aerosol water uptake parameters and aerosol composition are observed. We find that new particle formation (NPF) events are correlated with an increased κ * and CCN-active fraction during the daytime, with greater impact on smaller particles. During NPF events, the number concentration of 40 nm particles acting as CCN at 0.51% ± 0.06% supersaturation can surpass by more than a factor of two the corresponding concentrations of 100 nm particles. We also find that at 06:00-08:00 LT throughout the campaign, fresh traffic emissions result in substantial changes to the chemical distribution of the aerosol, with on average 65% externally mixed fraction for 40 nm particles and 30% externally mixed fraction for 100 nm particles, whereas at midday nearly all particles of both sizes can be described as "internally mixede". Average activation spectra and growth facn t tor distributions are analyzed for different time periods characterizing the daytime (with and without NPF events), the early morning "rush hour" and the entire campaign. We show that κ* derived from CCNc measurements decrey a ases as a function of size during all time periods, while the s C te C mN-active fraction increases as a function of size. Size-resolved AMS measurements do not predict the observed trend for κ* versus particle size, which can be attributed to unresolved mixing state and the presence of refractory material not measured by the AMS. Measured κ* typically ranges from 0.2 to 0.35, and organics typically make up 60a - n85% of the aerosol mass in the size range studied. We show that κAMS is able to describe CCN concentrations reasonably well, provided mixing-state information is available, especially at the highest CCN concentrations. This is consistent with other CCN studies carried out in urban environments, and is partly due to the fact that the highest CCN concentrations occur during the daytime when the aerosol is internally mixed. During the early morning rush hour, however, failing to account for the aerosol mixing state results in systematic overestimation of CCN concentrations by as much as 50-100% on average. © Author(s) 2013.

@article{
 title = {Dependence of particle nucleation and growth on high-molecular-weight gas-phase products during ozonolysis of α-pinene},
 type = {article},
 year = {2013},
 pages = {7631-7644},
 volume = {13},
 websites = {http://www.atmos-chem-phys.net/13/7631/2013/},
 month = {8},
 day = {8},
 id = {d7e6f392-c823-3d9d-b398-99b2c26fe883},
 created = {2019-12-30T23:08:30.729Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-11-02T20:28:32.459Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Zhao2013},
 source_type = {Journal Article},
 notes = {<b>From Duplicate 1 (<i>Dependence of particle nucleation and growth on high-molecular-weight gas-phase products during ozonolysis of alpha-pinene</i> - Zhao, J; Ortega, J; Chen, M; McMurry, P H; Smith, J N)<br/></b><br/>Times Cited: 1<br/>Zhao, J. Ortega, J. Chen, M. McMurry, P. H. Smith, J. N.<br/><br/><b>From Duplicate 2 (<i>Dependence of particle nucleation and growth on high-molecular-weight gas-phase products during ozonolysis of α-pinene</i> - Zhao, J.; Ortega, J.; Chen, M.; McMurry, P. H.; Smith, J. N.)<br/></b><br/>Zhao, J. Ortega, J. Chen, M. McMurry, P. H. Smith, J. N.<br/><br/><b>From Duplicate 3 (<i>Dependence of particle nucleation and growth on high-molecular-weight gas-phase products during ozonolysis of α-pinene</i> - Zhao, J.; Ortega, J.; Chen, M.; McMurry, P. H.; Smith, J. N.)<br/></b><br/>Times Cited: 8},
 private_publication = {false},
 abstract = {We report the first time-dependent measurements of high-molecular-weight (up to 700 amu) gas-phase oxidation products from α-pinene ozonolysis in an aerosol chamber under dry and low-NOx conditions. Measurements of products having mole fractions ranging from 10&minus;14 to 10&minus;11 were carried out with a chemical ionization mass spectrometer (the Cluster CIMS). Most products that were correlated with number concentrations of the smallest particles measured (10-20 nm) had molecular weights in the 430-560 amu range. Those products are proposed to be likely responsible for the initial nuclei formation and the early growth of the freshly nucleated particles based on their high molecular weights and chemical identities, both of which suggest low-volatility compounds. Another group of oxidation products in the lower mass range of 140-380 amu was well correlated with particles larger than 20 nm. We postulate that those products contributed to the later growth of particles (i.e., larger than 20 nm in diameter). Although particle nucleation in this study was primarily due to condensation of oxidation products from α-pinene ozonolysis, the involvement of residual sulfuric acid vapor in particle nucleation cannot be totally excluded. © Author(s) 2013.},
 bibtype = {article},
 author = {Zhao, J. and Ortega, J. and Chen, M. and McMurry, P. H. and Smith, J. N.},
 doi = {10.5194/acp-13-7631-2013},
 journal = {Atmospheric Chemistry and Physics},
 number = {15}
}

We report the first time-dependent measurements of high-molecular-weight (up to 700 amu) gas-phase oxidation products from α-pinene ozonolysis in an aerosol chamber under dry and low-NOx conditions. Measurements of products having mole fractions ranging from 10−14 to 10−11 were carried out with a chemical ionization mass spectrometer (the Cluster CIMS). Most products that were correlated with number concentrations of the smallest particles measured (10-20 nm) had molecular weights in the 430-560 amu range. Those products are proposed to be likely responsible for the initial nuclei formation and the early growth of the freshly nucleated particles based on their high molecular weights and chemical identities, both of which suggest low-volatility compounds. Another group of oxidation products in the lower mass range of 140-380 amu was well correlated with particles larger than 20 nm. We postulate that those products contributed to the later growth of particles (i.e., larger than 20 nm in diameter). Although particle nucleation in this study was primarily due to condensation of oxidation products from α-pinene ozonolysis, the involvement of residual sulfuric acid vapor in particle nucleation cannot be totally excluded. © Author(s) 2013.

@article{
 title = {Direct observations of atmospheric aerosol nucleation},
 type = {article},
 year = {2013},
 keywords = {amine,climate,clusters,growth,nanoparticles,particle formation,rates,smear-ii,sulfuric-acid,water},
 pages = {943-946},
 volume = {339},
 websites = {http://www.sciencemag.org/content/339/6122/943.abstract},
 id = {9a29d5f7-067a-354d-b81a-fc296ed6999b},
 created = {2020-08-21T23:09:04.152Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-08-21T23:09:04.152Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Kulmala2013},
 source_type = {Journal Article},
 language = {English},
 notes = {<b>From Duplicate 1 (<i>Direct observations of atmospheric aerosol nucleation</i> - Kulmala, Markku; Kontkanen, Jenni; Junninen, Heikki; Lehtipalo, Katrianne; Manninen, Hanna E.; Nieminen, Tuomo; Petäjä, Tuukka; Sipilä, Mikko; Schobesberger, Siegfried; Rantala, Pekka; Franchin, Alessandro; Jokinen, Tuija; Järvinen, Emma; Äijälä, Mikko; Kangasluoma, Juha; Hakala, Jani; Aalto, Pasi P.; Paasonen, Pauli; Mikkilä, Jyri; Vanhanen, Joonas; Aalto, Juho; Hakola, Hannele; Makkonen, Ulla; Ruuskanen, Taina; Mauldin, Roy L.; Duplissy, Jonathan; Vehkamäki, Hanna; Bäck, Jaana; Kortelainen, Aki; Riipinen, Ilona; Kurtén, Theo; Johnston, Murray V.; Smith, James N.; Ehn, Mikael; Mentel, Thomas F.; Lehtinen, Kari E.J.; Laaksonen, Ari; Kerminen, Veli Matti; Worsnop, Douglas R.)<br/></b><br/>Times Cited: 123<br/><br/><b>From Duplicate 2 (<i>Direct observations of atmospheric aerosol nucleation</i> - Kulmala, Markku; Kontkanen, Jenni; Junninen, Heikki; Lehtipalo, Katrianne; Manninen, Hanna E.; Nieminen, Tuomo; Petäjä, Tuukka; Sipilä, Mikko; Schobesberger, Siegfried; Rantala, Pekka; Franchin, Alessandro; Jokinen, Tuija; Järvinen, Emma; Äijälä, Mikko; Kangasluoma, Juha; Hakala, Jani; Aalto, Pasi P.; Paasonen, Pauli; Mikkilä, Jyri; Vanhanen, Joonas; Aalto, Juho; Hakola, Hannele; Makkonen, Ulla; Ruuskanen, Taina; Mauldin, Roy L.; Duplissy, Jonathan; Vehkamäki, Hanna; Bäck, Jaana; Kortelainen, Aki; Riipinen, Ilona; Kurtén, Theo; Johnston, Murray V.; Smith, James N.; Ehn, Mikael; Mentel, Thomas F.; Lehtinen, Kari E.J.; Laaksonen, Ari; Kerminen, Veli Matti; Worsnop, Douglas R.)<br/></b><br/><b>From Duplicate 2 (<i>Direct Observations of Atmospheric Aerosol Nucleation</i> - Kulmala, M; Kontkanen, J; Junninen, H; Lehtipalo, K; Manninen, H E; Nieminen, T; Petaja, T; Sipila, M; Schobesberger, S; Rantala, P; Franchin, A; Jokinen, T; Jarvinen, E; Aijala, M; Kangasluoma, J; Hakala, J; Aalto, P P; Paasonen, P; Mikkila, J; Vanhanen, J; Aalto, J; Hakola, H; Makkonen, U; Ruuskanen, T; Mauldin, R L; Duplissy, J; Vehkamaki, H; Back, J; Kortelainen, A; Riipinen, I; Kurten, T; Johnston, M V; Smith, J N; Ehn, M; Mentel, T F; Lehtinen, K E J; Laaksonen, A; Kerminen, V M; Worsnop, D R)<br/></b><br/>Times Cited: 41<br/>Kulmala, Markku Kontkanen, Jenni Junninen, Heikki Lehtipalo, Katrianne Manninen, Hanna E. Nieminen, Tuomo Petaja, Tuukka Sipila, Mikko Schobesberger, Siegfried Rantala, Pekka Franchin, Alessandro Jokinen, Tuija Jarvinen, Emma Aijala, Mikko Kangasluoma, Juha Hakala, Jani Aalto, Pasi P. Paasonen, Pauli Mikkila, Jyri Vanhanen, Joonas Aalto, Juho Hakola, Hannele Makkonen, Ulla Ruuskanen, Taina Mauldin, Roy L., III Duplissy, Jonathan Vehkamaki, Hanna Back, Jaana Kortelainen, Aki Riipinen, Ilona Kurten, Theo Johnston, Murray V. Smith, James N. Ehn, Mikael Mentel, Thomas F. Lehtinen, Kari E. J. Laaksonen, Ari Kerminen, Veli-Matti Worsnop, Douglas R.<br/><br/><b>From Duplicate 3 (<i>Direct Observations of Atmospheric Aerosol Nucleation</i> - Kulmala, M; Kontkanen, J; Junninen, H; Lehtipalo, K; Manninen, H E; Nieminen, T; Petaja, T; Sipila, M; Schobesberger, S; Rantala, P; Franchin, A; Jokinen, T; Jarvinen, E; Aijala, M; Kangasluoma, J; Hakala, J; Aalto, P P; Paasonen, P; Mikkila, J; Vanhanen, J; Aalto, J; Hakola, H; Makkonen, U; Ruuskanen, T; Mauldin, R L; Duplissy, J; Vehkamaki, H; Back, J; Kortelainen, A; Riipinen, I; Kurten, T; Johnston, M V; Smith, J N; Ehn, M; Mentel, T F; Lehtinen, K E J; Laaksonen, A; Kerminen, V M; Worsnop, D R)<br/></b><br/>092UX<br/>Times Cited:1<br/>Cited References Count:31<br/><br/><b>From Duplicate 4 (<i>Direct observations of atmospheric aerosol nucleation</i> - Kulmala, Markku; Kontkanen, Jenni; Junninen, Heikki; Lehtipalo, Katrianne; Manninen, Hanna E.; Nieminen, Tuomo; Petäjä, Tuukka; Sipilä, Mikko; Schobesberger, Siegfried; Rantala, Pekka; Franchin, Alessandro; Jokinen, Tuija; Järvinen, Emma; Äijälä, Mikko; Kangasluoma, Juha; Hakala, Jani; Aalto, Pasi P.; Paasonen, Pauli; Mikkilä, Jyri; Vanhanen, Joonas; Aalto, Juho; Hakola, Hannele; Makkonen, Ulla; Ruuskanen, Taina; Mauldin, Roy L.; Duplissy, Jonathan; Vehkamäki, Hanna; Bäck, Jaana; Kortelainen, Aki; Riipinen, Ilona; Kurtén, Theo; Johnston, Murray V.; Smith, James N.; Ehn, Mikael; Mentel, Thomas F.; Lehtinen, Kari E.J.; Laaksonen, Ari; Kerminen, Veli Matti; Worsnop, Douglas R.)<br/></b><br/>Times Cited: 123},
 private_publication = {false},
 abstract = {Atmospheric nucleation is the dominant source of aerosol particles in the global atmosphere and an important player in aerosol climatic effects. The key steps of this process occur in the sub-2-nanometer (nm) size range, in which direct size-segregated observations have not been possible until very recently. Here, we present detailed observations of atmospheric nanoparticles and clusters down to 1-nm mobility diameter. We identified three separate size regimes below 2-nm diameter that build up a physically, chemically, and dynamically consistent framework on atmospheric nucleation - more specifically, aerosol formation via neutral pathways. Our findings emphasize the important role of organic compounds in atmospheric aerosol formation, subsequent aerosol growth, radiative forcing and associated feedbacks between biogenic emissions, clouds, and climate.},
 bibtype = {article},
 author = {Kulmala, Markku and Kontkanen, Jenni and Junninen, Heikki and Lehtipalo, Katrianne and Manninen, Hanna E. and Nieminen, Tuomo and Petäjä, Tuukka and Sipilä, Mikko and Schobesberger, Siegfried and Rantala, Pekka and Franchin, Alessandro and Jokinen, Tuija and Järvinen, Emma and Äijälä, Mikko and Kangasluoma, Juha and Hakala, Jani and Aalto, Pasi P. and Paasonen, Pauli and Mikkilä, Jyri and Vanhanen, Joonas and Aalto, Juho and Hakola, Hannele and Makkonen, Ulla and Ruuskanen, Taina and Mauldin, Roy L. and Duplissy, Jonathan and Vehkamäki, Hanna and Bäck, Jaana and Kortelainen, Aki and Riipinen, Ilona and Kurtén, Theo and Johnston, Murray V. and Smith, James N. and Ehn, Mikael and Mentel, Thomas F. and Lehtinen, Kari E.J. and Laaksonen, Ari and Kerminen, Veli Matti and Worsnop, Douglas R.},
 doi = {10.1126/science.1227385},
 journal = {Science},
 number = {6122}
}

Atmospheric nucleation is the dominant source of aerosol particles in the global atmosphere and an important player in aerosol climatic effects. The key steps of this process occur in the sub-2-nanometer (nm) size range, in which direct size-segregated observations have not been possible until very recently. Here, we present detailed observations of atmospheric nanoparticles and clusters down to 1-nm mobility diameter. We identified three separate size regimes below 2-nm diameter that build up a physically, chemically, and dynamically consistent framework on atmospheric nucleation - more specifically, aerosol formation via neutral pathways. Our findings emphasize the important role of organic compounds in atmospheric aerosol formation, subsequent aerosol growth, radiative forcing and associated feedbacks between biogenic emissions, clouds, and climate.

@article{
 title = {Quantitative and time-resolved nanoparticle composition measurements during new particle formation},
 type = {article},
 year = {2013},
 keywords = {aerosol mass-spectrometer,ammonia,atmospheric nucleation,chemical-composition,clusters,experimental setup,growth-rates,nitrate,organic-acids,sulfuric-acid},
 pages = {25-43},
 volume = {165},
 websites = {http://xlink.rsc.org/?DOI=c3fd00039g},
 id = {5e7b019c-6ea3-3f0d-8fd6-3353fea2293b},
 created = {2023-01-31T22:46:06.425Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:06.425Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Bzdek2013},
 source_type = {article},
 language = {English},
 notes = {<b>From Duplicate 2 (<i>Quantitative and time-resolved nanoparticle composition measurements during new particle formation</i> - Bzdek, Bryan R.; Horan, Andrew J.; Ross Pennington, M.; Depalma, Joseph W.; Zhao, Jun; Jen, Coty N.; Hanson, David R.; Smith, James N.; McMurry, Peter H.; Johnston, Murray V.)<br/></b><br/><b>From Duplicate 3 (<i>Quantitative and time-resolved nanoparticle composition measurements during new particle formation</i> - Bzdek, B R; Horan, A J; Pennington, M R; DePalma, J W; Zhao, J; Jen, C N; Hanson, D R; Smith, J N; McMurry, P H; Johnston, M V)<br/></b><br/>ISI Document Delivery No.: 280ZF<br/>Times Cited: 2<br/>Cited Reference Count: 73<br/>Bzdek, Bryan R. Horan, Andrew J. Pennington, M. Ross DePalma, Joseph W. Zhao, Jun Jen, Coty N. Hanson, David R. Smith, James N. McMurry, Peter H. Johnston, Murray V.<br/>National Science Foundation [AGS1205304]; STAR Graduate Fellowship by the U.S. Environmental Protection Agency (EPA). [FP-91731501]; Finnish Academy [251007]; U.S. Department of Energy [DE-SC0006861]<br/>This work was supported by the National Science Foundation under grant no. AGS1205304. B. R. B. acknowledges a STAR Graduate Fellowship (FP-91731501) awarded by the U.S. Environmental Protection Agency (EPA). The views expressed in this publication are solely those of the authors, and the U. S. EPA does not endorse any products or commercial services mentioned in this publication. Meteorological and ultra. ne particle monitor measurements were performed by the Delaware Department of Natural Resources and Environmental Control. The authors thank Julia Eichhorn for assistance in the acquisition and analysis of NAMS data. The National Center for Atmospheric Research is sponsored by the National Science Foundation. J.N.S. acknowledges funding from the Finnish Academy Grant No. 251007 and U.S. Department of Energy grant no. DE-SC0006861. The authors thank George W. Luther III for providing access to the Lewes site and facilitating the measurement campaign.<br/>Royal soc chemistry<br/>Cambridge<br/><br/><b>From Duplicate 4 (<i>Quantitative and time-resolved nanoparticle composition measurements during new particle formation</i> - Bzdek, Bryan R; Horan, Andrew J; Pennington, M Ross; DePalma, Joseph W; Zhao, Jun; Jen, Coty N; Hanson, David R; Smith, James N; McMurry, Peter H; Johnston, Murray V)<br/></b><br/>Times Cited: 6},
 private_publication = {false},
 abstract = {The chemical composition of 20 nm diameter particles was measured with the Nano Aerosol Mass Spectrometer (NAMS) in a rural/coastal environment during days when new particle formation (NPF) occurred and days when NPF did not occur. NAMS provides a quantitative measure of nanoparticle elemental composition with high time resolution. These measurements show that nanoparticle chemical composition is dynamic on both types of days and that changes in nanoparticle chemical composition do not necessarily correlate with changes in aerosol mass or number concentration. On NPF days, NAMS can distinguish between elements associated with particle formation and early mass growth from those associated with later mass growth. In the early stage of NPF, the particle phase sulphur mole fraction (S) increases simultaneously with the increase in gas phase sulphuric acid. This composition change occurs before the mode diameter has grown into the NAMS-measured size range and is quantitatively described by sulphuric acid condensation. The nitrogen mole fraction (N) also increases during this time period. The N/S mole ratio is approximately 2, indicating that particulate sulphate is fully neutralized. As the mode diameter passes into and through the NAMS-measured size range, N increases at a faster rate than S (N/S mole ratio increases above 2), indicating that a separate, nitrogen-based growth process exists, possibly involving aminium salts, inorganic nitrate and/or organonitrates. Carbonaceous matter is the most abundant component (∼50% by mass) of the growing nanoparticles, but it is the inorganic species that are preferentially enhanced during NPF relative to other times of day. Concurrent measurements of cloud condensation nucleation activity during NPF events suggest that these newly formed particles are hygroscopic. Nanoparticle composition on non-NPF days also shifts toward a more inorganic composition during the daytime, but the chemical species are different from NPF days and the particles are less hygroscopic. Incorporation of S into growing nanoparticles is adequately explained by existing models, but currently no models exist to satisfactorily explain incorporation of nitrogen-containing species or carbonaceous matter. © 2014 The Royal Society of Chemistry.},
 bibtype = {article},
 author = {Bzdek, Bryan R. and Horan, Andrew J. and Ross Pennington, M. and Depalma, Joseph W. and Zhao, Jun and Jen, Coty N. and Hanson, David R. and Smith, James N. and McMurry, Peter H. and Johnston, Murray V.},
 doi = {10.1039/c3fd00039g},
 journal = {Faraday Discussions}
}

The chemical composition of 20 nm diameter particles was measured with the Nano Aerosol Mass Spectrometer (NAMS) in a rural/coastal environment during days when new particle formation (NPF) occurred and days when NPF did not occur. NAMS provides a quantitative measure of nanoparticle elemental composition with high time resolution. These measurements show that nanoparticle chemical composition is dynamic on both types of days and that changes in nanoparticle chemical composition do not necessarily correlate with changes in aerosol mass or number concentration. On NPF days, NAMS can distinguish between elements associated with particle formation and early mass growth from those associated with later mass growth. In the early stage of NPF, the particle phase sulphur mole fraction (S) increases simultaneously with the increase in gas phase sulphuric acid. This composition change occurs before the mode diameter has grown into the NAMS-measured size range and is quantitatively described by sulphuric acid condensation. The nitrogen mole fraction (N) also increases during this time period. The N/S mole ratio is approximately 2, indicating that particulate sulphate is fully neutralized. As the mode diameter passes into and through the NAMS-measured size range, N increases at a faster rate than S (N/S mole ratio increases above 2), indicating that a separate, nitrogen-based growth process exists, possibly involving aminium salts, inorganic nitrate and/or organonitrates. Carbonaceous matter is the most abundant component (∼50% by mass) of the growing nanoparticles, but it is the inorganic species that are preferentially enhanced during NPF relative to other times of day. Concurrent measurements of cloud condensation nucleation activity during NPF events suggest that these newly formed particles are hygroscopic. Nanoparticle composition on non-NPF days also shifts toward a more inorganic composition during the daytime, but the chemical species are different from NPF days and the particles are less hygroscopic. Incorporation of S into growing nanoparticles is adequately explained by existing models, but currently no models exist to satisfactorily explain incorporation of nitrogen-containing species or carbonaceous matter. © 2014 The Royal Society of Chemistry.

@article{
 title = {Aerosol Chemical Composition in Cloud Events by High Resolution Time-of-Flight Aerosol Mass Spectrometry},
 type = {article},
 year = {2013},
 pages = {2645-2653},
 volume = {47},
 id = {a64f9476-c5ef-31af-b795-83fa5eb7bf51},
 created = {2023-01-31T22:46:07.627Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:07.627Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Hao2013a},
 source_type = {article},
 notes = {<b>From Duplicate 1 (<i>Aerosol Chemical Composition in Cloud Events by High Resolution Time-of-Flight Aerosol Mass Spectrometry</i> - Hao, L Q; Romakkaniemi, S; Kortelainen, A; Jaatinen, A; Portin, H; Miettinen, P; Komppula, M; Leskinen, A; Virtanen, A; Smith, J N; Sueper, D; Worsnop, D R; Lehtinen, K E J; Laaksonen, A)<br/></b><br/>Times Cited: 2<br/>Hao, Liqing Romakkaniemi, Sami Kortelainen, Aki Jaatinen, Antti Portin, Harri Miettinen, Pasi Komppula, Mika Leskinen, Ari Virtanen, Annele Smith, James N. Sueper, Donna Worsnop, Douglas R. Lehtinen, Karl E. J. Laaksonen, Ari},
 private_publication = {false},
 abstract = {This study presents results of direct observations of aerosol chemical composition in clouds. A high-resolution time-of-flight aerosol mass spectrometer was used to make measurements of cloud interstitial particles (INT) and mixed cloud interstitial and droplet residual particles (TOT). The differences between these two are the cloud droplet residuals (RES). Positive matrix factorization analysis of high-resolution mass spectral data sets and theoretical calculations were performed to yield distributions of chemical composition of the INT and RES particles. We observed that less oxidized hydrocarbon-like organic aerosols (HOA) were mainly distributed into the INT particles, whereas more oxidized low-volatile oxygenated OA (LVOOA) mainly in the RES particles. Nitrates existed as organic nitrate and in chemical form of NH4NO3. Organic nitrates nitrates in the INT particles, in clear contrast to 26% in the RES particles. Meanwhile, sulfates coexist in forms of acidic NH4HSO4 and neutralized (NH4)(2)SO4. Acidic sulfate made up 64.8% of total sulfates in the INT particles, much higher than 10.7% in the RES particles. The results indicate a possible joint effect of activation ability of aerosol particles, cloud processing, and particle size effects on cloud formation.},
 bibtype = {article},
 author = {Hao, Liqing Q and Romakkaniemi, Sami and Kortelainen, Aki and Jaatinen, Antti and Portin, Harri and Miettinen, Pasi and Komppula, Mika and Leskinen, Ari and Virtanen, Annele and Smith, James N. and Sueper, Donna and Worsnop, Douglas R. and Lehtinen, Kari E.J. J and Laaksonen, Ari},
 doi = {10.1021/es302889w},
 journal = {Environmental Science and Technology},
 number = {6}
}

This study presents results of direct observations of aerosol chemical composition in clouds. A high-resolution time-of-flight aerosol mass spectrometer was used to make measurements of cloud interstitial particles (INT) and mixed cloud interstitial and droplet residual particles (TOT). The differences between these two are the cloud droplet residuals (RES). Positive matrix factorization analysis of high-resolution mass spectral data sets and theoretical calculations were performed to yield distributions of chemical composition of the INT and RES particles. We observed that less oxidized hydrocarbon-like organic aerosols (HOA) were mainly distributed into the INT particles, whereas more oxidized low-volatile oxygenated OA (LVOOA) mainly in the RES particles. Nitrates existed as organic nitrate and in chemical form of NH4NO3. Organic nitrates nitrates in the INT particles, in clear contrast to 26% in the RES particles. Meanwhile, sulfates coexist in forms of acidic NH4HSO4 and neutralized (NH4)(2)SO4. Acidic sulfate made up 64.8% of total sulfates in the INT particles, much higher than 10.7% in the RES particles. The results indicate a possible joint effect of activation ability of aerosol particles, cloud processing, and particle size effects on cloud formation.

@article{
 title = {Identification and quantification of particle growth channels during new particle formation},
 type = {article},
 year = {2013},
 pages = {10215-10225},
 volume = {13},
 websites = {http://www.atmos-chem-phys.net/13/10215/2013/},
 month = {10},
 day = {17},
 id = {c833ef39-2da7-30bd-a3bd-29e8cf864d3f},
 created = {2023-01-31T22:46:09.047Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:09.047Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Pennington2013},
 source_type = {Journal Article},
 notes = {<b>From Duplicate 1 (<i>Identification and quantification of particle growth channels during new particle formation</i> - Pennington, M. R.; Bzdek, B. R.; Depalma, J. W.; Smith, J. N.; Kortelainen, A. M.; Hildebrandt Ruiz, L.; Petäjä, T.; Kulmala, M.; Worsnop, D. R.; Johnston, M. V.)<br/></b><br/>Times Cited: 4<br/><br/><b>From Duplicate 2 (<i>Identification and quantification of particle growth channels during new particle formation</i> - Pennington, M. R.; Bzdek, B. R.; Depalma, J. W.; Smith, J. N.; Kortelainen, A. M.; Hildebrandt Ruiz, L.; Petäjä, T.; Kulmala, M.; Worsnop, D. R.; Johnston, M. V.)<br/></b><br/><b>From Duplicate 1 (<i>Identification and quantification of particle growth channels during new particle formation</i> - Pennington, M. R.; Bzdek, B. R.; Depalma, J. W.; Smith, J. N.; Kortelainen, A. M.; Ruiz, L Hildebrandt; Petaja, T; Kulmala, M.; Worsnop, D. R.; Johnston, M. V.; Hildebrandt Ruiz, L.; Petäjä, T.; Kulmala, M.; Worsnop, D. R.; Johnston, M. V.)<br/></b><br/><b>From Duplicate 1 (<i>Identification and quantification of particle growth channels during new particle formation</i> - Pennington, M. R.; Bzdek, B. R.; Depalma, J. W.; Smith, J. N.; Kortelainen, A. M.; Hildebrandt Ruiz, L.; Petäjä, T.; Kulmala, M.; Worsnop, D. R.; Johnston, M. V.)<br/></b><br/>Times Cited: 4},
 private_publication = {false},
 abstract = {Atmospheric new particle formation (NPF) is a key source of ambient ultrafine particles that may contribute substantially to the global production of cloud condensation nuclei (CCN). While NPF is driven by atmospheric nucleation, its impact on CCN concentration depends strongly on atmospheric growth mechanisms since the growth rate must exceed the loss rate due to scavenging in order for the particles to reach the CCN size range. In this work, chemical composition measurements of 20 nm diameter particles during NPF in Hyytiälä, Finland, in March-April 2011 permit identification and quantitative assessment of important growth channels. In this work we show the following: (A) sulfuric acid, a key species associated with atmospheric nucleation, accounts for less than half of particle mass growth during this time period; (B) the sulfate content of a growing particle during NPF is quantitatively explained by condensation of gas-phase sulfuric acid molecules (i.e., sulfuric acid uptake is collision-limited); (C) sulfuric acid condensation substantially impacts the chemical composition of preexisting nanoparticles before new particles have grown to a size sufficient to be measured; (D) ammonium and sulfate concentrations are highly correlated, indicating that ammonia uptake is driven by sulfuric acid uptake; (E) sulfate neutralization by ammonium does not reach the predicted thermodynamic end point, suggesting that a barrier exists for ammonia uptake; (F) carbonaceous matter accounts for more than half of the particle mass growth, and its oxygen-to-carbon ratio (∼ 0.5) is characteristic of freshly formed secondary organic aerosol; and (G) differences in the overall growth rate from one formation event to another are caused by variations in the growth rates of all major chemical species, not just one individual species. © Author(s) 2013.},
 bibtype = {article},
 author = {Pennington, M. R. and Bzdek, B. R. and Depalma, J. W. and Smith, J. N. and Kortelainen, A. M. and Hildebrandt Ruiz, L. and Petäjä, T. and Kulmala, M. and Worsnop, D. R. and Johnston, M. V.},
 doi = {10.5194/acp-13-10215-2013},
 journal = {Atmospheric Chemistry and Physics},
 number = {20}
}

Atmospheric new particle formation (NPF) is a key source of ambient ultrafine particles that may contribute substantially to the global production of cloud condensation nuclei (CCN). While NPF is driven by atmospheric nucleation, its impact on CCN concentration depends strongly on atmospheric growth mechanisms since the growth rate must exceed the loss rate due to scavenging in order for the particles to reach the CCN size range. In this work, chemical composition measurements of 20 nm diameter particles during NPF in Hyytiälä, Finland, in March-April 2011 permit identification and quantitative assessment of important growth channels. In this work we show the following: (A) sulfuric acid, a key species associated with atmospheric nucleation, accounts for less than half of particle mass growth during this time period; (B) the sulfate content of a growing particle during NPF is quantitatively explained by condensation of gas-phase sulfuric acid molecules (i.e., sulfuric acid uptake is collision-limited); (C) sulfuric acid condensation substantially impacts the chemical composition of preexisting nanoparticles before new particles have grown to a size sufficient to be measured; (D) ammonium and sulfate concentrations are highly correlated, indicating that ammonia uptake is driven by sulfuric acid uptake; (E) sulfate neutralization by ammonium does not reach the predicted thermodynamic end point, suggesting that a barrier exists for ammonia uptake; (F) carbonaceous matter accounts for more than half of the particle mass growth, and its oxygen-to-carbon ratio (∼ 0.5) is characteristic of freshly formed secondary organic aerosol; and (G) differences in the overall growth rate from one formation event to another are caused by variations in the growth rates of all major chemical species, not just one individual species. © Author(s) 2013.

@article{
 title = {Identification of the biogenic compounds responsible for size-dependent nanoparticle growth},
 type = {article},
 year = {2012},
 keywords = {alpha-pinene,atmospheric particles,mcm v3,nucleation,particle chemical-composition,rates,secondary organic aerosol,sulfuric-acid},
 volume = {39},
 id = {3ebe3255-7205-3351-9eb4-a71ecdd76714},
 created = {2016-07-07T17:21:19.000Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-08-21T23:00:47.881Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Winkler2012},
 source_type = {Journal Article},
 language = {English},
 notes = {032DC<br/>Times Cited:0<br/>Cited References Count:21},
 private_publication = {false},
 abstract = {[1] The probability that freshly nucleated nanoparticles can survive to become cloud condensation nuclei is highly sensitive to particle growth rates. Much of the growth of newly formed ambient nanoparticles can be attributed to oxidized organic vapors originating from biogenic precursor gases. In this study we investigated the chemical composition of size-selected biogenic nanoparticles in the size range from 10 to 40 nm. Particles were formed in a flow tube reactor by ozonolysis of a-pinene and analyzed with a Thermal Desorption Chemical Ionization Mass Spectrometer. While we found similar composition in 10 and 20 nm particles, the relative amounts of individual species varied significantly when compared to 40 nm particles. Smaller particles (10 and 20 nm) were characterized by enhancements in carboxylic acids and larger particles (40 nm) showed higher concentrations of carbonyl-containing compounds and low molecular weight organic acids. This composition change from smaller to larger size particles reflects a vapor pressure increase of the condensing vapors by 1-2 orders of magnitude indicating that the Kelvin effect plays a decisive role in the growth of biogenic nanoparticles. © 2012. American Geophysical Union. All Rights Reserved.},
 bibtype = {article},
 author = {Winkler, Paul M. and Ortega, John and Karl, Thomas and Cappellin, Luca and Friedli, Hans R. and Barsanti, Kelley and McMurry, Peter H. and Smith, James N.},
 doi = {10.1029/2012GL053253},
 journal = {Geophysical Research Letters},
 number = {20}
}

[1] The probability that freshly nucleated nanoparticles can survive to become cloud condensation nuclei is highly sensitive to particle growth rates. Much of the growth of newly formed ambient nanoparticles can be attributed to oxidized organic vapors originating from biogenic precursor gases. In this study we investigated the chemical composition of size-selected biogenic nanoparticles in the size range from 10 to 40 nm. Particles were formed in a flow tube reactor by ozonolysis of a-pinene and analyzed with a Thermal Desorption Chemical Ionization Mass Spectrometer. While we found similar composition in 10 and 20 nm particles, the relative amounts of individual species varied significantly when compared to 40 nm particles. Smaller particles (10 and 20 nm) were characterized by enhancements in carboxylic acids and larger particles (40 nm) showed higher concentrations of carbonyl-containing compounds and low molecular weight organic acids. This composition change from smaller to larger size particles reflects a vapor pressure increase of the condensing vapors by 1-2 orders of magnitude indicating that the Kelvin effect plays a decisive role in the growth of biogenic nanoparticles. © 2012. American Geophysical Union. All Rights Reserved.

@article{
 title = {Identification of the biogenic compounds responsible for size-dependent nanoparticle growth},
 type = {article},
 year = {2012},
 volume = {39},
 id = {ed87ba45-39ff-3907-9aaa-2c89975b339c},
 created = {2017-04-12T23:44:41.453Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:24.343Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {false},
 hidden = {false},
 source_type = {article},
 notes = {Times Cited: 0 Winkler, Paul M. Ortega, John Karl, Thomas Cappellin, Luca Friedli, Hans R. Barsanti, Kelley McMurry, Peter H. Smith, James N.},
 private_publication = {false},
 abstract = {The probability that freshly nucleated nanoparticles can survive to become cloud condensation nuclei is highly sensitive to particle growth rates. Much of the growth of newly formed ambient nanoparticles can be attributed to oxidized organic vapors originating from biogenic precursor gases. In this study we investigated the chemical composition of size-selected biogenic nanoparticles in the size range from 10 to 40 nm. Particles were formed in a flow tube reactor by ozonolysis of a-pinene and analyzed with a Thermal Desorption Chemical Ionization Mass Spectrometer. While we found similar composition in 10 and 20 nm particles, the relative amounts of individual species varied significantly when compared to 40 nm particles. Smaller particles (10 and 20 nm) were characterized by enhancements in carboxylic acids and larger particles (40 nm) showed higher concentrations of carbonyl-containing compounds and low molecular weight organic acids. This composition change from smaller to larger size particles reflects a vapor pressure increase of the condensing vapors by 1-2 orders of magnitude indicating that the Kelvin effect plays a decisive role in the growth of biogenic nanoparticles. Citation: Winkler, P. M., J. Ortega, T. Karl, L. Cappellin, H. R. Friedli, K. Barsanti, P. H. McMurry, and J. N. Smith (2012), Identification of the biogenic compounds responsible for size-dependent nanoparticle growth, Geophys. Res. Lett., 39, L20815, doi:10.1029/2012GL053253.},
 bibtype = {article},
 author = {Winkler, P M and Ortega, J and Karl, T and Cappellin, L and Friedli, H R and Barsanti, K and McMurry, P H and Smith, J N},
 journal = {Geophysical Research Letters}
}

The probability that freshly nucleated nanoparticles can survive to become cloud condensation nuclei is highly sensitive to particle growth rates. Much of the growth of newly formed ambient nanoparticles can be attributed to oxidized organic vapors originating from biogenic precursor gases. In this study we investigated the chemical composition of size-selected biogenic nanoparticles in the size range from 10 to 40 nm. Particles were formed in a flow tube reactor by ozonolysis of a-pinene and analyzed with a Thermal Desorption Chemical Ionization Mass Spectrometer. While we found similar composition in 10 and 20 nm particles, the relative amounts of individual species varied significantly when compared to 40 nm particles. Smaller particles (10 and 20 nm) were characterized by enhancements in carboxylic acids and larger particles (40 nm) showed higher concentrations of carbonyl-containing compounds and low molecular weight organic acids. This composition change from smaller to larger size particles reflects a vapor pressure increase of the condensing vapors by 1-2 orders of magnitude indicating that the Kelvin effect plays a decisive role in the growth of biogenic nanoparticles. Citation: Winkler, P. M., J. Ortega, T. Karl, L. Cappellin, H. R. Friedli, K. Barsanti, P. H. McMurry, and J. N. Smith (2012), Identification of the biogenic compounds responsible for size-dependent nanoparticle growth, Geophys. Res. Lett., 39, L20815, doi:10.1029/2012GL053253.

@article{
 title = {On the formation of sulphuric acid – Amine clusters in varying atmospheric conditions and its influence on atmospheric new particle formation},
 type = {article},
 year = {2012},
 pages = {9113-9133},
 volume = {12},
 websites = {http://www.atmos-chem-phys.net/12/9113/2012/},
 id = {a240d74d-256a-3443-8fd9-380c70eb693d},
 created = {2023-01-31T22:46:05.400Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:05.400Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Paasonen2012},
 source_type = {article},
 private_publication = {false},
 abstract = {Sulphuric acid is a key component in atmo-spheric new particle formation. However, sulphuric acid alone does not form stable enough clusters to initiate par-ticle formation in atmospheric conditions. Strong bases, such as amines, have been suggested to stabilize sulphuric acid clusters and thus participate in particle formation. We modelled the formation rate of clusters with two sulphuric acid and two amine molecules (J A2B2) at varying atmo-spherically relevant conditions with respect to concentrations of sulphuric acid ([H 2 SO 4 ]), dimethylamine ([DMA]) and trimethylamine ([TMA]), temperature and relative humidity (RH). We also tested how the model results change if we assume that the clusters with two sulphuric acid and two amine molecules would act as seeds for heterogeneous nucle-ation of organic vapours (other than amines) with higher at-mospheric concentrations than sulphuric acid. The modelled formation rates J A2B2 were functions of sulphuric acid con-centration with close to quadratic dependence, which is in good agreement with atmospheric observations of the con-nection between the particle formation rate and sulphuric acid concentration. The coefficients K A2B2 connecting the cluster formation rate and sulphuric acid concentrations as J A2B2 = K A2B2 [H 2 SO 4 ] 2 turned out to depend also on amine concentrations, temperature and relative humidity. We com-pared the modelled coefficients K A2B2 with the correspond-ing coefficients calculated from the atmospheric observa-tions (K obs) from environments with varying temperatures and levels of anthropogenic influence. By taking into account the modelled behaviour of J A2B2 as a function of [H 2 SO 4 ], temperature and RH, the atmospheric particle formation rate was reproduced more closely than with the traditional semi-empirical formulae based on sulphuric acid concentration only. The formation rates of clusters with two sulphuric acid and two amine molecules with different amine composi-tions (DMA or TMA or one of both) had different responses to varying meteorological conditions and concentrations of Published by Copernicus Publications on behalf of the European Geosciences Union. 9114 P. Paasonen et al.: Sulphuric acid-amine clusters in varying atmospheric conditions vapours participating in particle formation. The observed in-verse proportionality of the coefficient K obs with RH and temperature agreed best with the modelled coefficient K A2B2 related to formation of a cluster with two H 2 SO 4 and one or two TMA molecules, assuming that these clusters can grow in collisions with abundant organic vapour molecules. In case this assumption is valid, our results suggest that the forma-tion rate of clusters with at least two of both sulphuric acid and amine molecules might be the rate-limiting step for at-mospheric particle formation. More generally, our analysis elucidates the sensitivity of the atmospheric particle forma-tion rate to meteorological variables and concentrations of vapours participating in particle formation (also other than H 2 SO 4).},
 bibtype = {article},
 author = {Paasonen, P. and Olenius, T. and Kupiainen, O. and KurtÃn, T. and Petäjä, T. and Birmili, W. and Hamed, A. and Hu, M. and Huey, L. G. and Plass-Duelmer, C. and Smith, J. N. and Wiedensohler, A. and Loukonen, V. and McGrath, M. J. and Ortega, I. K. and Laaksonen, A. and Vehkamäki, H. and Kulmala, M.},
 doi = {10.5194/acp-12-9113-2012},
 journal = {Atmospheric Chemistry and Physics},
 number = {19}
}

Sulphuric acid is a key component in atmo-spheric new particle formation. However, sulphuric acid alone does not form stable enough clusters to initiate par-ticle formation in atmospheric conditions. Strong bases, such as amines, have been suggested to stabilize sulphuric acid clusters and thus participate in particle formation. We modelled the formation rate of clusters with two sulphuric acid and two amine molecules (J A2B2) at varying atmo-spherically relevant conditions with respect to concentrations of sulphuric acid ([H 2 SO 4 ]), dimethylamine ([DMA]) and trimethylamine ([TMA]), temperature and relative humidity (RH). We also tested how the model results change if we assume that the clusters with two sulphuric acid and two amine molecules would act as seeds for heterogeneous nucle-ation of organic vapours (other than amines) with higher at-mospheric concentrations than sulphuric acid. The modelled formation rates J A2B2 were functions of sulphuric acid con-centration with close to quadratic dependence, which is in good agreement with atmospheric observations of the con-nection between the particle formation rate and sulphuric acid concentration. The coefficients K A2B2 connecting the cluster formation rate and sulphuric acid concentrations as J A2B2 = K A2B2 [H 2 SO 4 ] 2 turned out to depend also on amine concentrations, temperature and relative humidity. We com-pared the modelled coefficients K A2B2 with the correspond-ing coefficients calculated from the atmospheric observa-tions (K obs) from environments with varying temperatures and levels of anthropogenic influence. By taking into account the modelled behaviour of J A2B2 as a function of [H 2 SO 4 ], temperature and RH, the atmospheric particle formation rate was reproduced more closely than with the traditional semi-empirical formulae based on sulphuric acid concentration only. The formation rates of clusters with two sulphuric acid and two amine molecules with different amine composi-tions (DMA or TMA or one of both) had different responses to varying meteorological conditions and concentrations of Published by Copernicus Publications on behalf of the European Geosciences Union. 9114 P. Paasonen et al.: Sulphuric acid-amine clusters in varying atmospheric conditions vapours participating in particle formation. The observed in-verse proportionality of the coefficient K obs with RH and temperature agreed best with the modelled coefficient K A2B2 related to formation of a cluster with two H 2 SO 4 and one or two TMA molecules, assuming that these clusters can grow in collisions with abundant organic vapour molecules. In case this assumption is valid, our results suggest that the forma-tion rate of clusters with at least two of both sulphuric acid and amine molecules might be the rate-limiting step for at-mospheric particle formation. More generally, our analysis elucidates the sensitivity of the atmospheric particle forma-tion rate to meteorological variables and concentrations of vapours participating in particle formation (also other than H 2 SO 4).

@article{
 title = {Observations of inorganic bromine (HOBr, BrO, and Br2) speciation at Barrow, Alaska, in spring 2009},
 type = {article},
 year = {2012},
 pages = {n/a-n/a},
 volume = {117},
 websites = {http://doi.wiley.com/10.1029/2011JD016641},
 month = {7},
 day = {27},
 id = {515c535e-2e0a-35f8-a337-f693f749daf9},
 created = {2023-01-31T22:46:06.157Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:06.157Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Liao2012},
 source_type = {Journal Article},
 notes = {<b>From Duplicate 1 (<i>Observations of inorganic bromine (HOBr, BrO, and Br2) speciation at Barrow, Alaska, in spring 2009</i> - Liao, J.; Huey, L. G.; Tanner, D. J.; Flocke, F. M.; Orlando, J. J.; Neuman, J. A.; Nowak, J. B.; Weinheimer, A. J.; Hall, S. R.; Smith, J. N.; Fried, A.; Staebler, R. M.; Wang, Y.; Koo, J. H.; Cantrell, C. A.; Weibring, P.; Walega, J.; Knapp, D. J.; Shepson, P. B.; Stephens, C. R.)<br/></b><br/>Times Cited: 2<br/>Liao, J. Huey, L. G. Tanner, D. J. Flocke, F. M. Orlando, J. J. Neuman, J. A. Nowak, J. B. Weinheimer, A. J. Hall, S. R. Smith, J. N. Fried, A. Staebler, R. M. Wang, Y. Koo, J-H. Cantrell, C. A. Weibring, P. Walega, J. Knapp, D. J. Shepson, P. B. Stephens, C. R.<br/><br/><b>From Duplicate 2 (<i>Observations of inorganic bromine (HOBr, BrO, and Br2) speciation at Barrow, Alaska, in spring 2009</i> - Liao, J.; Huey, L. G.; Tanner, D. J.; Flocke, F. M.; Orlando, J. J.; Neuman, J. A.; Nowak, J. B.; Weinheimer, A. J.; Hall, S. R.; Smith, J. N.; Fried, A.; Staebler, R. M.; Wang, Y.; Koo, J. H.; Cantrell, C. A.; Weibring, P.; Walega, J.; Knapp, D. J.; Shepson, P. B.; Stephens, C. R.)<br/></b><br/><b>From Duplicate 1 (<i>Observations of inorganic bromine (HOBr, BrO, and Br2) speciation at Barrow, Alaska, in spring 2009</i> - Liao, J.; Huey, L. G.; Tanner, D. J.; Flocke, F. M.; Orlando, J. J.; Neuman, J. A.; Nowak, J. B.; Weinheimer, A. J.; Hall, S. R.; Smith, J. N.; Fried, A.; Staebler, R. M.; Wang, Y.; Koo, J. H.; Cantrell, C. A.; Weibring, P.; Walega, J.; Knapp, D. J.; Shepson, P. B.; Stephens, C. R.)<br/></b><br/>Times Cited: 2 Liao, J. Huey, L. G. Tanner, D. J. Flocke, F. M. Orlando, J. J. Neuman, J. A. Nowak, J. B. Weinheimer, A. J. Hall, S. R. Smith, J. N. Fried, A. Staebler, R. M. Wang, Y. Koo, J-H. Cantrell, C. A. Weibring, P. Walega, J. Knapp, D. J. Shepson, P. B. Stephens, C. R.<br/><br/><b>From Duplicate 2 (<i>Observations of inorganic bromine (HOBr, BrO, and Br-2) speciation at Barrow, Alaska, in spring 2009</i> - Liao, J; Huey, L G; Tanner, D J; Flocke, F M; Orlando, J J; Neuman, J A; Nowak, J B; Weinheimer, A J; Hall, S R; Smith, J N; Fried, A; Staebler, R M; Wang, Y; Koo, J H; Cantrell, C A; Weibring, P; Walega, J; Knapp, D J; Shepson, P B; Stephens, C R)<br/></b><br/>Times Cited: 2<br/>Liao, J. Huey, L. G. Tanner, D. J. Flocke, F. M. Orlando, J. J. Neuman, J. A. Nowak, J. B. Weinheimer, A. J. Hall, S. R. Smith, J. N. Fried, A. Staebler, R. M. Wang, Y. Koo, J-H. Cantrell, C. A. Weibring, P. Walega, J. Knapp, D. J. Shepson, P. B. Stephens, C. R.},
 private_publication = {false},
 abstract = {Inorganic bromine plays a critical role in ozone and mercury depletions events (ODEs and MDEs) in the Arctic marine boundary layer. Direct observations of bromine species other than bromine oxide (BrO) during ODEs are very limited. Here we report the first direct measurements of hypobromous acid (HOBr) as well as observations of BrO and molecular bromine (Br2) by chemical ionization mass spectrometry at Barrow, Alaska in spring 2009 during the Ocean-Atmospheric-Sea Ice-Snowpack (OASIS) campaign. Diurnal profiles of HOBr with maximum concentrations near local noon and no significant concentrations at night were observed. The measured average daytime HOBr mixing ratio was 10 pptv with a maximum value of 26 pptv. The observed HOBr was reasonably well correlated (R2 = 0.57) with predictions from a simple steady state photochemical model constrained to observed BrO and HO2 at wind speeds <6 m s−1. However, predicted HOBr levels were considerably higher than observations at higher wind speeds. This may be due to enhanced heterogeneous loss of HOBr on blowing snow coincident with higher wind speeds. BrO levels were also found to be higher at elevated wind speeds. Br2 was observed in significant mixing ratios (maximum = 46 pptv; average = 13 pptv) at night and was strongly anti-correlated with ozone. The diurnal speciation of observed gas phase inorganic bromine species can be predicted by a time-dependent box model that includes efficient heterogeneous recycling of HOBr, hydrogen bromide (HBr), and bromine nitrate (BrONO2) back to more reactive forms of bromine.},
 bibtype = {article},
 author = {Liao, J. and Huey, L. G. and Tanner, D. J. and Flocke, F. M. and Orlando, J. J. and Neuman, J. A. and Nowak, J. B. and Weinheimer, A. J. and Hall, S. R. and Smith, J. N. and Fried, A. and Staebler, R. M. and Wang, Y. and Koo, J. H. and Cantrell, C. A. and Weibring, P. and Walega, J. and Knapp, D. J. and Shepson, P. B. and Stephens, C. R.},
 doi = {10.1029/2011jd016641},
 journal = {Journal of Geophysical Research Atmospheres},
 number = {6}
}

Inorganic bromine plays a critical role in ozone and mercury depletions events (ODEs and MDEs) in the Arctic marine boundary layer. Direct observations of bromine species other than bromine oxide (BrO) during ODEs are very limited. Here we report the first direct measurements of hypobromous acid (HOBr) as well as observations of BrO and molecular bromine (Br2) by chemical ionization mass spectrometry at Barrow, Alaska in spring 2009 during the Ocean-Atmospheric-Sea Ice-Snowpack (OASIS) campaign. Diurnal profiles of HOBr with maximum concentrations near local noon and no significant concentrations at night were observed. The measured average daytime HOBr mixing ratio was 10 pptv with a maximum value of 26 pptv. The observed HOBr was reasonably well correlated (R2 = 0.57) with predictions from a simple steady state photochemical model constrained to observed BrO and HO2 at wind speeds <6 m s−1. However, predicted HOBr levels were considerably higher than observations at higher wind speeds. This may be due to enhanced heterogeneous loss of HOBr on blowing snow coincident with higher wind speeds. BrO levels were also found to be higher at elevated wind speeds. Br2 was observed in significant mixing ratios (maximum = 46 pptv; average = 13 pptv) at night and was strongly anti-correlated with ozone. The diurnal speciation of observed gas phase inorganic bromine species can be predicted by a time-dependent box model that includes efficient heterogeneous recycling of HOBr, hydrogen bromide (HBr), and bromine nitrate (BrONO2) back to more reactive forms of bromine.

@article{
 title = {An annual cycle of size-resolved aerosol hygroscopicity at a forested site in Colorado},
 type = {article},
 year = {2012},
 keywords = {CCN,aerosol,biogenic aerosol,hygroscopicity},
 pages = {n/a-n/a},
 volume = {117},
 websites = {papers://83c86942-09e3-4e62-b4f3-4d7a6ecab78b/Paper/p1459},
 id = {0296a9d2-2751-3c3c-8e16-a725df1002cc},
 created = {2023-01-31T22:46:08.255Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:08.255Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Levin2012},
 source_type = {Journal Article},
 notes = {<b>From Duplicate 1 (<i>An annual cycle of size-resolved aerosol hygroscopicity at a forested site in Colorado</i> - Levin, E; Prenni, a; Petters, M; Kreidenweis, S; Sullivan, R; Atwood, S; Ortega, J; Demott, P; Smith, J)<br/></b><br/>Times Cited: 24},
 private_publication = {false},
 abstract = {The ability of particles composed wholly or partially of biogenic secondary organic compounds to serve as cloud condensation nuclei (CCN) is a key characteristic that helps to define their roles in linking biogeochemical and water cycles. In this paper, we describe size-resolved (14-350 nm) CCN measurements from the Manitou Experimental Forest in Colorado, where particle compositions were expected to have a large biogenic component. These measurements were conducted for 1 year as part of the Bio-hydro-atmosphere Interactions of Energy, Aerosols, Carbon, H2O, Organics, and Nitrogen program and determined the aerosol hygroscopicity parameter, kappa, at five water supersaturations between similar to 0.14% and similar to 0.97%. The average kappa value over the entire study and all supersaturations was kappa(avg) = 0.16 +/- 0.08. Kappa values decreased slightly with increasing supersaturation, suggesting a change in aerosol composition with dry diameter. Furthermore, some seasonal variability was observed with increased CCN concentrations and activated particle number fraction, but slightly decreased hygroscopicity, during the summer. Small particle events, which may indicate new particle formation, were observed throughout the study period, especially in the summer, leading to increases in CCN concentration, followed by a gradual increase in the aerosol mode size. The condensing material appeared to be predominantly composed of organic compounds and led to a small decrease in k at the larger activation diameters during and immediately after those events.},
 bibtype = {article},
 author = {Levin, E. J. T. and Prenni, A. J. and Petters, M. D. and Kreidenweis, S. M. and Sullivan, R. C. and Atwood, S. A. and Ortega, J. and Demott, P. J. and Smith, J. N.},
 doi = {10.1029/2011jd016854},
 journal = {Journal of Geophysical Research},
 number = {D6}
}

The ability of particles composed wholly or partially of biogenic secondary organic compounds to serve as cloud condensation nuclei (CCN) is a key characteristic that helps to define their roles in linking biogeochemical and water cycles. In this paper, we describe size-resolved (14-350 nm) CCN measurements from the Manitou Experimental Forest in Colorado, where particle compositions were expected to have a large biogenic component. These measurements were conducted for 1 year as part of the Bio-hydro-atmosphere Interactions of Energy, Aerosols, Carbon, H2O, Organics, and Nitrogen program and determined the aerosol hygroscopicity parameter, kappa, at five water supersaturations between similar to 0.14% and similar to 0.97%. The average kappa value over the entire study and all supersaturations was kappa(avg) = 0.16 +/- 0.08. Kappa values decreased slightly with increasing supersaturation, suggesting a change in aerosol composition with dry diameter. Furthermore, some seasonal variability was observed with increased CCN concentrations and activated particle number fraction, but slightly decreased hygroscopicity, during the summer. Small particle events, which may indicate new particle formation, were observed throughout the study period, especially in the summer, leading to increases in CCN concentration, followed by a gradual increase in the aerosol mode size. The condensing material appeared to be predominantly composed of organic compounds and led to a small decrease in k at the larger activation diameters during and immediately after those events.

@article{
 title = {Effect of aerosol size distribution changes on AOD, CCN and cloud droplet concentration: Case studies from Erfurt and Melpitz, Germany},
 type = {article},
 year = {2012},
 pages = {n/a-n/a},
 volume = {117},
 websites = {http://doi.wiley.com/10.1029/2011JD017091},
 month = {4},
 day = {16},
 id = {fa1ba26b-ae0a-3127-94d0-22d6d41871f3},
 created = {2023-01-31T22:46:16.428Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:16.428Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Romakkaniemi2012},
 source_type = {Journal Article},
 private_publication = {false},
 abstract = {For the period of 1990 to 2000, atmospheric particulate mass concentrations have decreased in Central Europe. Simultaneously, the amount of shortwave radiation reaching the ground increased during clear sky conditions. The aerosol indirect effect has not been seen as clearly, as the radiation reaching the ground during overcast conditions has not increased as much as might be expected. Here we show that this may be caused by the condensation kinetics of water during cloud droplet formation. The decrease in the particulate mass led to a clear decrease in the number concentration of cloud condensation nuclei (CCN). However, in urban areas a relatively larger decrease in the number of particles in the upper end of the accumulation mode has led to slower condensation of water. As a result, a higher maximum supersaturation is reached during the cloud droplet formation. This compensates for the effect of decreased CCN concentrations. For example in Erfurt between 1991 and 1996, the aerosol properties changed so that aerosol optical depth decreased by 58% and CCN concentration decreased by 25 to 50%. These led to a 4 to 12% reduction in cloud droplet number concentration (CDNC) and less than a 2 Wm<sup>-2</sup> increase in shortwave radiation during overcast conditions. These results demonstrate that locally the aerosol direct effect can be much larger than the aerosol indirect effect. Furthermore, even though AOD appears to be a valid proxy for CCN, the correlation between AOD and CDNC is not straightforward and thus AOD cannot be used as a proxy for CDNC.},
 bibtype = {article},
 author = {Romakkaniemi, S. and Arola, A. and Kokkola, H. and Birmili, W. and Tuch, T. and Kerminen, V.-M. M. and Räisänen, P. and Smith, J. N. and Korhonen, H. and Laaksonen, A.},
 doi = {10.1029/2011JD017091},
 journal = {Journal of Geophysical Research Atmospheres},
 number = {7}
}

For the period of 1990 to 2000, atmospheric particulate mass concentrations have decreased in Central Europe. Simultaneously, the amount of shortwave radiation reaching the ground increased during clear sky conditions. The aerosol indirect effect has not been seen as clearly, as the radiation reaching the ground during overcast conditions has not increased as much as might be expected. Here we show that this may be caused by the condensation kinetics of water during cloud droplet formation. The decrease in the particulate mass led to a clear decrease in the number concentration of cloud condensation nuclei (CCN). However, in urban areas a relatively larger decrease in the number of particles in the upper end of the accumulation mode has led to slower condensation of water. As a result, a higher maximum supersaturation is reached during the cloud droplet formation. This compensates for the effect of decreased CCN concentrations. For example in Erfurt between 1991 and 1996, the aerosol properties changed so that aerosol optical depth decreased by 58% and CCN concentration decreased by 25 to 50%. These led to a 4 to 12% reduction in cloud droplet number concentration (CDNC) and less than a 2 Wm^-2 increase in shortwave radiation during overcast conditions. These results demonstrate that locally the aerosol direct effect can be much larger than the aerosol indirect effect. Furthermore, even though AOD appears to be a valid proxy for CCN, the correlation between AOD and CDNC is not straightforward and thus AOD cannot be used as a proxy for CDNC.

@article{
 title = {The role of relative humidity in continental new particle formation},
 type = {article},
 year = {2011},
 pages = {D03202},
 volume = {116},
 websites = {http://doi.wiley.com/10.1029/2010JD014186},
 month = {2},
 day = {1},
 id = {eb5d90e5-08e9-3a8f-b4db-795f5e017729},
 created = {2016-07-07T17:20:53.000Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-08-21T23:00:50.342Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Hamed2011},
 source_type = {Journal Article},
 private_publication = {false},
 abstract = {Relative humidity (RH) has been observed to be anticorrelated with continental new particle formation. Several reasons have been proposed for this rather surprising finding, but no firm conclusions have been drawn so far. Here we study several of the proposed reasons: Enhanced coagulational scavenging of sub-3 nm clusters at high RH, diminished solar radiation at high RH leading to diminished gas phase oxidation chemistry, and increased condensation sink (CS) of condensable gases due to hygroscopic growth of the preexisting particles. Our theoretical calculations indicate that the increase of coagulational scavenging plays a relatively small role in the inhibition of nucleation at high RH. On the other hand, field data show that the maximum observed gas phase sulphuric acid concentrations are limited to RHs below 60%. The field data also indicate that this is likely due to low OH concentrations at high RH. This finding is also supported by aerosol dynamics model simulations. The model was used to find out whether this is mainly due to decreased source (solar radiation) or increased sink (CS) terms at the elevated RH. The simulation results show that the decreased source term at high RH limits H<inf>2</inf>SO<inf>4</inf> levels in the air, and therefore high new particle formation rates (above ∼1 cm<sup>-3</sup> s<sup>-1</sup>) rarely occur above 80% RH. Copyright 2011 by the American Geophysical Union.},
 bibtype = {article},
 author = {Hamed, Amar and Korhonen, Hannele and Sihto, Sanna Liisa and Joutsensaari, Jorma and Jrvinen, Heikki and Petäjä, Tuukka and Arnold, Frank and Nieminen, Tuomo and Kulmala, Markku and Smith, James N. and Lehtinen, Kari E.J. and Laaksonen, Ari},
 doi = {10.1029/2010JD014186},
 journal = {Journal of Geophysical Research Atmospheres},
 number = {3}
}

Relative humidity (RH) has been observed to be anticorrelated with continental new particle formation. Several reasons have been proposed for this rather surprising finding, but no firm conclusions have been drawn so far. Here we study several of the proposed reasons: Enhanced coagulational scavenging of sub-3 nm clusters at high RH, diminished solar radiation at high RH leading to diminished gas phase oxidation chemistry, and increased condensation sink (CS) of condensable gases due to hygroscopic growth of the preexisting particles. Our theoretical calculations indicate that the increase of coagulational scavenging plays a relatively small role in the inhibition of nucleation at high RH. On the other hand, field data show that the maximum observed gas phase sulphuric acid concentrations are limited to RHs below 60%. The field data also indicate that this is likely due to low OH concentrations at high RH. This finding is also supported by aerosol dynamics model simulations. The model was used to find out whether this is mainly due to decreased source (solar radiation) or increased sink (CS) terms at the elevated RH. The simulation results show that the decreased source term at high RH limits H2SO4 levels in the air, and therefore high new particle formation rates (above ∼1 cm^-3 s^-1) rarely occur above 80% RH. Copyright 2011 by the American Geophysical Union.

@article{
 title = {Partitioning of semivolatile surface-active compounds between bulk, surface and gas phase},
 type = {article},
 year = {2011},
 pages = {n/a-n/a},
 volume = {38},
 websites = {http://doi.wiley.com/10.1029/2010GL046147},
 month = {2},
 id = {5d4abcd2-9433-3321-aba6-158e0848ca78},
 created = {2016-07-07T17:21:01.000Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-11-02T20:28:32.706Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Romakkaniemi2011},
 source_type = {Journal Article},
 private_publication = {false},
 abstract = {We present a model study demonstrating that surface partitioning of volatile surfactants enhances their uptake by submicron liquid droplets. In submicron-sized droplets, surface partitioning of a surface-active volatile species may significantly decrease its equilibrium partial pressure, thus increasing the total flux of the surfactant from gas phase to aqueous phase. Such uptake of volatile organic species into aqueous aerosols can be followed by aqueous-phase chemistry to form low-volatility secondary organic aerosol material, leading to increased aerosol mass. In the study, we used an air parcel model that includes simplified aqueous- and gas-phase chemistry, condensation/evaporation, and a model of aqueous-phase thermodynamics that takes into account the partitioning of surfactants between the bulk and surface phases. We modeled the uptake and aqueous-phase chemical reactions of methylglyoxal, as it is a moderate surfactant that forms less volatile secondary organic material via aqueous-phase chemical reactions with the hydroxyl radical as well as hydronium and ammonium ions. Our model simulations show an order of magnitude higher uptake of methylglyoxal in aqueous aerosols of cloud condensation nuclei sizes (less than 200 nm in radius) when surface partitioning is taken into account, compared to when surface partitioning is neglected. As a consequence, the production of SOA through the aqueous-phase chemical processing of methylglyoxal is also enhanced, but to a lesser degree, because condensation of the hydroxyl radical from gas phase limits the production. Copyright 2011 by the American Geophysical Union.},
 bibtype = {article},
 author = {Romakkaniemi, S. and Kokkola, H. and Smith, J. N. and Prisle, N. L. and Schwier, A. N. and McNeill, V. F. and Laaksonen, A.},
 doi = {10.1029/2010GL046147},
 journal = {Geophysical Research Letters},
 number = {3}
}

We present a model study demonstrating that surface partitioning of volatile surfactants enhances their uptake by submicron liquid droplets. In submicron-sized droplets, surface partitioning of a surface-active volatile species may significantly decrease its equilibrium partial pressure, thus increasing the total flux of the surfactant from gas phase to aqueous phase. Such uptake of volatile organic species into aqueous aerosols can be followed by aqueous-phase chemistry to form low-volatility secondary organic aerosol material, leading to increased aerosol mass. In the study, we used an air parcel model that includes simplified aqueous- and gas-phase chemistry, condensation/evaporation, and a model of aqueous-phase thermodynamics that takes into account the partitioning of surfactants between the bulk and surface phases. We modeled the uptake and aqueous-phase chemical reactions of methylglyoxal, as it is a moderate surfactant that forms less volatile secondary organic material via aqueous-phase chemical reactions with the hydroxyl radical as well as hydronium and ammonium ions. Our model simulations show an order of magnitude higher uptake of methylglyoxal in aqueous aerosols of cloud condensation nuclei sizes (less than 200 nm in radius) when surface partitioning is taken into account, compared to when surface partitioning is neglected. As a consequence, the production of SOA through the aqueous-phase chemical processing of methylglyoxal is also enhanced, but to a lesser degree, because condensation of the hydroxyl radical from gas phase limits the production. Copyright 2011 by the American Geophysical Union.

@article{
 title = {On-line characterization of morphology and water adsorption on fumed silica nanoparticles},
 type = {article},
 year = {2011},
 keywords = {agglomerate aerosols,differential mobility analyzer,dispersion,electrodynamic balance,environment,hygroscopic properties,particles,pressure,size,surfaces},
 pages = {1441-1447},
 volume = {45},
 id = {120d74ef-7b02-3bca-8932-3e10f8566f49},
 created = {2019-12-30T23:08:27.029Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-11-02T20:28:31.925Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Keskinen2011},
 source_type = {Journal Article},
 language = {English},
 notes = {<b>From Duplicate 1 (<i>On-Line Characterization of Morphology and Water Adsorption on Fumed Silica Nanoparticles</i> - Keskinen, H; Romakkaniemi, S; Jaatinen, A; Miettinen, P; Saukko, E; Jorma, J; Makela, J M; Virtanen, A; Smith, J N; Laaksonen, A)<br/></b><br/>816MS<br/>Times Cited:0<br/>Cited References Count:37},
 private_publication = {false},
 abstract = {The first wetting layer on solid nanoparticles has direct implications on the roles these particles play in industrial processes and technological applications as well as in the atmosphere. We present a technique for online measurements of the adsorption of the first few water layers onto insoluble aerosol nanoparticles. Atomized fumed silica nanoparticles were dispersed from aqueous suspension and their hygroscopic growth factors (HGF) and number of the adsorbed water layers at subsaturated conditions were measured using a nanometer hygroscopic tandem differential mobility analyzer (HTDMA). Particle morphology was characterized by electron microscopy and particle density was determined by mobility analysis. The HGFs of the size-selected particles at mobility diameters from 10 to 50 nm at 90% relative humidity (RH) varied from 1.05 to 1.24, corresponding to 2-6 layers of adsorbed water. The morphology of the generated fumed silica nanoparticles varied from spheres at 8-10 nm to agglomerates at larger diameters with effective density from 1.7 to 0.8 g/cm 3 and fractal dimension of 2.6. The smallest spheres and agglomerates had the highest HGFs. The smallest particles with diameters of 8 and 10 nm adsorbed two to three water layers in subsaturated conditions, which agreed well with the Frenkel, Halsey, and Hill (FHH) isotherm fitting. In comparison to the small spheres or large agglomerates, the compact agglomerate structure containing a few primary particles increased the number of adsorbed water layers by a factor of ∼1.5. This was probably caused by the capillary effect on the small cavities between the primary particles in the agglomerate. Copyright © 2011 American Association for Aerosol Research.},
 bibtype = {article},
 author = {Keskinen, Helmi and Romakkaniemi, Sami and Jaatinen, Antti and Miettinen, Pasi and Saukko, Erkka and Jorma, Joutsensaari and Makela, Jyrki M. and Virtanen, Annele and Smith, James N. and Laaksonen, Ari},
 doi = {10.1080/02786826.2011.597459},
 journal = {Aerosol Science and Technology},
 number = {12}
}

The first wetting layer on solid nanoparticles has direct implications on the roles these particles play in industrial processes and technological applications as well as in the atmosphere. We present a technique for online measurements of the adsorption of the first few water layers onto insoluble aerosol nanoparticles. Atomized fumed silica nanoparticles were dispersed from aqueous suspension and their hygroscopic growth factors (HGF) and number of the adsorbed water layers at subsaturated conditions were measured using a nanometer hygroscopic tandem differential mobility analyzer (HTDMA). Particle morphology was characterized by electron microscopy and particle density was determined by mobility analysis. The HGFs of the size-selected particles at mobility diameters from 10 to 50 nm at 90% relative humidity (RH) varied from 1.05 to 1.24, corresponding to 2-6 layers of adsorbed water. The morphology of the generated fumed silica nanoparticles varied from spheres at 8-10 nm to agglomerates at larger diameters with effective density from 1.7 to 0.8 g/cm 3 and fractal dimension of 2.6. The smallest spheres and agglomerates had the highest HGFs. The smallest particles with diameters of 8 and 10 nm adsorbed two to three water layers in subsaturated conditions, which agreed well with the Frenkel, Halsey, and Hill (FHH) isotherm fitting. In comparison to the small spheres or large agglomerates, the compact agglomerate structure containing a few primary particles increased the number of adsorbed water layers by a factor of ∼1.5. This was probably caused by the capillary effect on the small cavities between the primary particles in the agglomerate. Copyright © 2011 American Association for Aerosol Research.

@article{
 title = {Bounce behavior of freshly nucleated biogenic secondary organic aerosol particles},
 type = {article},
 year = {2011},
 keywords = {atmospheric particles,density,events,evolution,impact,oxidation,phase-transitions},
 pages = {8759-8766},
 volume = {11},
 websites = {http://www.atmos-chem-phys.net/11/8759/2011/},
 month = {8},
 day = {29},
 id = {2d8d3f47-4b78-3778-b998-31daf37c6ce2},
 created = {2023-01-31T22:46:06.780Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:06.780Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Virtanen2011},
 source_type = {Journal Article},
 language = {English},
 notes = {<b>From Duplicate 1 (<i>Bounce behavior of freshly nucleated biogenic secondary organic aerosol particles</i> - Virtanen, A.; Kannosto, J.; Kuuluvainen, H.; Arffman, A.; Joutsensaari, J.; Saukko, E.; Hao, L.; Yli-Pirilä, P.; Tiitta, P.; Holopainen, J. K.; Keskinen, J.; Worsnop, D. R.; Smith, J. N.; Laaksonen, A.)<br/></b><br/><b>From Duplicate 1 (<i>Bounce behavior of freshly nucleated biogenic secondary organic aerosol particles</i> - Virtanen, A.; Kannosto, J.; Kuuluvainen, H.; Arffman, A.; Joutsensaari, J.; Saukko, E.; Hao, L.; Yli-Pirilä, P.; Tiitta, P.; Holopainen, J. K.; Keskinen, J.; Worsnop, D. R.; Smith, J. N.; Laaksonen, A.)<br/></b><br/>813YL<br/>Times Cited:6<br/>Cited References Count:30<br/><br/><b>From Duplicate 2 (<i>Bounce behavior of freshly nucleated biogenic secondary organic aerosol particles</i> - Virtanen, A.; Kannosto, J.; Kuuluvainen, H.; Arffman, A.; Joutsensaari, J.; Saukko, E.; Hao, L.; Yli-Pirilä, P.; Tiitta, P.; Holopainen, J. K.; Keskinen, J.; Worsnop, D. R.; Smith, J. N.; Laaksonen, A.; Yli-Pirila, P; Tiitta, P.; Holopainen, J. K.; Keskinen, J.; Worsnop, D. R.; Smith, J. N.; Laaksonen, A.)<br/></b><br/><b>From Duplicate 1 (<i>Bounce behavior of freshly nucleated biogenic secondary organic aerosol particles</i> - Virtanen, A; Kannosto, J; Kuuluvainen, H; Arffman, A; Joutsensaari, J; Saukko, E; Hao, L; Yli-Pirila, P; Tiitta, P; Holopainen, J K; Keskinen, J; Worsnop, D R; Smith, J N; Laaksonen, A)<br/>And Duplicate 3 (<i>Bounce behavior of freshly nucleated biogenic secondary organic aerosol particles</i> - Virtanen, A.; Kannosto, J.; Kuuluvainen, H.; Arffman, A.; Joutsensaari, J.; Saukko, E.; Hao, L.; Yli-Pirilä, P.; Tiitta, P.; Holopainen, J. K.; Keskinen, J.; Worsnop, D. R.; Smith, J. N.; Laaksonen, A.)<br/></b><br/>813YL<br/>Times Cited:6<br/>Cited References Count:30<br/><br/><b>From Duplicate 2 (<i>Bounce behavior of freshly nucleated biogenic secondary organic aerosol particles</i> - Virtanen, A.; Kannosto, J.; Kuuluvainen, H.; Arffman, A.; Joutsensaari, J.; Saukko, E.; Hao, L.; Yli-Pirilä, P.; Tiitta, P.; Holopainen, J. K.; Keskinen, J.; Worsnop, D. R.; Smith, J. N.; Laaksonen, A.)<br/></b><br/>813YL<br/>Times Cited:6<br/>Cited References Count:30},
 private_publication = {false},
 abstract = {The assessment of the climatic impacts and adverse health effects of atmospheric aerosol particles requires detailed information on particle properties. However, very limited information is available on the morphology and phase state of secondary organic aerosol (SOA) particles. The physical state of particles greatly affects particulate-phase chemical reactions, and thus the growth rates of newly formed atmospheric aerosol. Thus verifying the physical phase state of SOA particles gives new and important insight into their formation, subsequent growth, and consequently potential atmospheric impacts. According to our recent study, biogenic SOA particles produced in laboratory chambers from the oxidation of real plant emissions as well as in ambient boreal forest atmospheres can exist in a solid phase in size range > 30 nm. In this paper, we extend previously published results to diameters in the range of 17-30 nm. The physical phase of the particles is studied by investigating particle bounce properties utilizing electrical low pressure impactor (ELPI). We also investigate the effect of estimates of particle density on the interpretation of our bounce observations. According to the results presented in this paper, particle bounce clearly decreases with decreasing particle size in sub 30 nm size range. The comparison measurements by ammonium sulphate and investigation of the particle impaction velocities strongly suggest that the decreasing bounce is caused by the differences in composition and phase of large (diameters greater than 30 nm) and smaller (diameters between 17 and 30 nm) particles.},
 bibtype = {article},
 author = {Virtanen, A. and Kannosto, J. and Kuuluvainen, H. and Arffman, A. and Joutsensaari, J. and Saukko, E. and Hao, L. and Yli-Pirilä, P. and Tiitta, P. and Holopainen, J. K. and Keskinen, J. and Worsnop, D. R. and Smith, J. N. and Laaksonen, A.},
 doi = {10.5194/acp-11-8759-2011},
 journal = {Atmospheric Chemistry and Physics},
 number = {16}
}

The assessment of the climatic impacts and adverse health effects of atmospheric aerosol particles requires detailed information on particle properties. However, very limited information is available on the morphology and phase state of secondary organic aerosol (SOA) particles. The physical state of particles greatly affects particulate-phase chemical reactions, and thus the growth rates of newly formed atmospheric aerosol. Thus verifying the physical phase state of SOA particles gives new and important insight into their formation, subsequent growth, and consequently potential atmospheric impacts. According to our recent study, biogenic SOA particles produced in laboratory chambers from the oxidation of real plant emissions as well as in ambient boreal forest atmospheres can exist in a solid phase in size range > 30 nm. In this paper, we extend previously published results to diameters in the range of 17-30 nm. The physical phase of the particles is studied by investigating particle bounce properties utilizing electrical low pressure impactor (ELPI). We also investigate the effect of estimates of particle density on the interpretation of our bounce observations. According to the results presented in this paper, particle bounce clearly decreases with decreasing particle size in sub 30 nm size range. The comparison measurements by ammonium sulphate and investigation of the particle impaction velocities strongly suggest that the decreasing bounce is caused by the differences in composition and phase of large (diameters greater than 30 nm) and smaller (diameters between 17 and 30 nm) particles.

@article{
 title = {Aerosol hygroscopicity and CCN activation kinetics in a boreal forest environment during the 2007 EUCAARI campaign},
 type = {article},
 year = {2011},
 keywords = {cloud condensation nuclei,distributions,droplet growth-kinetics,mass-spectrometer,nucleation,particle growth,secondary organic aerosol,single-component,size-resolved measurements,sulfuric-acid},
 pages = {12369-12386},
 volume = {11},
 websites = {http://www.atmos-chem-phys.net/11/12369/2011/},
 month = {12},
 day = {9},
 id = {cf8783aa-79fa-3d6a-815e-78f74ba5d5b5},
 created = {2023-01-31T22:46:07.877Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:07.877Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Cerully2011},
 source_type = {Journal Article},
 language = {English},
 notes = {<b>From Duplicate 1 (<i>Aerosol hygroscopicity and CCN activation kinetics in a boreal forest environment during the 2007 EUCAARI campaign</i> - Cerully, K. M.; Raatikainen, T.; Lance, S.; Tkacik, D.; Tiitta, P.; Petäjä, T.; Ehn, M.; Kulmala, M.; Worsnop, D. R.; Laaksonen, A.; Smith, J. N.; Nenes, A.)<br/></b><br/>863AD<br/>Times Cited:10<br/>Cited References Count:85},
 private_publication = {false},
 abstract = {Measurements of size-resolved cloud condensation nuclei (CCN) concentrations, subsaturated hygroscopic growth, size distribution, and chemical composition were collected from March through May, 2007, in the remote Boreal forests of Hyytiälä, Finland, as part of the European Integrated project on Aerosol Cloud Climate and Air Quality Interactions (EUCAARI) campaign. Hygroscopicity parameter, κ, distributions were derived independently from Continuous Flow-Streamwise Thermal Gradient CCN Chamber (CFSTGC) and Hygroscopicity Tandem Differential Mobility Analyzer (HTDMA) measurements. CFSTGC-derived κ values for 40, 60, and 80 nm particles range mostly between 0.10 and 0.40 with an average characteristic of highly oxidized organics of 0.20 ± 0.10, indicating that organics play a dominant role for this environment. HTDMA-derived κ were generally 30% lower. Diurnal trends of κ show a minimum at sunrise and a maximum in the late afternoon; this trend covaries with inorganic mass fraction and the m/z 44 organic mass fraction given by a quadrupole aerosol mass spectrometer, further illustrating the importance of organics in aerosol hygroscopicity. The chemical dispersion inferred from the observed κ distributions indicates that while 60 and 80 nm dispersion increases around midday, 40 nm dispersion remains constant. Additionally, 80 nm particles show a markedly higher level of chemical dispersion than both 40 and 60 nm particles. An analysis of droplet activation kinetics for the sizes considered indicates that most of the CCN activate as rapidly as (NH 4) 2SO 4 calibration aerosol. © 2011 Author(s).},
 bibtype = {article},
 author = {Cerully, K. M. and Raatikainen, T. and Lance, S. and Tkacik, D. and Tiitta, P. and Petaja, T and Ehn, M. and Kulmala, M. and Worsnop, D. R. and Laaksonen, A. and Smith, J. N. and Nenes, A. and Petäjä, T. and Ehn, M. and Kulmala, M. and Worsnop, D. R. and Laaksonen, A. and Smith, J. N. and Nenes, A.},
 doi = {10.5194/acp-11-12369-2011},
 journal = {Atmospheric Chemistry and Physics},
 number = {23}
}

Measurements of size-resolved cloud condensation nuclei (CCN) concentrations, subsaturated hygroscopic growth, size distribution, and chemical composition were collected from March through May, 2007, in the remote Boreal forests of Hyytiälä, Finland, as part of the European Integrated project on Aerosol Cloud Climate and Air Quality Interactions (EUCAARI) campaign. Hygroscopicity parameter, κ, distributions were derived independently from Continuous Flow-Streamwise Thermal Gradient CCN Chamber (CFSTGC) and Hygroscopicity Tandem Differential Mobility Analyzer (HTDMA) measurements. CFSTGC-derived κ values for 40, 60, and 80 nm particles range mostly between 0.10 and 0.40 with an average characteristic of highly oxidized organics of 0.20 ± 0.10, indicating that organics play a dominant role for this environment. HTDMA-derived κ were generally 30% lower. Diurnal trends of κ show a minimum at sunrise and a maximum in the late afternoon; this trend covaries with inorganic mass fraction and the m/z 44 organic mass fraction given by a quadrupole aerosol mass spectrometer, further illustrating the importance of organics in aerosol hygroscopicity. The chemical dispersion inferred from the observed κ distributions indicates that while 60 and 80 nm dispersion increases around midday, 40 nm dispersion remains constant. Additionally, 80 nm particles show a markedly higher level of chemical dispersion than both 40 and 60 nm particles. An analysis of droplet activation kinetics for the sizes considered indicates that most of the CCN activate as rapidly as (NH 4) 2SO 4 calibration aerosol. © 2011 Author(s).

@article{
 title = {First size-dependent growth rate measurements of 1 to 5 nm freshly formed atmospheric nuclei},
 type = {article},
 year = {2011},
 pages = {25427-25471},
 volume = {12},
 websites = {http://10.0.20.74/acp-12-3573-2012,http://www.atmos-chem-phys-discuss.net/11/25427/2011/},
 id = {aedc0c5e-a094-3015-bcf2-115e8ac9a3e7},
 created = {2023-01-31T22:46:08.017Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:08.017Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Kuang2012},
 source_type = {article},
 private_publication = {false},
 abstract = {Abstract. This study presents the first measurements of size-dependent particle diameter growth rates for freshly nucleated particles down to 1 nm geometric diameter. Data analysis methods were developed, de-coupling the size and time-dependence of particle growth rates by fitting the aerosol general dynamic equation to size distributions obtained at an instant in time. Size distributions of freshly nucleated particles were measured during two intensive measurement campaigns in different environments (Atlanta, GA and Boulder, CO) using a recently developed electrical mobility spectrometer with a diethylene glycol-based ultrafine condensation particle counter as the detector. Size and time-dependent growth rates were obtained directly from measured size distributions and were found to increase approximately linearly with size from ~1 to 3 nm geometric diameter, ranging, for example, from 5.6 ± 2.0 to 27 ± 5.3 nm h−1 in Boulder (13:00) and from 5.5 ± 0.82 to 7.6 ± 0.56 nm h−1 in Atlanta (13:00). The resulting growth rate enhancement Γ, defined as the ratio of the observed growth rate to the growth rate due to the condensation of sulfuric acid only, was found to increase approximately linearly with size from ~1 to 3 nm geometric diameter, having lower limit values that approached ~1 at 1.2 nm geometric diameter in Atlanta and ~3 at 0.8 nm geometric diameter in Boulder, and having upper limit values that reached 8.3 at 4.1 nm geometric diameter in Atlanta and 25 at 2.7 nm geometric diameter in Boulder. Survival probability calculations comparing constant and size-dependent growth indicate that neglecting the strong growth rate size dependence from 1 to 3 nm observed in this study could lead to a significant overestimation of CCN survival probability.},
 bibtype = {article},
 author = {Kuang, C. and Chen, M. and Zhao, J. and Smith, J. and McMurry, P. H. and Wang, J.},
 doi = {10.5194/acp-12-3573-2012},
 journal = {Atmospheric Chemistry and Physics},
 number = {7},
 keywords = {Kuang2012}
}

Abstract. This study presents the first measurements of size-dependent particle diameter growth rates for freshly nucleated particles down to 1 nm geometric diameter. Data analysis methods were developed, de-coupling the size and time-dependence of particle growth rates by fitting the aerosol general dynamic equation to size distributions obtained at an instant in time. Size distributions of freshly nucleated particles were measured during two intensive measurement campaigns in different environments (Atlanta, GA and Boulder, CO) using a recently developed electrical mobility spectrometer with a diethylene glycol-based ultrafine condensation particle counter as the detector. Size and time-dependent growth rates were obtained directly from measured size distributions and were found to increase approximately linearly with size from ~1 to 3 nm geometric diameter, ranging, for example, from 5.6 ± 2.0 to 27 ± 5.3 nm h−1 in Boulder (13:00) and from 5.5 ± 0.82 to 7.6 ± 0.56 nm h−1 in Atlanta (13:00). The resulting growth rate enhancement Γ, defined as the ratio of the observed growth rate to the growth rate due to the condensation of sulfuric acid only, was found to increase approximately linearly with size from ~1 to 3 nm geometric diameter, having lower limit values that approached ~1 at 1.2 nm geometric diameter in Atlanta and ~3 at 0.8 nm geometric diameter in Boulder, and having upper limit values that reached 8.3 at 4.1 nm geometric diameter in Atlanta and 25 at 2.7 nm geometric diameter in Boulder. Survival probability calculations comparing constant and size-dependent growth indicate that neglecting the strong growth rate size dependence from 1 to 3 nm observed in this study could lead to a significant overestimation of CCN survival probability.

@article{
 title = {Meteorological and trace gas factors affecting the number concentration of atmospheric Aitken (DP Combining double low line 50 nm) particles in the continental boundary layer: Parameterization using a multivariate mixed effects model},
 type = {article},
 year = {2011},
 keywords = {central-europe,chemical-transport model,growth,microphysics,nucleation events,oxidation-products,rates,size-resolved aerosol,sulfate aerosol,sulfuric-acid},
 pages = {1-13},
 volume = {4},
 websites = {http://www.geosci-model-dev.net/4/1/2011/},
 month = {1},
 day = {11},
 id = {f5f637ce-55b0-34ff-aeda-36fb18c8eb4d},
 created = {2023-01-31T22:46:08.733Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:08.733Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Mikkonen2011},
 source_type = {Journal Article},
 language = {English},
 notes = {<b>From Duplicate 1 (<i>Meteorological and trace gas factors affecting the number concentration of atmospheric Aitken (DP Combining double low line 50 nm) particles in the continental boundary layer: Parameterization using a multivariate mixed effects model</i> - Mikkonen, S.; Korhonen, H.; Romakkaniemi, S.; Smith, J. N.; Joutsensaari, J.; Lehtinen, K. E.J.; Hamed, A.; Breider, T. J.; Birmili, W.; Spindler, G.; Plass-Duelmer, C.; Facchini, M. C.; Laaksonen, A.)<br/></b><br/>742AO<br/>Times Cited:5<br/>Cited References Count:43<br/><br/><b>From Duplicate 2 (<i>Meteorological and trace gas factors affecting the number concentration of atmospheric Aitken (DPCombining double low line 50 nm) particles in the continental boundary layer: Parameterization using a multivariate mixed effects model</i> - Mikkonen, S.; Korhonen, H.; Romakkaniemi, S.; Smith, J. N.; Joutsensaari, J.; Lehtinen, K. E.J. J; Hamed, A.; Breider, T. J.; Birmili, W.; Spindler, G.; Plass-Duelmer, C.; Facchini, M. C.; Laaksonen, A.)<br/></b><br/><b>From Duplicate 1 (<i>Meteorological and trace gas factors affecting the number concentration of atmospheric Aitken (DPCombining double low line 50 nm) particles in the continental boundary layer: Parameterization using a multivariate mixed effects model</i> - Mikkonen, S.; Korhonen, H.; Romakkaniemi, S.; Smith, J. N.; Joutsensaari, J.; Lehtinen, K. E.J.; Hamed, A.; Breider, T. J.; Birmili, W.; Spindler, G.; Plass-Duelmer, C.; Facchini, M. C.; Laaksonen, A.)<br/></b><br/>742AO<br/>Times Cited:5<br/>Cited References Count:43},
 private_publication = {false},
 abstract = {Measurements of aerosol size distribution and different gas andmeteorological parameters, made in three polluted sites in Central andSouthern Europe: Po Valley, Italy, Melpitz and Hohenpeissenberg in Germany,were analysed for this study to examine which of the meteorological and tracegas variables affect the number concentration of Aitken (D PCombining double low line 50 nm)particles. The aim of our study was to predict the number concentration of50 nm particles by a combination of in-situ meteorological and gas phaseparameters. The statistical model needs to describe, amongst others, thefactors affecting the growth of newly formed aerosol particles (below 10 nm)to 50 nm size, but also sources of direct particle emissions in that sizerange. As the analysis method we used multivariate nonlinear mixed effectsmodel. Hourly averages of gas and meteorological parameters measured at thestations were used as predictor variables; the best predictive model wasattained with a combination of relative humidity, new particle formationevent probability, temperature, condensation sink and concentrations ofSO2, NO2 and ozone. The seasonal variation was also taken into accountin the mixed model structure. Model simulations with the Global Model ofAerosol Processes (GLOMAP) indicate that the parameterization can be used asa part of a larger atmospheric model to predict the concentration ofclimatically active particles. As an additional benefit, the introduced modelframework is, in theory, applicable for any kind of measured aerosolparameter. © 2011 Author(s).},
 bibtype = {article},
 author = {Mikkonen, S. and Korhonen, H. and Romakkaniemi, S. and Smith, J. N. and Joutsensaari, J. and Lehtinen, K. E.J. J and Hamed, A. and Breider, T. J. and Birmili, W. and Spindler, G. and Plass-Duelmer, C. and Facchini, M. C. and Laaksonen, A.},
 doi = {10.5194/gmd-4-1-2011},
 journal = {Geoscientific Model Development},
 number = {1}
}

Measurements of aerosol size distribution and different gas andmeteorological parameters, made in three polluted sites in Central andSouthern Europe: Po Valley, Italy, Melpitz and Hohenpeissenberg in Germany,were analysed for this study to examine which of the meteorological and tracegas variables affect the number concentration of Aitken (D PCombining double low line 50 nm)particles. The aim of our study was to predict the number concentration of50 nm particles by a combination of in-situ meteorological and gas phaseparameters. The statistical model needs to describe, amongst others, thefactors affecting the growth of newly formed aerosol particles (below 10 nm)to 50 nm size, but also sources of direct particle emissions in that sizerange. As the analysis method we used multivariate nonlinear mixed effectsmodel. Hourly averages of gas and meteorological parameters measured at thestations were used as predictor variables; the best predictive model wasattained with a combination of relative humidity, new particle formationevent probability, temperature, condensation sink and concentrations ofSO2, NO2 and ozone. The seasonal variation was also taken into accountin the mixed model structure. Model simulations with the Global Model ofAerosol Processes (GLOMAP) indicate that the parameterization can be used asa part of a larger atmospheric model to predict the concentration ofclimatically active particles. As an additional benefit, the introduced modelframework is, in theory, applicable for any kind of measured aerosolparameter. © 2011 Author(s).

@article{
 title = {Mass yields of secondary organic aerosols from the oxidation of α-pinene and real plant emissions},
 type = {article},
 year = {2011},
 keywords = {absorption-model,beta-pinene,biogenic hydrocarbons,forest,growth,norway spruce,particle formation,soa,spectrometer,terpene ozonolysis},
 pages = {1367-1378},
 volume = {11},
 websites = {http://www.atmos-chem-phys.net/11/1367/2011/},
 month = {2},
 day = {16},
 id = {f8bcbaff-d5f3-3a55-b3f5-0ca664137a76},
 created = {2023-01-31T22:46:09.571Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:09.571Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Hao2011},
 source_type = {Journal Article},
 language = {English},
 notes = {<b>From Duplicate 1 (<i>Mass yields of secondary organic aerosols from the oxidation of α-pinene and real plant emissions</i> - Hao, L. Q.; Romakkaniemi, S.; Yli-Pirilä, P.; Joutsensaari, J.; Kortelainen, A.; Kroll, J. H.; Miettinen, P.; Vaattovaara, P.; Tiitta, P.; Jaatinen, A.; Kajos, M. K.; Holopainen, J. K.; Heijari, J.; Rinne, J.; Kulmala, M.; Worsnop, D. R.; Smith, J. N.; Laaksonen, A.)<br/></b><br/><b>From Duplicate 1 (<i>Mass yields of secondary organic aerosols from the oxidation of α-pinene and real plant emissions</i> - Hao, L. Q.; Romakkaniemi, S.; Yli-Pirilä, P.; Joutsensaari, J.; Kortelainen, A.; Kroll, J. H.; Miettinen, P.; Vaattovaara, P.; Tiitta, P.; Jaatinen, A.; Kajos, M. K.; Holopainen, J. K.; Heijari, J.; Rinne, J.; Kulmala, M.; Worsnop, D. R.; Smith, J. N.; Laaksonen, A.)<br/></b><br/>727JW<br/>Times Cited:11<br/>Cited References Count:68<br/><br/><b>From Duplicate 2 (<i>Mass yields of secondary organic aerosols from the oxidation of α-pinene and real plant emissions</i> - Hao, L. Q.; Romakkaniemi, S.; Yli-Pirila, P; Joutsensaari, J.; Kortelainen, A.; Kroll, J. H.; Miettinen, P.; Vaattovaara, P.; Tiitta, P.; Jaatinen, A.; Kajos, M. K.; Holopainen, J. K.; Heijari, J.; Rinne, J.; Kulmala, M.; Worsnop, D. R.; Smith, J. N.; Laaksonen, A.; Yli-Pirilä, P.; Joutsensaari, J.; Kortelainen, A.; Kroll, J. H.; Miettinen, P.; Vaattovaara, P.; Tiitta, P.; Jaatinen, A.; Kajos, M. K.; Holopainen, J. K.; Heijari, J.; Rinne, J.; Kulmala, M.; Worsnop, D. R.; Smith, J. N.; Laaksonen, A.)<br/></b><br/><b>From Duplicate 1 (<i>Mass yields of secondary organic aerosols from the oxidation of α-pinene and real plant emissions</i> - Hao, L. Q.; Romakkaniemi, S.; Yli-Pirilä, P.; Joutsensaari, J.; Kortelainen, A.; Kroll, J. H.; Miettinen, P.; Vaattovaara, P.; Tiitta, P.; Jaatinen, A.; Kajos, M. K.; Holopainen, J. K.; Heijari, J.; Rinne, J.; Kulmala, M.; Worsnop, D. R.; Smith, J. N.; Laaksonen, A.)<br/></b><br/>727JW<br/>Times Cited:11<br/>Cited References Count:68<br/><br/><b>From Duplicate 2 (<i>Mass yields of secondary organic aerosols from the oxidation of α-pinene and real plant emissions</i> - Hao, L. Q.; Romakkaniemi, S.; Yli-Pirila, P; Joutsensaari, J.; Kortelainen, A.; Kroll, J. H.; Miettinen, P.; Vaattovaara, P.; Tiitta, P.; Jaatinen, A.; Kajos, M. K.; Holopainen, J. K.; Heijari, J.; Rinne, J.; Kulmala, M.; Worsnop, D. R.; Smith, J. N.; Laaksonen, A.; Yli-Pirilä, P.; Joutsensaari, J.; Kortelainen, A.; Kroll, J. H.; Miettinen, P.; Vaattovaara, P.; Tiitta, P.; Jaatinen, A.; Kajos, M. K.; Holopainen, J. K.; Heijari, J.; Rinne, J.; Kulmala, M.; Worsnop, D. R.; Smith, J. N.; Laaksonen, A.)<br/></b><br/><b>From Duplicate 1 (<i>Mass yields of secondary organic aerosols from the oxidation of α-pinene and real plant emissions</i> - Hao, L. Q.; Romakkaniemi, S.; Yli-Pirilä, P.; Joutsensaari, J.; Kortelainen, A.; Kroll, J. H.; Miettinen, P.; Vaattovaara, P.; Tiitta, P.; Jaatinen, A.; Kajos, M. K.; Holopainen, J. K.; Heijari, J.; Rinne, J.; Kulmala, M.; Worsnop, D. R.; Smith, J. N.; Laaksonen, A.)<br/></b><br/>727JW<br/>Times Cited:11<br/>Cited References Count:68},
 private_publication = {false},
 abstract = {Biogenic volatile organic compounds (VOCs) are a significant source of global secondary organic aerosol (SOA); however, quantifying their aerosol forming potential remains a challenge. This study presents smog chamber laboratory work, focusing on SOA formation via oxidation of the emissions of two dominant tree species from boreal forest area, Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies), by hydroxyl radical (OH) and ozone (O 3). Oxidation of α-pinene was also studied as a reference system. Tetramethylethylene (TME) and 2-butanol were added to control OH and O3 levels, thereby allowing SOA formation events to be categorized as resulting from either OH-dominated or O3-initiated chemistry. SOA mass yields from α-pinene are consistent with previous studies while the yields from the real plant emissions are generally lower than that from α-pinene, varying from 1.9% at an aerosol mass loading of 0.69 μg m-3 to 17.7% at 26.0 μg m-3. Mass yields from oxidation of real plant emissions are subject to the interactive effects of the molecular structures of plant emissions and their reaction chemistry with OH and O3, which lead to variations in condensable product volatility. SOA formation can be reproduced with a two-product gas-phase partitioning absorption model in spite of differences in the source of oxidant species and product volatility in the real plant emission experiments. Condensable products from OH-dominated chemistry showed a higher volatility than those from O3-initiated systems during aerosol growth stage. Particulate phase products became less volatile via aging process which continued after input gas-phase oxidants had been completely consumed. © 2011 Author(s).},
 bibtype = {article},
 author = {Hao, L. Q. and Romakkaniemi, S. and Yli-Pirila, P and Joutsensaari, J. and Kortelainen, A. and Kroll, J. H. and Miettinen, P. and Vaattovaara, P. and Tiitta, P. and Jaatinen, A. and Kajos, M. K. and Holopainen, J. K. and Heijari, J. and Rinne, J. and Kulmala, M. and Worsnop, D. R. and Smith, J. N. and Laaksonen, A. and Yli-Pirilä, P. and Joutsensaari, J. and Kortelainen, A. and Kroll, J. H. and Miettinen, P. and Vaattovaara, P. and Tiitta, P. and Jaatinen, A. and Kajos, M. K. and Holopainen, J. K. and Heijari, J. and Rinne, J. and Kulmala, M. and Worsnop, D. R. and Smith, J. N. and Laaksonen, A.},
 doi = {10.5194/acp-11-1367-2011},
 journal = {Atmospheric Chemistry and Physics},
 number = {4}
}

Biogenic volatile organic compounds (VOCs) are a significant source of global secondary organic aerosol (SOA); however, quantifying their aerosol forming potential remains a challenge. This study presents smog chamber laboratory work, focusing on SOA formation via oxidation of the emissions of two dominant tree species from boreal forest area, Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies), by hydroxyl radical (OH) and ozone (O 3). Oxidation of α-pinene was also studied as a reference system. Tetramethylethylene (TME) and 2-butanol were added to control OH and O3 levels, thereby allowing SOA formation events to be categorized as resulting from either OH-dominated or O3-initiated chemistry. SOA mass yields from α-pinene are consistent with previous studies while the yields from the real plant emissions are generally lower than that from α-pinene, varying from 1.9% at an aerosol mass loading of 0.69 μg m-3 to 17.7% at 26.0 μg m-3. Mass yields from oxidation of real plant emissions are subject to the interactive effects of the molecular structures of plant emissions and their reaction chemistry with OH and O3, which lead to variations in condensable product volatility. SOA formation can be reproduced with a two-product gas-phase partitioning absorption model in spite of differences in the source of oxidant species and product volatility in the real plant emission experiments. Condensable products from OH-dominated chemistry showed a higher volatility than those from O3-initiated systems during aerosol growth stage. Particulate phase products became less volatile via aging process which continued after input gas-phase oxidants had been completely consumed. © 2011 Author(s).

@article{
 title = {Ion mobility distributions during the initial stages of new particle formation by the ozonolysis of α-pinene},
 type = {article},
 year = {2010},
 pages = {8917-8923},
 volume = {44},
 websites = {http://pubs.acs.org/doi/abs/10.1021/es101572u},
 month = {12},
 id = {3590a144-9585-39b4-a52a-84aed746a75b},
 created = {2023-01-31T22:46:10.558Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:10.558Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Viitanen2010},
 source_type = {JOUR},
 private_publication = {false},
 abstract = {An ion mobility spectrometer (IMS) was used to study gas phase compounds during nucleation and growth of secondary organic aerosols (SOA). In this study SOA particles were generated by oxidizing α-pinene with O3 and OH in a 6 m3 reaction chamber. Positive ion peaks with reduced mobilities of 1.59 cm2(Vs)-1 and 1.05 cm 2(Vs)-1 were observed 7 min after α-pinene and ozone were added to the chamber. The detected compounds can be associated with low volatility oxidation products of α-pinene, which have been suggested to participate in new particle formation. This is the first time that IMS has been applied to laboratory studies of SOA formation. IMS was found suitable for continuous online monitoring of the SOA formation process, allowing for highly sensitive detection of gas phase species that are thought to initiate new particle formation. © 2010 American Chemical Society.},
 bibtype = {article},
 author = {Viitanen, Anna Kaisa and Saukko, Erkka and Virtanen, Annele and Yli-Pirila, P and Smith, James N. and Joutsensaari, Jorma and Makela, J M and Yli-Pirilä, Pasi and Smith, James N. and Joutsensaari, Jorma and Mäkelä, Jyrki M.},
 doi = {10.1021/es101572u},
 journal = {Environmental Science and Technology},
 number = {23}
}

An ion mobility spectrometer (IMS) was used to study gas phase compounds during nucleation and growth of secondary organic aerosols (SOA). In this study SOA particles were generated by oxidizing α-pinene with O3 and OH in a 6 m3 reaction chamber. Positive ion peaks with reduced mobilities of 1.59 cm2(Vs)-1 and 1.05 cm 2(Vs)-1 were observed 7 min after α-pinene and ozone were added to the chamber. The detected compounds can be associated with low volatility oxidation products of α-pinene, which have been suggested to participate in new particle formation. This is the first time that IMS has been applied to laboratory studies of SOA formation. IMS was found suitable for continuous online monitoring of the SOA formation process, allowing for highly sensitive detection of gas phase species that are thought to initiate new particle formation. © 2010 American Chemical Society.

@article{
 title = {A thermal desorption chemical ionization ion trap mass spectrometer for the chemical characterization of ultrafine aerosol particles},
 type = {article},
 year = {2009},
 pages = {264-272},
 volume = {43},
 id = {1d2e837a-6117-36f1-bcdc-cb0187235670},
 created = {2016-07-07T17:20:32.000Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-08-21T23:00:48.687Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Held2009},
 source_type = {Journal Article},
 language = {English},
 notes = {Cited References Count:21|TAYLOR & FRANCIS INC|325 CHESTNUT ST, SUITE 800, PHILADELPHIA, PA 19106 USA|ISI Document Delivery No.:394HO},
 private_publication = {false},
 abstract = {The development of a thermal desorption chemical ionization ion trap mass spectrometer for the chemical characterization of ultrafine aerosol particles is reported and first experimental results are presented. Atmospheric particles are size-classified and collected using a unipolar charger, a radial differential mobility analyzer and an electrostatic precipitator, and analyzed after thermal desorption and chemical ionization using an ion trap mass spectrometer. Integration of an ion trap mass spectrometer allows for fast scans of the entire mass spectrum every 0.5 s and bears the potential to identify unknown particulate compounds by tandem mass spectrometry. Particle collection efficiencies range from 90–100% for 25 nm particles to about 50% for 40 nm particles. In the current configuration, the absolute sensitivity of the instrument with regard to ammonium is in the range of 10–100 pg NH+4. In ambient samples collected in the Colorado Front Range, NH+4 was the major signal peak in the positive ion spectrum, and additional minor signals and peak patterns of organic compounds including methylamine were found. © 2009 Taylor & Francis Group, LLC.},
 bibtype = {article},
 author = {Held, Andreas and Rathbone, G. Jeffrey and Smith, James N. and Held, Andreas},
 doi = {10.1080/02786820802603792},
 journal = {Aerosol Science and Technology},
 number = {3}
}

The development of a thermal desorption chemical ionization ion trap mass spectrometer for the chemical characterization of ultrafine aerosol particles is reported and first experimental results are presented. Atmospheric particles are size-classified and collected using a unipolar charger, a radial differential mobility analyzer and an electrostatic precipitator, and analyzed after thermal desorption and chemical ionization using an ion trap mass spectrometer. Integration of an ion trap mass spectrometer allows for fast scans of the entire mass spectrum every 0.5 s and bears the potential to identify unknown particulate compounds by tandem mass spectrometry. Particle collection efficiencies range from 90–100% for 25 nm particles to about 50% for 40 nm particles. In the current configuration, the absolute sensitivity of the instrument with regard to ammonium is in the range of 10–100 pg NH+4. In ambient samples collected in the Colorado Front Range, NH+4 was the major signal peak in the positive ion spectrum, and additional minor signals and peak patterns of organic compounds including methylamine were found. © 2009 Taylor & Francis Group, LLC.

@article{
 title = {Sampling nanoparticles for chemical analysis by low resolution electrical mobility classification},
 type = {article},
 year = {2009},
 keywords = {p572.pdf},
 pages = {4653-4658},
 volume = {43},
 websites = {http://pubs.acs.org/doi/abs/10.1021/es8029335},
 month = {7},
 id = {8d5dd4ec-b67d-3bf3-bd1c-0062b37d8cb7},
 created = {2020-08-21T23:09:04.024Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-08-21T23:13:22.748Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Mcmurry2009},
 source_type = {Journal Article},
 language = {English},
 notes = {<b>From Duplicate 1 (<i>Sampling Nanoparticles for Chemical Analysis by Low Resolution Electrical Mobility Classification</i> - McMurry, P H; Ghimire, A; Ahn, H K; Sakurai, H; Moore, K; Stolzenburg, M; Smith, J N)<br/></b><br/>463ME<br/>Times Cited:12<br/>Cited References Count:41<br/><br/><b>From Duplicate 2 (<i>Sampling nanoparticles for chemical analysis by low resolution electrical mobility classification</i> - Mcmurry, Peter H.; Ghimire, Ajaya; Ahn, Hyo Kueh; Sakurai, Hiromu; Moore, Katharine; Stolzenburg, Mark; Smith, James N.)<br/></b><br/><b>From Duplicate 2 (<i>Sampling Nanoparticles for Chemical Analysis by Low Resolution Electrical Mobility Classification</i> - McMurry, P H; Ghimire, A; Ahn, H K; Sakurai, H; Moore, K; Stolzenburg, M; Smith, J N)<br/></b><br/>463ME<br/>Times Cited:12<br/>Cited References Count:41<br/><br/><b>From Duplicate 4 (<i>Sampling Nanoparticles for Chemical Analysis by Low Resolution Electrical Mobility Classification</i> - McMurry, Peter H.; Ghimire, Ajaya; Ahn, Hyo-Kueh; Sakurai, Hiromu; Moore, Katharine; Stolzenburg, Mark; Smith, James N.)<br/></b><br/>Cited References Count:41|AMER CHEMICAL SOC|1155 16TH ST, NW, WASHINGTON, DC 20036 USA|ISI Document Delivery No.:463ME},
 folder_uuids = {166824d9-9061-4c8b-bfd7-92a782f92781},
 private_publication = {false},
 abstract = {The use of electrostatic classification to collect samples of aerosol nanoparticles for chemical analysis is discussed. Our technique exposes the aerosol to negative ions in a unipolar charger with subsequent mobility classification at low resolution and high sampling rate. The negative unipolar charger produces high charged fractions. The low-resolution mobility classifier enables the delivery of high mass concentrations in a well-defined mobility range. The mobility-classified particles are collected by electrostatic precipitation. We summarize experimental and computational work on the performance of the unipolar charger, and we describe the performance of the overall system when used to sample atmospheric particles. For a size distribution measured in Atlanta during a new particle formation event, calculated mass sampling rates of ∼8 nm particles were about 150 pg/h. © 2009 American Chemical Society.},
 bibtype = {article},
 author = {Mcmurry, Peter H. and Ghimire, Ajaya and Ahn, Hyo Kueh and Sakurai, Hiromu and Moore, Katharine and Stolzenburg, Mark and Smith, James N.},
 doi = {10.1021/es8029335},
 journal = {Environmental Science and Technology},
 number = {13}
}

The use of electrostatic classification to collect samples of aerosol nanoparticles for chemical analysis is discussed. Our technique exposes the aerosol to negative ions in a unipolar charger with subsequent mobility classification at low resolution and high sampling rate. The negative unipolar charger produces high charged fractions. The low-resolution mobility classifier enables the delivery of high mass concentrations in a well-defined mobility range. The mobility-classified particles are collected by electrostatic precipitation. We summarize experimental and computational work on the performance of the unipolar charger, and we describe the performance of the overall system when used to sample atmospheric particles. For a size distribution measured in Atlanta during a new particle formation event, calculated mass sampling rates of ∼8 nm particles were about 150 pg/h. © 2009 American Chemical Society.

@article{
 title = {New particle formation from the oxidation of direct emissions of pine seedlings},
 type = {article},
 year = {2009},
 keywords = {alpha-pinene,atmospheric degradation,biogenic hydrocarbons,gas-phase reactions,growth-rates,mass-spectrometer,methyl-substituted ethenes,scots pine,secondary organic aerosol,size distribution},
 pages = {8121-8137},
 volume = {9},
 id = {81dbd4b7-61c6-392f-9207-65d707a64a92},
 created = {2023-01-31T22:46:07.749Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:07.749Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Hao2009},
 source_type = {Journal Article},
 language = {English},
 notes = {<b>From Duplicate 2 (<i>New particle formation from the oxidation of direct emissions of pine seedlings</i> - Hao, L. Q.; Yli-Pirilä, P.; Tiitta, P.; Romakkaniemi, S.; Vaattovaara, P.; Kajos, M. K.; Rinne, J.; Heijari, J.; Kortelainen, A.; Miettinen, P.; Kroll, J. H.; Holopainen, J. K.; Smith, J. N.; Joutsensaari, J.; Kulmala, M.; Worsnop, D. R.; Laaksonen, A.; Yli-Pirila, P; Tiitta, P.; Romakkaniemi, S.; Vaattovaara, P.; Kajos, M. K.; Rinne, J.; Heijari, J.; Kortelainen, A.; Miettinen, P.; Kroll, J. H.; Holopainen, J. K.; Smith, J. N.; Joutsensaari, J.; Kulmala, M.; Worsnop, D. R.; Laaksonen, A.)<br/></b><br/><b>From Duplicate 2 (<i>New particle formation from the oxidation of direct emissions of pine seedlings</i> - Hao, L. Q.; Yli-Pirilä, P.; Tiitta, P.; Romakkaniemi, S.; Vaattovaara, P.; Kajos, M. K.; Rinne, J.; Heijari, J.; Kortelainen, A.; Miettinen, P.; Kroll, J. H.; Holopainen, J. K.; Smith, J. N.; Joutsensaari, J.; Kulmala, M.; Worsnop, D. R.; Laaksonen, A.)<br/></b><br/>512IL<br/>Times Cited:16<br/>Cited References Count:75},
 private_publication = {false},
 abstract = {Measurements of particle formation following the gas phase oxidation of volatile organic compounds (VOCs) emitted by Scots pine (Pinus sylvestrisL.) seedlings are reported. Particle formation and condensational growth both from ozone (O3) and hydroxyl radical (OH) initiated oxidation of pine emissions (about 20-120 ppb) were investigated in a smog chamber. During experiments, tetramethylethylene (TME) and 2-butanol were added to control the concentrations of O3 and OH. Particle formation and condensational growth rates were interpreted with a chemical kinetic model. Scots pine emissions mainly included ±-pinene, β2-pinene, Δ3-carene, limonene, myrcene and 2-phellandrene, composing more than 95% of total emissions. Modeled OH concentrations in the O3-and OH-induced experiments were on the order of ∼106 molecules cm&minus;3. Our results demonstrate that OH-initiated oxidation of VOCs plays an important role in the nucleation process during the initial new particle formation stage. The highest average particle formation rate of 360 cm&minus;3 s&minus;1 was observed for the OH-dominated nucleation events and the lowest formation rate of less than 0.5 cm&minus;3 s&minus;1 was observed for the case with only O3 present as an oxidant. In contrast to the particle formation process, ozonolysis of monoterpenes appears to be much more efficient to the aerosol growth process following nucleation. Higher contributions of more oxygenated products to the SOA mass loadings from OH-dominated oxidation systems were found as compared to the ozonolysis systems. Comparison of mass and volume distributions from the aerosol mass spectrometer and differential mobility analyzer yields estimated SOA effective densities of 1.34&plusmn;0.06 g cm&minus;3 for the OH+O3 oxidation systems and 1.38&plusmn;0.03 g cm&minus;3 for the O3 dominated chemistry.},
 bibtype = {article},
 author = {Hao, L. Q. and Yli-Pirilä, P. and Tiitta, P. and Romakkaniemi, S. and Vaattovaara, P. and Kajos, M. K. and Rinne, J. and Heijari, J. and Kortelainen, A. and Miettinen, P. and Kroll, J. H. and Holopainen, J. K. and Smith, J. N. and Joutsensaari, J. and Kulmala, M. and Worsnop, D. R. and Laaksonen, A. and Yli-Pirila, P and Tiitta, P. and Romakkaniemi, S. and Vaattovaara, P. and Kajos, M. K. and Rinne, J. and Heijari, J. and Kortelainen, A. and Miettinen, P. and Kroll, J. H. and Holopainen, J. K. and Smith, J. N. and Joutsensaari, J. and Kulmala, M. and Worsnop, D. R. and Laaksonen, A.},
 doi = {10.5194/acp-9-8121-2009},
 journal = {Atmospheric Chemistry and Physics},
 number = {20}
}

Measurements of particle formation following the gas phase oxidation of volatile organic compounds (VOCs) emitted by Scots pine (Pinus sylvestrisL.) seedlings are reported. Particle formation and condensational growth both from ozone (O3) and hydroxyl radical (OH) initiated oxidation of pine emissions (about 20-120 ppb) were investigated in a smog chamber. During experiments, tetramethylethylene (TME) and 2-butanol were added to control the concentrations of O3 and OH. Particle formation and condensational growth rates were interpreted with a chemical kinetic model. Scots pine emissions mainly included ±-pinene, β2-pinene, Δ3-carene, limonene, myrcene and 2-phellandrene, composing more than 95% of total emissions. Modeled OH concentrations in the O3-and OH-induced experiments were on the order of ∼106 molecules cm−3. Our results demonstrate that OH-initiated oxidation of VOCs plays an important role in the nucleation process during the initial new particle formation stage. The highest average particle formation rate of 360 cm−3 s−1 was observed for the OH-dominated nucleation events and the lowest formation rate of less than 0.5 cm−3 s−1 was observed for the case with only O3 present as an oxidant. In contrast to the particle formation process, ozonolysis of monoterpenes appears to be much more efficient to the aerosol growth process following nucleation. Higher contributions of more oxygenated products to the SOA mass loadings from OH-dominated oxidation systems were found as compared to the ozonolysis systems. Comparison of mass and volume distributions from the aerosol mass spectrometer and differential mobility analyzer yields estimated SOA effective densities of 1.34±0.06 g cm−3 for the OH+O3 oxidation systems and 1.38±0.03 g cm−3 for the O3 dominated chemistry.

@article{
 title = {The potential contribution of organic salts to new particle growth},
 type = {article},
 year = {2009},
 pages = {2949-2957},
 volume = {9},
 websites = {https://www.atmos-chem-phys.net/9/2949/2009/},
 id = {73d20e9a-e447-3b8e-b83a-8e9dbd191814},
 created = {2023-01-31T22:46:15.759Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:15.759Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Barsanti2009},
 source_type = {Journal Article},
 language = {English},
 notes = {<b>From Duplicate 2 (<i>The potential contribution of organic salts to new particle growth</i> - Barsanti, K. C.; McMurry, P. H.; Smith, J. N.)<br/></b><br/><b>From Duplicate 1 (<i>The potential contribution of organic salts to new particle growth</i> - Barsanti, K C; McMurry, Peter H; Smith, J N)<br/></b><br/>Cited References Count:66|COPERNICUS PUBLICATIONS|MAX-PLANCK-STR 13, KATHLENBURG-LINDAU, 37191, GERMANY|ISI Document Delivery No.:447KJ},
 private_publication = {false},
 abstract = {Field and lab measurements suggest that low-molecular weight (MW) organic acids and bases exist in accumulation and nucleation mode particles, despite their relatively high pure-liquid vapor pressures. The mechanism(s) by which such compounds contribute to the mass growth of existing aerosol particles and newly formed particles has not been thoroughly explored. One mechanism by which low-MW compounds may contribute to new particle growth is through the formation of organic salts. In this paper we use thermodynamic modeling to explore the potential for organic salt formation by atmospherically relevant organic acids and bases for two system types: one in which the relative contribution of ammonia vs. amines in forming organic salts was evaluated, the other in which the decrease in volatility of organic acids and bases due to organic salt formation was assessed. The modeling approach employed relied heavily on group contribution and other estimation methods for necessary physical and chemical parameters. The results of this work suggest that amines may be an important contributor to organic salt formation, and that experimental data are greatly needed to improve our understanding of organic salt formation in atmospherically relevant systems and to accurately predict the potential contribution of such salts to new particle growth. © 2011 Author(s).},
 bibtype = {article},
 author = {Barsanti, K. C. and McMurry, P. H. and Smith, J. N.},
 doi = {10.5194/acp-9-2949-2009},
 journal = {Atmospheric Chemistry and Physics},
 number = {9},
 keywords = {p490.pdf,p537.pdf}
}

Field and lab measurements suggest that low-molecular weight (MW) organic acids and bases exist in accumulation and nucleation mode particles, despite their relatively high pure-liquid vapor pressures. The mechanism(s) by which such compounds contribute to the mass growth of existing aerosol particles and newly formed particles has not been thoroughly explored. One mechanism by which low-MW compounds may contribute to new particle growth is through the formation of organic salts. In this paper we use thermodynamic modeling to explore the potential for organic salt formation by atmospherically relevant organic acids and bases for two system types: one in which the relative contribution of ammonia vs. amines in forming organic salts was evaluated, the other in which the decrease in volatility of organic acids and bases due to organic salt formation was assessed. The modeling approach employed relied heavily on group contribution and other estimation methods for necessary physical and chemical parameters. The results of this work suggest that amines may be an important contributor to organic salt formation, and that experimental data are greatly needed to improve our understanding of organic salt formation in atmospherically relevant systems and to accurately predict the potential contribution of such salts to new particle growth. © 2011 Author(s).

@article{
 title = {Relaxed eddy accumulation simulations of aerosol number fluxes and potential proxy scalars},
 type = {article},
 year = {2008},
 keywords = {Aerosol number flux,Eddy covariance,Relaxed eddy accumulation,Scalar similarity},
 pages = {451-468},
 volume = {129},
 websites = {http://link.springer.com/10.1007/s10546-008-9327-5},
 month = {12},
 day = {29},
 id = {bfe0f72c-275e-32c8-bad0-4e908ee418ca},
 created = {2016-07-07T17:21:10.000Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-11-02T20:28:32.546Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Held2008},
 source_type = {Journal Article},
 language = {English},
 notes = {Cited References Count:38|SPRINGER|VAN GODEWIJCKSTRAAT 30, 3311 GZ DORDRECHT, NETHERLANDS|ISI Document Delivery No.:368IO},
 private_publication = {false},
 abstract = {Direct eddy-covariance measurements of aerosol number fluxes obtained during the 2007 CHATS field experiment in Dixon, California, USA are compared with relaxed eddy accumulation simulations using temperature and water vapour concentration as proxy scalars. After a brief discussion of the limited time response of the aerosol measurement, the applicability of temperature and water vapour concentration as proxy scalars for aerosol number concentration is investigated by evaluating scalar and spectral correlation coefficients as simple measures of scalar similarity. In addition, the proportionality factor b, which compensates for the use of a constant sampling flow in relaxed eddy accumulation, is derived from the time series of aerosol number, temperature and water vapour, and its variability is analyzed. The reduction of the b factor due to application of a deadband, i.e. the rejection of data when the vertical wind speed is close to zero, is evaluated for all three studied scalars, and compared with published functional relationships. In this study, using temperature or water vapour as proxy scalars for aerosol number shows no advantage over the use of a constant b factor. Thus, it is suggested to apply a deadband HREA = w′/σw = 0.6 to 0.8 (where w′ is the vertical velocity fluctuation and σw is its standard deviation), to use a theoretical b factor based on a parameterization that includes a stability dependence, and to calculate the deadband effect according to a derived relation for aerosol relaxed eddy accumulation. © Springer Science+Business Media B.V. 2008.},
 bibtype = {article},
 author = {Held, Andreas and Patton, Edward and Rizzo, Luciana and Smith, Jim and Turnipseed, Andrew and Guenther, Alex},
 doi = {10.1007/s10546-008-9327-5},
 journal = {Boundary-Layer Meteorology},
 number = {3}
}

Direct eddy-covariance measurements of aerosol number fluxes obtained during the 2007 CHATS field experiment in Dixon, California, USA are compared with relaxed eddy accumulation simulations using temperature and water vapour concentration as proxy scalars. After a brief discussion of the limited time response of the aerosol measurement, the applicability of temperature and water vapour concentration as proxy scalars for aerosol number concentration is investigated by evaluating scalar and spectral correlation coefficients as simple measures of scalar similarity. In addition, the proportionality factor b, which compensates for the use of a constant sampling flow in relaxed eddy accumulation, is derived from the time series of aerosol number, temperature and water vapour, and its variability is analyzed. The reduction of the b factor due to application of a deadband, i.e. the rejection of data when the vertical wind speed is close to zero, is evaluated for all three studied scalars, and compared with published functional relationships. In this study, using temperature or water vapour as proxy scalars for aerosol number shows no advantage over the use of a constant b factor. Thus, it is suggested to apply a deadband HREA = w′/σw = 0.6 to 0.8 (where w′ is the vertical velocity fluctuation and σw is its standard deviation), to use a theoretical b factor based on a parameterization that includes a stability dependence, and to calculate the deadband effect according to a derived relation for aerosol relaxed eddy accumulation. © Springer Science+Business Media B.V. 2008.

@article{
 title = {New particle formation in the front range of the Colorado Rocky Mountains},
 type = {article},
 year = {2008},
 pages = {1577-1590},
 volume = {8},
 websites = {http://www.atmos-chem-phys.net/8/1577/2008/},
 month = {3},
 day = {17},
 id = {c529880b-b7f9-313b-85fd-cead924c93d3},
 created = {2016-07-07T17:21:12.000Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-11-02T20:28:33.114Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Boy2008},
 source_type = {Journal Article},
 language = {English},
 notes = {Cited References Count:41|COPERNICUS PUBLICATIONS|MAX-PLANCK-STR 13, KATHLENBURG-LINDAU, 37191, GERMANY|ISI Document Delivery No.:280HN},
 private_publication = {false},
 abstract = {New particle formation is of interest because of its influence on the properties of aerosol population, and due to the possible contribution of newly formed particles to cloud condensation nuclei. Currently no conclusive evidence exists as to the mechanism or mechanisms of nucleation and subsequent particle growth. However, nucleation rates exhibit a clear dependence on ambient sulphuric acid concentrations and particle growth is often attributed to the condensation of organic vapours. A detailed study of new particle formation in the Front Range of the Colorado Rocky Mountains is presented here. Gas and particle measurement data for 32 days was analyzed to identify event days, possible event days, and non-event days. A detailed analysis of nucleation and growth is provided for four days on which new particle formation was clearly observed. Evidence for the role of sesquiterpenes in new particle formation is presented.},
 bibtype = {article},
 author = {Boy, M. and Karl, T. and Turnipseed, A. and Mauldin, R. L. and Kosciuch, E. and Greenberg, J. and Rathbone, J. and Smith, J. and Held, A. and Barsanti, K. and Wehner, B. and Bauer, S. and Wiedensohler, A. and Bonn, B. and Kulmala, M. and Guenther, A.},
 doi = {10.5194/acp-8-1577-2008},
 journal = {Atmospheric Chemistry and Physics},
 number = {6}
}

New particle formation is of interest because of its influence on the properties of aerosol population, and due to the possible contribution of newly formed particles to cloud condensation nuclei. Currently no conclusive evidence exists as to the mechanism or mechanisms of nucleation and subsequent particle growth. However, nucleation rates exhibit a clear dependence on ambient sulphuric acid concentrations and particle growth is often attributed to the condensation of organic vapours. A detailed study of new particle formation in the Front Range of the Colorado Rocky Mountains is presented here. Gas and particle measurement data for 32 days was analyzed to identify event days, possible event days, and non-event days. A detailed analysis of nucleation and growth is provided for four days on which new particle formation was clearly observed. Evidence for the role of sesquiterpenes in new particle formation is presented.

@article{
 title = {An ultrafine, water-based condensation particle counter and its evaluation under field conditions},
 type = {article},
 year = {2008},
 keywords = {CONDENSATION BUTANOL AEROSOLS PARTICLES LAMINAR fl},
 pages = {862-871},
 volume = {42},
 websites = {http://www.tandfonline.com/doi/abs/10.1080/02786820802339579},
 month = {8},
 publisher = {Taylor & Francis},
 day = {28},
 id = {cf7d455d-e9af-3df7-8296-a8a726fbb611},
 created = {2019-12-30T23:08:26.236Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-08-21T23:00:47.288Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Iida2008},
 source_type = {Journal Article},
 language = {English},
 notes = {<b>From Duplicate 2 (<i>An ultrafine, water-based condensation particle counter and its evaluation under field conditions</i> - Iida, Kenjiro; Stolzenburg, Mark R.; McMurry, Peter H.; Smith, James N.; Quant, Frederick R.; Oberreit, Derek R.; Keady, Patricia B.; Eiguren-Fernandez, Arantza; Lewis, Gregory S.; Kreisberg, Nathan M.; Hering, Susanne V.)<br/></b><br/>Cited References Count:25|TAYLOR &amp; FRANCIS INC|325 CHESTNUT ST, SUITE 800, PHILADELPHIA, PA 19106 USA|ISI Document Delivery No.:348WE},
 private_publication = {false},
 abstract = {An ultrafine, water-based condensation particle counter (U-WCPC, TSI Model 3786) has been compared to a butanol-based ultrafine counter (U-BCPC, TSI Model 3025) for measurement of atmospheric and freeway-tunnel aerosols. The U-WCPC utilizes a warm, wet-walled growth tube to activate and grow particles through water condensation in a laminar-flow. It has an aerosol sampling rate of 0.3 L/min, and a nominal detection limit near 3 nm. Several field comparisons were made to the butanol-based instrument with the same nominal detection limit. For measurements of size-selected aerosols with diameters of 5 nm and larger the two instruments generally agreed, with a mean response within 5%. At 3 nm particle size differences were observed, and these differences varied with the data set. Measurements of ambient aerosol in Boulder, Colorado showed higher counting efficiency at 3 nm with the U-BCPC, while in a California freeway tunnel the opposite trend was observed, with higher counting efficiencies at 3 nm observed by the U-WCPC. For direct measurement of atmospheric aerosols, the two types of instruments yielded equivalent concentrations, independent of particle number concentration. Copyright © American Association for Aerosol Research.},
 bibtype = {article},
 author = {Iida, Kenjiro and Stolzenburg, Mark R. and McMurry, Peter H. and Smith, James N. and Quant, Frederick R. and Oberreit, Derek R. and Keady, Patricia B. and Eiguren-Fernandez, Arantza and Lewis, Gregory S. and Kreisberg, Nathan M. and Hering, Susanne V.},
 doi = {10.1080/02786820802339579},
 journal = {Aerosol Science and Technology},
 number = {10}
}

An ultrafine, water-based condensation particle counter (U-WCPC, TSI Model 3786) has been compared to a butanol-based ultrafine counter (U-BCPC, TSI Model 3025) for measurement of atmospheric and freeway-tunnel aerosols. The U-WCPC utilizes a warm, wet-walled growth tube to activate and grow particles through water condensation in a laminar-flow. It has an aerosol sampling rate of 0.3 L/min, and a nominal detection limit near 3 nm. Several field comparisons were made to the butanol-based instrument with the same nominal detection limit. For measurements of size-selected aerosols with diameters of 5 nm and larger the two instruments generally agreed, with a mean response within 5%. At 3 nm particle size differences were observed, and these differences varied with the data set. Measurements of ambient aerosol in Boulder, Colorado showed higher counting efficiency at 3 nm with the U-BCPC, while in a California freeway tunnel the opposite trend was observed, with higher counting efficiencies at 3 nm observed by the U-WCPC. For direct measurement of atmospheric aerosols, the two types of instruments yielded equivalent concentrations, independent of particle number concentration. Copyright © American Association for Aerosol Research.

@article{
 title = {Carboxylic acid characterization in nanoparticles by thermal desorption chemical ionization mass spectrometry},
 type = {article},
 year = {2008},
 keywords = {Aerosol,Carboxylic acids,Chemical ionization,Nanoparticle,Thermal desorption chemical ionization mass spectr},
 pages = {8-13},
 volume = {274},
 websites = {http://www.sciencedirect.com/science/article/pii/S1387380608001371},
 id = {99e21639-05e4-3f3b-bf8a-b92d5ec30c0c},
 created = {2023-01-31T22:46:05.378Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:05.378Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Smith2008},
 source_type = {Journal Article},
 language = {English},
 notes = {<b>From Duplicate 1 (<i>Carboxylic acid characterization in nanoparticles by thermal desorption chemical ionization mass spectrometry</i> - Smith, James N.; Rathbone, G. Jeffery)<br/></b><br/>Cited References Count:37|ELSEVIER SCIENCE BV|PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS|ISI Document Delivery No.:324QS<br/><br/><b>From Duplicate 2 (<i>Carboxylic acid characterization in nanoparticles by thermal desorption chemical ionization mass spectrometry</i> - Smith, James N.; Rathbone, G. Jeffery)<br/></b><br/><b>From Duplicate 1 (<i>Carboxylic acid characterization in nanoparticles by thermal desorption chemical ionization mass spectrometry</i> - Smith, James N.; Rathbone, G. Jeffery)<br/></b><br/><b>From Duplicate 1 (<i>Carboxylic acid characterization in nanoparticles by thermal desorption chemical ionization mass spectrometry</i> - Smith, J N; Rathbone, G J)<br/></b><br/>324QS<br/>Times Cited:13<br/>Cited References Count:37<br/><br/><b>From Duplicate 2 (<i>Carboxylic acid characterization in nanoparticles by thermal desorption chemical ionization mass spectrometry</i> - Smith, James N.; Rathbone, G. Jeffery)<br/></b><br/>Cited References Count:37|ELSEVIER SCIENCE BV|PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS|ISI Document Delivery No.:324QS<br/><br/><b>From Duplicate 2 (<i>Carboxylic acid characterization in nanoparticles by thermal desorption chemical ionization mass spectrometry</i> - Smith, J N; Rathbone, G J)<br/></b><br/>324QS<br/>Times Cited:13<br/>Cited References Count:37},
 private_publication = {false},
 abstract = {Recent improvements in the operation of the thermal desorption chemical ionization mass spectrometer allow for the characterization of organic species in 8-40 nm diameter particles. Here we describe the application of this technique to monocarboxylic and dicarboxylic acids, focusing on the response of the instrument to picogram amounts of pure and multicomponent mixtures. Monocarboxylic acids underwent minimal decomposition during analysis, and were identified by the deprotonated parent ion with a sensitivity of 3-8 Hz of integrated ion signal per picogram of sample. Measurements of a binary mixture of monocarboxylic acids showed that desorption and subsequent ionization of these compounds occur independently and have mass-normalized responses identical to pure samples. Dicarboxylic acids appear as the deprotonated parent ion as well as an important decomposition product corresponding to the loss of formic acid from the deprotonated parent. Sensitivities towards these compounds were up to 100 times higher than for the monocarboxylic acids. Experiments using 10-30 nm diameter butanedioic acid particles showed a linear response to collected particulate mass with sufficient sensitivity to support the application of this technique to the characterization of carboxylic acids in ambient atmospheric nanoparticles. © 2008 Elsevier B.V. All rights reserved.},
 bibtype = {article},
 author = {Smith, James N. and Rathbone, G. Jeffery},
 doi = {10.1016/j.ijms.2008.04.008},
 journal = {International Journal of Mass Spectrometry},
 number = {1-3}
}

Recent improvements in the operation of the thermal desorption chemical ionization mass spectrometer allow for the characterization of organic species in 8-40 nm diameter particles. Here we describe the application of this technique to monocarboxylic and dicarboxylic acids, focusing on the response of the instrument to picogram amounts of pure and multicomponent mixtures. Monocarboxylic acids underwent minimal decomposition during analysis, and were identified by the deprotonated parent ion with a sensitivity of 3-8 Hz of integrated ion signal per picogram of sample. Measurements of a binary mixture of monocarboxylic acids showed that desorption and subsequent ionization of these compounds occur independently and have mass-normalized responses identical to pure samples. Dicarboxylic acids appear as the deprotonated parent ion as well as an important decomposition product corresponding to the loss of formic acid from the deprotonated parent. Sensitivities towards these compounds were up to 100 times higher than for the monocarboxylic acids. Experiments using 10-30 nm diameter butanedioic acid particles showed a linear response to collected particulate mass with sufficient sensitivity to support the application of this technique to the characterization of carboxylic acids in ambient atmospheric nanoparticles. © 2008 Elsevier B.V. All rights reserved.

@article{
 title = {Chemical composition of atmospheric nanoparticles formed from nucleation in Tecamac, Mexico: Evidence for an important role for organic species in nanoparticle growth},
 type = {article},
 year = {2008},
 keywords = {aerosol,events,mass-spectrometry,nuclei,particle formation,rates,scales,secondary,size distributions},
 pages = {L04808},
 volume = {35},
 websites = {http://doi.wiley.com/10.1029/2007GL032523},
 month = {2},
 day = {22},
 id = {2af0f305-929f-32ac-a196-77bc8dd3fc52},
 created = {2023-01-31T22:46:06.376Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:06.376Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Smith2008a},
 source_type = {Journal Article},
 language = {English},
 notes = {<b>From Duplicate 1 (<i>Chemical composition of atmospheric nanoparticles formed from nucleation in Tecamac, Mexico: Evidence for an important role for organic species in nanoparticle growth</i> - Smith, Jim N.; Dunn, M. J.; VanReken, T. M.; Iida, K.; Stolzenburg, M. R.; McMurry, P. H.; Huey, L. G.)<br/></b><br/><b>From Duplicate 1 (<i>Chemical composition of atmospheric nanoparticles formed from nucleation in Tecamac, Mexico: Evidence for an important role for organic species in nanoparticle growth</i> - Smith, J. N.; Dunn, M. J.; VanReken, T. M.; Iida, K.; Stolzenburg, M. R.; McMurry, P. H.; Huey, L. G.)<br/></b><br/>267TD<br/>Times Cited:87<br/>Cited References Count:26<br/><br/><b>From Duplicate 2 (<i>Chemical composition of atmospheric nanoparticles formed from nucleation in Tecamac, Mexico: Evidence for an important role for organic species in nanoparticle growth</i> - Smith, Jim N.; Dunn, M. J.; VanReken, T. M.; Iida, K.; Stolzenburg, M. R.; McMurry, P. H.; Huey, L. G.)<br/></b><br/>Cited References Count:26|AMER GEOPHYSICAL UNION|2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA|ISI Document Delivery No.:267TD<br/><br/><b>From Duplicate 2 (<i>Chemical composition of atmospheric nanoparticles formed from nucleation in Tecamac, Mexico: Evidence for an important role for organic species in nanoparticle growth</i> - Smith, J. N.; Dunn, M. J.; VanReken, T. M.; Iida, K.; Stolzenburg, M. R.; McMurry, P. H.; Huey, L. G.)<br/></b><br/>267TD<br/>Times Cited:87<br/>Cited References Count:26},
 private_publication = {false},
 abstract = {We report Thermal Desorption Chemical Ionization Mass Spectrometer (TDCIMS) measurements of the composition of ambient 10-33 nm diameter particles formed from nucleation on 16 March 2006 in Tecamac, Mexico during the Megacity Initiative: Local and Global Research Observations (MILAGRO) field study. On this day, nucleated particles contained far more organics than sulfates: average ion molar ratios with measurement uncertainties for nitrate, organics and sulfur species were 6±2%, 84±5%, and 10±1%, respectively. The measured organic species include nitrogen-containing organic compounds, organic acids, and hydroxy organic acids. Independent calculations show that sulfuric acid condensation could have accounted for only 10±2% of the growth that was observed on this day, which is consistent with the TDCIMS measurements of composition. It follows that organic compounds play a dominant role the high growth rates that were observed. Copyright 2008 by the American Geophysical Union.},
 bibtype = {article},
 author = {Smith, Jim N. and Dunn, M. J. and VanReken, T. M. and Iida, K. and Stolzenburg, M. R. and McMurry, P. H. and Huey, L. G.},
 doi = {10.1029/2007GL032523},
 journal = {Geophysical Research Letters},
 number = {4}
}

We report Thermal Desorption Chemical Ionization Mass Spectrometer (TDCIMS) measurements of the composition of ambient 10-33 nm diameter particles formed from nucleation on 16 March 2006 in Tecamac, Mexico during the Megacity Initiative: Local and Global Research Observations (MILAGRO) field study. On this day, nucleated particles contained far more organics than sulfates: average ion molar ratios with measurement uncertainties for nitrate, organics and sulfur species were 6±2%, 84±5%, and 10±1%, respectively. The measured organic species include nitrogen-containing organic compounds, organic acids, and hydroxy organic acids. Independent calculations show that sulfuric acid condensation could have accounted for only 10±2% of the growth that was observed on this day, which is consistent with the TDCIMS measurements of composition. It follows that organic compounds play a dominant role the high growth rates that were observed. Copyright 2008 by the American Geophysical Union.

@article{
 title = {Estimating nanoparticle growth rates from size-dependent charged fractions: Analysis of new particle formation events in Mexico City},
 type = {article},
 year = {2008},
 keywords = {p495.pdf},
 pages = {n/a-n/a},
 volume = {113},
 websites = {http://doi.wiley.com/10.1029/2007JD009260},
 month = {3},
 day = {16},
 id = {1cc42910-0b5b-3c14-ab11-b7c2835652f1},
 created = {2023-01-31T22:46:07.426Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:07.426Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Iida2008a},
 source_type = {Journal Article},
 language = {English},
 notes = {<b>From Duplicate 1 (<i>Estimating nanoparticle growth rates from size-dependent charged fractions: Analysis of new particle formation events in Mexico City</i> - Iida, Kenjiro; Stolzenburg, Mark R.; McMurry, Peter H.; Smith, James N.)<br/></b><br/><b>From Duplicate 1 (<i>Estimating nanoparticle growth rates from size-dependent charged fractions: Analysis of new particle formation events in Mexico City</i> - Iida, Kenjiro; Stolzenburg, Mark R.; McMurry, Peter H.; Smith, James N.)<br/></b><br/><b>From Duplicate 1 (<i>Estimating nanoparticle growth rates from size-dependent charged fractions: Analysis of new particle formation events in Mexico City</i> - Iida, K; Stolzenburg, M R; McMurry, P H; Smith, J N)<br/></b><br/>Cited References Count:66|AMER GEOPHYSICAL UNION|2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA|ISI Document Delivery No.:276QH<br/><br/><b>From Duplicate 2 (<i>Estimating nanoparticle growth rates from size-dependent charged fractions: Analysis of new particle formation events in Mexico City</i> - Iida, Kenjiro; Stolzenburg, Mark R.; McMurry, Peter H.; Smith, James N.)<br/></b><br/>Cited References Count:66|AMER GEOPHYSICAL UNION|2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA|ISI Document Delivery No.:276QH},
 private_publication = {false},
 abstract = {A method to estimate nanoparticle diameter growth rates (GR) during new particle formation (NPF) events from the measured dependence of charged fraction, f on size, D<inf>p</inf>, is introduced. The method is especially useful for observations during intense particle production rates, when the mode in the distribution of newly formed particles does not grow monotonically with time. This method assumes that the observed profile of f versus D<inf>p</inf> during the nucleation and growth period is controlled by condensational growth, ion-particle combination/ recombination, scavenging by preexisting particles, and coagulation among growing nanoparticles. Values of growth rates obtained by this method (GRf) agree well with independently obtained particle growth rates due to gas-to-particle conversion processes (GR<inf>PSD</inf>) during regional NPF events. The method was then applied to characterize the NPF events observed at Tecamac, Mexico. These growth rates were found to range from 15-40 nm/h, which is significantly higher than values reported for other urban areas. The production rates for I nm particles calculated from the estimated growth rates and measured Fuchs surface area (J<inf>1nm</inf> = 1900-3000 particles/cm<sup>3</sup> s) are comparable to those recently observed in New Delhi. Because critical nuclei are likely close to 1 nm in size, J<inf>1nm</inf> should provide a reasonable estimate for nucleation rates. Copyright 2008 by the American Geophysical Union.},
 bibtype = {article},
 author = {Iida, Kenjiro and Stolzenburg, Mark R. and McMurry, Peter H. and Smith, James N.},
 doi = {10.1029/2007JD009260},
 journal = {Journal of Geophysical Research Atmospheres},
 number = {5}
}

A method to estimate nanoparticle diameter growth rates (GR) during new particle formation (NPF) events from the measured dependence of charged fraction, f on size, Dp, is introduced. The method is especially useful for observations during intense particle production rates, when the mode in the distribution of newly formed particles does not grow monotonically with time. This method assumes that the observed profile of f versus Dp during the nucleation and growth period is controlled by condensational growth, ion-particle combination/ recombination, scavenging by preexisting particles, and coagulation among growing nanoparticles. Values of growth rates obtained by this method (GRf) agree well with independently obtained particle growth rates due to gas-to-particle conversion processes (GRPSD) during regional NPF events. The method was then applied to characterize the NPF events observed at Tecamac, Mexico. These growth rates were found to range from 15-40 nm/h, which is significantly higher than values reported for other urban areas. The production rates for I nm particles calculated from the estimated growth rates and measured Fuchs surface area (J1nm = 1900-3000 particles/cm³ s) are comparable to those recently observed in New Delhi. Because critical nuclei are likely close to 1 nm in size, J1nm should provide a reasonable estimate for nucleation rates. Copyright 2008 by the American Geophysical Union.

@article{
 title = {Mapping the operation of the DMT continuous flow CCN counter},
 type = {article},
 year = {2006},
 keywords = {CCN,DMT},
 pages = {242-254},
 volume = {40},
 websites = {http://dx.doi.org/10.1080/02786820500543290},
 id = {70265c92-dac3-384f-95e3-ba34aab367c2},
 created = {2016-07-07T17:20:28.000Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-11-02T20:28:32.081Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Lance2006},
 source_type = {Journal Article},
 language = {English},
 notes = {Cited References Count:21|TAYLOR & FRANCIS INC|325 CHESTNUT ST, SUITE 800, PHILADELPHIA, PA 19106 USA|ISI Document Delivery No.:017YQ},
 private_publication = {false},
 abstract = {This work thoroughly analyzes a new commercial instrument for measuring Cloud Condensation Nuclei (CCN), the Droplet Measurement Technologies Cylindrical Continuous-Flow Streamwise Thermal Gradient CCN Chamber (CFSTGC). This instrument can measure CCN concentrations at supersaturations from 0.06% to 3% (potentially up to 6%), at a 1 Hz sampling rate that is sufficient for airborne operation. Our analysis employs a fully coupled numerical flow model to simulate the water vapor supersaturation, temperature, velocity profiles and CCN growth in the CFSTGC for its entire range of operation (aerosol sample flow rates 0.25-2.0 L min - 1 , temperature differences 2-15 K and ambient pressures 100-1000 mb). The model was evaluated by comparing simulated instrument responses for calibration aerosol against actual measurements from an existing CCN instrument. The model was used to evaluate the CCN detection efficiency for a wide range of ambient pressures, flow rates, temperature gradients, and droplet growth kinetics. Simulations overestimate the instrument supersaturation when the thermal resistance across the walls of the flow chamber is not considered. We have developed a methodology to determine the thermal resistance and temperature drop across the wetted walls of the flow chamber, by combining simulations and calibration experiments. Finally, we provide parameterizations for determining the thermal resistance, the instrument supersaturation and the optimal detection threshold for the optical particle counter. Copyright © American Association for Aerosol Research.},
 bibtype = {article},
 author = {Lance, S. and Medina, J. and Smith, J. and Nenes, A.},
 doi = {10.1080/02786820500543290},
 journal = {Aerosol Science and Technology},
 number = {4}
}

This work thoroughly analyzes a new commercial instrument for measuring Cloud Condensation Nuclei (CCN), the Droplet Measurement Technologies Cylindrical Continuous-Flow Streamwise Thermal Gradient CCN Chamber (CFSTGC). This instrument can measure CCN concentrations at supersaturations from 0.06% to 3% (potentially up to 6%), at a 1 Hz sampling rate that is sufficient for airborne operation. Our analysis employs a fully coupled numerical flow model to simulate the water vapor supersaturation, temperature, velocity profiles and CCN growth in the CFSTGC for its entire range of operation (aerosol sample flow rates 0.25-2.0 L min - 1 , temperature differences 2-15 K and ambient pressures 100-1000 mb). The model was evaluated by comparing simulated instrument responses for calibration aerosol against actual measurements from an existing CCN instrument. The model was used to evaluate the CCN detection efficiency for a wide range of ambient pressures, flow rates, temperature gradients, and droplet growth kinetics. Simulations overestimate the instrument supersaturation when the thermal resistance across the walls of the flow chamber is not considered. We have developed a methodology to determine the thermal resistance and temperature drop across the wetted walls of the flow chamber, by combining simulations and calibration experiments. Finally, we provide parameterizations for determining the thermal resistance, the instrument supersaturation and the optimal detection threshold for the optical particle counter. Copyright © American Association for Aerosol Research.

@article{
 title = {Negative atmospheric ions and their potential role in ion-induced nucleation},
 type = {article},
 year = {2006},
 pages = {D04305},
 volume = {111},
 websites = {http://doi.wiley.com/10.1029/2005JD006568},
 id = {bbed9c9b-41af-31e9-8528-33ba4b90b53a},
 created = {2016-07-07T17:20:41.000Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-11-02T20:28:34.337Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Eisele2006},
 source_type = {Journal Article},
 language = {English},
 notes = {Cited References Count:40|AMER GEOPHYSICAL UNION|2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA|ISI Document Delivery No.:021EP},
 private_publication = {false},
 abstract = {Mass identified ion cluster distributions were measured under ambient atmospheric conditions and compared with model predictions based on laboratory ion cluster thermodynamics data. The results are shown from several days where atmospheric sulfur concentrations were high and thus ion-induced cluster growth was anticipated. Atmospheric gas phase sulfuric acid, temperature, relative humidity, SO<inf>2</inf>, mobility distributions of ions and small charged particles, and aerosol size distributions were also measured in support of the model calculations. The relative agreement of measurement and model for the first and second sulfuric acid clusters (HSO<inf>4</inf><sup>-</sup>(H<inf>2</inf> SO<inf>4</inf>)<inf>m</inf>) for m = 1 and 2 is quite good but suggests that sulfuric acid clustering may not occur at the collision rate. Clusters for higher in values were not observed, which is also consistent with model predictions for the conditions under which measurements were performed. The lack of both observed and predicted large ion clusters is also consistent with the independent measurements of ion mobility distributions and particle size distributions, which showed similar numbers of positively and negatively charged ultrafine particles, suggesting that neither positive nor negative ion-induced nucleation processes were likely to have contributed significantly to observed new particle formation rates during this study. The relatively low observed concentrations of the bisulfate ion also suggest that the processes leading to the first sulfuric acid/bisulfate cluster (HSO<inf>4</inf><sup>-</sup>H<inf>2</inf>SO<inf>4</inf>) may be more complicated than simple sulfuric acid clustering or exchange reactions. While nucleation was observed on some days, measurements suggest that ion-induced nucleation did not contribute significantly to new particle production or growth during these events. This does not rule out the possibility that ion-induced nucleation could contribute significantly to atmospheric new particle formation under very different atmosphere conditions such as in areas with much lower temperatures and higher ion concentrations. Copyright 2006 by the American Geophysical Union.},
 bibtype = {article},
 author = {Eisele, F. L. and Lovejoy, E. R. and Kosciuch, E. and Moore, K. F. and Mauldin, III L. and Smith, J. N. and McMurry, P. H. and Iida, Kenjiro},
 doi = {10.1029/2005JD006568},
 journal = {Journal of Geophysical Research Atmospheres},
 number = {4}
}

Mass identified ion cluster distributions were measured under ambient atmospheric conditions and compared with model predictions based on laboratory ion cluster thermodynamics data. The results are shown from several days where atmospheric sulfur concentrations were high and thus ion-induced cluster growth was anticipated. Atmospheric gas phase sulfuric acid, temperature, relative humidity, SO2, mobility distributions of ions and small charged particles, and aerosol size distributions were also measured in support of the model calculations. The relative agreement of measurement and model for the first and second sulfuric acid clusters (HSO4^-(H2 SO4)m) for m = 1 and 2 is quite good but suggests that sulfuric acid clustering may not occur at the collision rate. Clusters for higher in values were not observed, which is also consistent with model predictions for the conditions under which measurements were performed. The lack of both observed and predicted large ion clusters is also consistent with the independent measurements of ion mobility distributions and particle size distributions, which showed similar numbers of positively and negatively charged ultrafine particles, suggesting that neither positive nor negative ion-induced nucleation processes were likely to have contributed significantly to observed new particle formation rates during this study. The relatively low observed concentrations of the bisulfate ion also suggest that the processes leading to the first sulfuric acid/bisulfate cluster (HSO4^-H2SO4) may be more complicated than simple sulfuric acid clustering or exchange reactions. While nucleation was observed on some days, measurements suggest that ion-induced nucleation did not contribute significantly to new particle production or growth during these events. This does not rule out the possibility that ion-induced nucleation could contribute significantly to atmospheric new particle formation under very different atmosphere conditions such as in areas with much lower temperatures and higher ion concentrations. Copyright 2006 by the American Geophysical Union.

@article{
 title = {Coupling between land ecosystems and the atmospheric hydrologic cycle through biogenic aerosol pathways},
 type = {article},
 year = {2005},
 pages = {1738-1742},
 volume = {86},
 websites = {http://journals.ametsoc.org/doi/abs/10.1175/BAMS-86-12-1738},
 id = {15eef6fa-9109-3549-9870-2b2559893705},
 created = {2016-07-07T17:20:34.000Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-08-21T23:00:48.785Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Barth2005},
 source_type = {Journal Article},
 language = {English},
 notes = {Cited References Count:9|AMER METEOROLOGICAL SOC|45 BEACON ST, BOSTON, MA 02108-3693 USA|ISI Document Delivery No.:003CX},
 private_publication = {false},
 abstract = {Abstract No Abstract Available. No Abstract Available.},
 bibtype = {article},
 author = {Barth, Mary and McFadden, Joseph P. and Sun, Jielun and Wiedinmyer, Christine and Chuang, Patrick and Collins, Don and Griffin, Robert and Hannigan, Michael and Karl, Thomas and Kim, Si Wan and Lasher-Trapp, Sonia and Levis, Samuel and Litvak, Marcy and Mahowald, Natalie and Moore, Katharine and Nandi, Sreela and Nemitz, Eiko and Nenes, Athanasios and Potosnak, Mark and Raymond, Timothy M. and Smith, James and Still, Christopher and Stroud, Craig},
 doi = {10.1175/BAMS-86-12-1738},
 journal = {Bulletin of the American Meteorological Society},
 number = {12}
}

Abstract No Abstract Available. No Abstract Available.

@article{
 title = {A criterion for new particle formation in the sulfur-rich Atlanta atmosphere},
 type = {article},
 year = {2005},
 pages = {1-10},
 volume = {110},
 websites = {http://doi.wiley.com/10.1029/2005JD005901},
 id = {4f395d3b-36c9-3690-bdfd-78ab42d4be59},
 created = {2020-08-21T23:09:04.561Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-11-02T20:28:33.420Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {McMurry2005},
 source_type = {Journal Article},
 language = {English},
 notes = {<b>From Duplicate 1 (<i>A criterion for new particle formation in the sulfur-rich Atlanta atmosphere</i> - McMurry, P. H.; Fink, M.; Sakurai, H.; Stolzenburg, M. R.; Mauldin, R. L.; Smith, J.; Eisele, F.; Moore, K.; Sjostedt, S.; Tanner, D.; Huey, L. G.; Nowak, J. B.; Edgerton, E.; Voisin, D.; Mauldin, III L.; Smith, J.; Eisele, F.; Moore, K.; Sjostedt, S.; Tanner, D.; Huey, L. G.; Nowak, J. B.; Edgerton, E.; Voisin, D.)<br/></b><br/><b>From Duplicate 2 (<i>A criterion for new particle formation in the sulfur-rich Atlanta atmosphere</i> - McMurry, P. H.; Fink, M.; Sakurai, H.; Stolzenburg, M. R.; Mauldin, R. L.; Smith, J.; Eisele, F.; Moore, K.; Sjostedt, S.; Tanner, D.; Huey, L. G.; Nowak, J. B.; Edgerton, E.; Voisin, D.)<br/></b><br/>Cited References Count:49|AMER GEOPHYSICAL UNION|2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA|ISI Document Delivery No.:982MC},
 private_publication = {false},
 abstract = {A simple dimensionless parameter, L, is shown to determine whether or not new particle formation can occur in the atmosphere on a given day. The criterion accounts for the probability that clusters, formed by nucleation, will coagulate with preexisting particles before they grow to a detectable size. Data acquired in an intensive atmospheric measurement campaign in Atlanta, Georgia, during August 2002 (ANARChE) were used to test the validity of this criterion. Measurements included aerosol size distributions down to 3 nm, properties and composition of freshly nucleated particles, and concentrations of gases including ammonia and sulfuric acid. Nucleation and subsequent growth of particles at this site were often dominated by sulfuric acid. New particle formation was observed when L was less than ∼1 but not when L was greater than ∼1. Furthermore, new particle formation was only observed when sulfuric acid concentrations exceeded 5 × 10<sup>6</sup> cm<sup>-3</sup>. The data suggest that there was a positive association between concentrations of particles produced by nucleation and ammonia, but this was not shown definitively. Ammonia mixing ratios during this study were mostly in the 1 to 10 ppbv range. Copyright 2005 by the American Geophysical Union.},
 bibtype = {article},
 author = {McMurry, P. H. and Fink, M. and Sakurai, H. and Stolzenburg, M. R. and Mauldin, III L. and Smith, J. and Eisele, F. and Moore, K. and Sjostedt, S. and Tanner, D. and Huey, L. G. and Nowak, J. B. and Edgerton, E. and Voisin, D.},
 doi = {10.1029/2005JD005901},
 journal = {Journal of Geophysical Research Atmospheres},
 number = {22},
 keywords = {p36.pdf}
}

A simple dimensionless parameter, L, is shown to determine whether or not new particle formation can occur in the atmosphere on a given day. The criterion accounts for the probability that clusters, formed by nucleation, will coagulate with preexisting particles before they grow to a detectable size. Data acquired in an intensive atmospheric measurement campaign in Atlanta, Georgia, during August 2002 (ANARChE) were used to test the validity of this criterion. Measurements included aerosol size distributions down to 3 nm, properties and composition of freshly nucleated particles, and concentrations of gases including ammonia and sulfuric acid. Nucleation and subsequent growth of particles at this site were often dominated by sulfuric acid. New particle formation was observed when L was less than ∼1 but not when L was greater than ∼1. Furthermore, new particle formation was only observed when sulfuric acid concentrations exceeded 5 × 10⁶ cm^-3. The data suggest that there was a positive association between concentrations of particles produced by nucleation and ammonia, but this was not shown definitively. Ammonia mixing ratios during this study were mostly in the 1 to 10 ppbv range. Copyright 2005 by the American Geophysical Union.

@article{
 title = {Chemical composition of atmospheric nanoparticles during nucleation events in Atlanta},
 type = {article},
 year = {2005},
 pages = {1-13},
 volume = {110},
 websites = {http://doi.wiley.com/10.1029/2005JD005912},
 id = {7e303baa-1a8f-3480-99cd-798247778578},
 created = {2023-01-31T22:46:05.831Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:05.831Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Smith2005a},
 source_type = {Journal Article},
 language = {English},
 notes = {<b>From Duplicate 2 (<i>Chemical composition of atmospheric nanoparticles during nucleation events in Atlanta</i> - Smith, James N.; Moore, Katharine F.; Eisele, Fred L.; Voisin, Didier; Ghimire, Ajaya K.; Sakurai, Hiromu; McMurry, Peter H.)<br/></b><br/>Cited References Count:20|AMER GEOPHYSICAL UNION|2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA|ISI Document Delivery No.:985DI},
 private_publication = {false},
 abstract = {We report the first direct, in situ measurements of the chemical composition of size-segregated atmospheric nanoparticles in the 6-15 nm diameter range. These measurements were made of ambient aerosol directly following nucleation events in Atlanta, Georgia, during the 2002 Aerosol Nucleation and Real-time Characterization Experiment (ANARChE). The recently developed Thermal Desorption Chemical Ionization Mass Spectrometer (TDCIMS) was used to make these measurements and featured a new inlet that delivers mass of charged and size-segregated nanoparticles at sufficiently high rates to enable analysis at a typical time resolution of 10 min. Measurements in both the positive and negative ion spectra revealed that particles formed recently from nucleation events have enhanced concentrations of ammonium and sulfate and that to within the uncertainty of our measurements, ammonium sulfate could account for all of the sampled nanoparticle mass. No other compounds were detected in the particles during these events. Concurrent measurements of particle hygroscopicity and volatility, made using a Nanometer Tandem Differential Mobility Analyzer, support the conclusion that ammonium and sulfate are primary components of these newly formed particles. Copyright 2005 by the American Geophysical Union.},
 bibtype = {article},
 author = {Smith, James N. and Moore, Katharine F. and Eisele, Fred L. and Voisin, Didier and Ghimire, Ajaya K. and Sakurai, Hiromu and McMurry, Peter H.},
 doi = {10.1029/2005JD005912},
 journal = {Journal of Geophysical Research Atmospheres},
 number = {22}
}

We report the first direct, in situ measurements of the chemical composition of size-segregated atmospheric nanoparticles in the 6-15 nm diameter range. These measurements were made of ambient aerosol directly following nucleation events in Atlanta, Georgia, during the 2002 Aerosol Nucleation and Real-time Characterization Experiment (ANARChE). The recently developed Thermal Desorption Chemical Ionization Mass Spectrometer (TDCIMS) was used to make these measurements and featured a new inlet that delivers mass of charged and size-segregated nanoparticles at sufficiently high rates to enable analysis at a typical time resolution of 10 min. Measurements in both the positive and negative ion spectra revealed that particles formed recently from nucleation events have enhanced concentrations of ammonium and sulfate and that to within the uncertainty of our measurements, ammonium sulfate could account for all of the sampled nanoparticle mass. No other compounds were detected in the particles during these events. Concurrent measurements of particle hygroscopicity and volatility, made using a Nanometer Tandem Differential Mobility Analyzer, support the conclusion that ammonium and sulfate are primary components of these newly formed particles. Copyright 2005 by the American Geophysical Union.

@article{
 title = {Growth rates of freshly nucleated atmospheric particles in Atlanta},
 type = {article},
 year = {2005},
 keywords = {p35.pdf},
 pages = {1-10},
 volume = {110},
 websites = {http://doi.wiley.com/10.1029/2005JD005935},
 id = {a1ecfda9-539e-3a25-b399-688a72459f3e},
 created = {2023-01-31T22:46:14.969Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:14.969Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Stolzenburg2005a},
 source_type = {Journal Article},
 language = {English},
 notes = {<b>From Duplicate 1 (<i>Growth rates of freshly nucleated atmospheric particles in Atlanta</i> - Stolzenburg, Mark R.; McMurry, Peter H.; Sakurai, Hiromu; Smith, James N.; Mauldin, R. Lee; Eisele, Fred L.; Clement, Charles F.)<br/></b><br/><b>From Duplicate 1 (<i>Growth rates of freshly nucleated atmospheric particles in Atlanta</i> - Stolzenburg, Mark R.; McMurry, Peter H.; Sakurai, Hiromu; Smith, James N.; Mauldin, R. Lee; Eisele, Fred L.; Clement, Charles F.)<br/></b><br/>Cited References Count:25|AMER GEOPHYSICAL UNION|2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA|ISI Document Delivery No.:985DJ},
 private_publication = {false},
 abstract = {During the Atlanta ANARChE Study of July and August 2002, atmospheric aerosol size distributions from 3 to 2000 nm were measured continuously with 5-min resolution. Sulfuric acid vapor concentrations were also measured. During regional nucleation events these data showed the presence of a nucleation mode that grew at rates ranging from 3 to 20 nm h<sup>-1</sup>. In this paper we compare these measured modal growth rates with calculated rates that account for sulfuric acid condensation, intramodal coagulation of nucleation mode particles, and extramodal coagulation of nucleation mode particles with preexisting particles. Data collected during six time intervals were amenable to analysis. Calculated and measured growth rates were in reasonable agreement for the four events that involved growth below 40 nm (ratios of measured to calculated growth rates = 1.0, 2.1, 0.68, 0.60). Two of the three afternoon events involved growth above 40 nm, and in these cases, measured rates substantially exceeded calculated rates by factors of four to five, suggesting that our model did not account for all growth processes. We also compared observed rates of change in nucleation mode number concentration with calculated coagulation rates during these six time intervals. During the sub-40 nm growth events, particle concentrations changed at rates that were significantly below calculated coagulation rates. In two of these cases, particle concentrations increased during the growth period, suggesting that a source of particles was present. Measured size distributions suggest that particle production by nucleation continued during these events and contributed to this discrepancy. Concentrations during the super-40 nm events decreased at rates that exceeded calculated coagulation rates. Copyright 2005 by the American Geophysical Union.},
 bibtype = {article},
 author = {Stolzenburg, Mark R. and McMurry, Peter H. and Sakurai, Hiromu and Smith, James N. and Mauldin, R. Lee and Eisele, Fred L. and Clement, Charles F.},
 doi = {10.1029/2005JD005935},
 journal = {Journal of Geophysical Research Atmospheres},
 number = {22}
}

During the Atlanta ANARChE Study of July and August 2002, atmospheric aerosol size distributions from 3 to 2000 nm were measured continuously with 5-min resolution. Sulfuric acid vapor concentrations were also measured. During regional nucleation events these data showed the presence of a nucleation mode that grew at rates ranging from 3 to 20 nm h^-1. In this paper we compare these measured modal growth rates with calculated rates that account for sulfuric acid condensation, intramodal coagulation of nucleation mode particles, and extramodal coagulation of nucleation mode particles with preexisting particles. Data collected during six time intervals were amenable to analysis. Calculated and measured growth rates were in reasonable agreement for the four events that involved growth below 40 nm (ratios of measured to calculated growth rates = 1.0, 2.1, 0.68, 0.60). Two of the three afternoon events involved growth above 40 nm, and in these cases, measured rates substantially exceeded calculated rates by factors of four to five, suggesting that our model did not account for all growth processes. We also compared observed rates of change in nucleation mode number concentration with calculated coagulation rates during these six time intervals. During the sub-40 nm growth events, particle concentrations changed at rates that were significantly below calculated coagulation rates. In two of these cases, particle concentrations increased during the growth period, suggesting that a source of particles was present. Measured size distributions suggest that particle production by nucleation continued during these events and contributed to this discrepancy. Concentrations during the super-40 nm events decreased at rates that exceeded calculated coagulation rates. Copyright 2005 by the American Geophysical Union.

@article{
 title = {Multi-component chemical analysis of gas mixtures using a continuously tuneable lidar system},
 type = {article},
 year = {2004},
 pages = {525-530},
 volume = {79},
 websites = {http://link.springer.com/10.1007/s00340-004-1565-8},
 month = {9},
 day = {1},
 id = {c7c4289f-4af3-3278-a71a-29a39375bc9d},
 created = {2016-07-07T17:20:54.000Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-11-02T20:28:35.100Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Weibring2004},
 source_type = {Journal Article},
 language = {English},
 notes = {Cited References Count:13|SPRINGER|233 SPRING STREET, NEW YORK, NY 10013 USA|ISI Document Delivery No.:845QV},
 private_publication = {false},
 abstract = {Differential absorption lidar (DIAL) measurements are usually made on single compounds by alternately switching the wavelength between on and off a resonance line. The selection of more than two wavelengths is a mathematical necessity for simultaneous measurement of multiple species or for resolving interference effects between a compound of interest and a background gas such as water vapour or carbon dioxide. This is especially true in the mid-IR region, where many hydrocarbon compounds have important spectral features. We present a method for remote measurement of gas mixtures in the mid-IR region based on a newly developed fast-switching, frequency-agile optical parametric oscillator lidar transmitter. A multivariate statistical procedure has also been applied for this system, which combines a genetic algorithm for wavelength selection with a partial least squares method for identifying individual compounds from their combined absorption spectrum. A calibration transfer is performed for compounds of interest using reference spectra from an absorption spectra database. Both indoor absorption cell measurements and outdoor remote range resolved measurements of hydrocarbon mixtures were performed to explore the performance of the method.},
 bibtype = {article},
 author = {Weibring, P. and Abrahamsson, C. and Sjöholm, M. and Smith, J. N. and Edner, H. and Svanberg, S.},
 doi = {10.1007/s00340-004-1565-8},
 journal = {Applied Physics B: Lasers and Optics},
 number = {4}
}

Differential absorption lidar (DIAL) measurements are usually made on single compounds by alternately switching the wavelength between on and off a resonance line. The selection of more than two wavelengths is a mathematical necessity for simultaneous measurement of multiple species or for resolving interference effects between a compound of interest and a background gas such as water vapour or carbon dioxide. This is especially true in the mid-IR region, where many hydrocarbon compounds have important spectral features. We present a method for remote measurement of gas mixtures in the mid-IR region based on a newly developed fast-switching, frequency-agile optical parametric oscillator lidar transmitter. A multivariate statistical procedure has also been applied for this system, which combines a genetic algorithm for wavelength selection with a partial least squares method for identifying individual compounds from their combined absorption spectrum. A calibration transfer is performed for compounds of interest using reference spectra from an absorption spectra database. Both indoor absorption cell measurements and outdoor remote range resolved measurements of hydrocarbon mixtures were performed to explore the performance of the method.

@article{
 title = {Measurements of Mexico City nanoparticle size distributions: Observations of new particle formation and growth},
 type = {article},
 year = {2004},
 volume = {31},
 websites = {http://onlinelibrary.wiley.com/doi/10.1029/2004GL019483/full},
 id = {afc04afe-abc1-3ed4-a525-49fbff2e514d},
 created = {2016-07-07T17:21:10.000Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-08-21T23:00:48.446Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Dunn2004},
 source_type = {Journal Article},
 language = {English},
 notes = {Cited References Count:18|AMER GEOPHYSICAL UNION|2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA|ISI Document Delivery No.:823KE},
 private_publication = {false},
 abstract = {Continuous measurements of the size distribution of atmospheric aerosol in the 3-48 nm diameter range were performed in the Mexico City metropolitan area. These measurements were made during the period 10-20 April 2003 at a ground-based, mountain pass site in the southeast comer of the Mexico City Federal District and during the period 2-11 May 2003 at the CENICA site located near the city center. The objectives of this work were to determine the frequency of new particle formation and to characterize the atmospheric chemical and meteorological conditions that lead to these events. Several new particle formation events were recorded during the study. Events observed in the mountain pass correlate with northerly winds and elevated levels of sulfur dioxide in the mid-morning while events observed in the city correlate with elevated concentrations of sulfur dioxide and low particulate matter mass concentrations in the afternoon hours. Copyright 2004 by the American Geophysical Union.},
 bibtype = {article},
 author = {Dunn, Matthew J. and Jiménez, José Luis and Baumgardner, Darrel and Castro, Telma and McMurry, Peter H. and Smith, James N.},
 doi = {10.1029/2004GL019483},
 journal = {Geophysical Research Letters},
 number = {10}
}

Continuous measurements of the size distribution of atmospheric aerosol in the 3-48 nm diameter range were performed in the Mexico City metropolitan area. These measurements were made during the period 10-20 April 2003 at a ground-based, mountain pass site in the southeast comer of the Mexico City Federal District and during the period 2-11 May 2003 at the CENICA site located near the city center. The objectives of this work were to determine the frequency of new particle formation and to characterize the atmospheric chemical and meteorological conditions that lead to these events. Several new particle formation events were recorded during the study. Events observed in the mountain pass correlate with northerly winds and elevated levels of sulfur dioxide in the mid-morning while events observed in the city correlate with elevated concentrations of sulfur dioxide and low particulate matter mass concentrations in the afternoon hours. Copyright 2004 by the American Geophysical Union.

@article{
 title = {Development and testing of a frequency-agile optical parametric oscillator system for differential absorption lidar},
 type = {article},
 year = {2003},
 pages = {4478-4484},
 volume = {74},
 websites = {http://aip.scitation.org/doi/10.1063/1.1599065},
 month = {10},
 id = {3c607a0c-c148-3061-9a83-8dc5c423ade5},
 created = {2016-07-07T17:20:54.000Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-11-02T20:28:35.385Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Weibring2003},
 source_type = {Journal Article},
 language = {English},
 notes = {Cited References Count:15|AMER INST PHYSICS|CIRCULATION & FULFILLMENT DIV, 2 HUNTINGTON QUADRANGLE, STE 1 N O 1, MELVILLE, NY 11747-4501 USA|ISI Document Delivery No.:730RW},
 private_publication = {false},
 abstract = {An all-solid-state fast-tuning lidar transmitter for range- and temporally resolved atmospheric gas concentration measurements has been developed and thoroughly tested. The instrument is based on a commercial optical parametric oscillator (OPO) laser system, which has been redesigned with piezoelectric transducers mounted on the wavelength-tuning mirror and on the crystal angle tuning element in the OPO. Piezoelectric transducers similarly control a frequency-mixing stage and doubling stage, which have been incorporated to extend system capabilities to the mid-IR and UV regions. The construction allows the system to be tuned to any wavelength, in any order, in the range of the piezoelectric transducers on a shot-to-shot basis. This extends the measurement capabilities far beyond the two-wavelength differential absorption lidar method and enables simultaneous measurements of several gases. The system performance in terms of wavelength, linewidth, and power stability is monitored in real time by an &#xe9;talon-based wave meter and gas cells. The tests showed that the system was able to produce radiation in the 220&#x2013;4300-nm-wavelength region, with an average linewidth better than <equation>0.2<span style="font-size: .5em;">&nbsp;</span><font face='roman'>cm</font><sup>-1</sup></equation> and a shot-to-shot tunability up to <equation>160<span style="font-size: .5em;">&nbsp;</span><font face='roman'>cm</font><sup>-1</sup></equation> within 20 ms. The utility of real-time linewidth and wavelength measurements is demonstrated by the ability to identify occasional poor quality laser shots and disregard these measurements. Also, absorption cell measurements of methane and mercury demonstrate the performance in obtaining stable wavelength and linewidth during rapid scans in the mid-IR and UV regions. &#xa9; 2003 American Institute of Physics.},
 bibtype = {article},
 author = {Weibring, P. and Smith, J. N. and Edner, H. and Svanberg, S.},
 doi = {10.1063/1.1599065},
 journal = {Review of Scientific Instruments},
 number = {10}
}

An all-solid-state fast-tuning lidar transmitter for range- and temporally resolved atmospheric gas concentration measurements has been developed and thoroughly tested. The instrument is based on a commercial optical parametric oscillator (OPO) laser system, which has been redesigned with piezoelectric transducers mounted on the wavelength-tuning mirror and on the crystal angle tuning element in the OPO. Piezoelectric transducers similarly control a frequency-mixing stage and doubling stage, which have been incorporated to extend system capabilities to the mid-IR and UV regions. The construction allows the system to be tuned to any wavelength, in any order, in the range of the piezoelectric transducers on a shot-to-shot basis. This extends the measurement capabilities far beyond the two-wavelength differential absorption lidar method and enables simultaneous measurements of several gases. The system performance in terms of wavelength, linewidth, and power stability is monitored in real time by an étalon-based wave meter and gas cells. The tests showed that the system was able to produce radiation in the 220–4300-nm-wavelength region, with an average linewidth better than 0.2 cm^-1 and a shot-to-shot tunability up to 160 cm^-1 within 20 ms. The utility of real-time linewidth and wavelength measurements is demonstrated by the ability to identify occasional poor quality laser shots and disregard these measurements. Also, absorption cell measurements of methane and mercury demonstrate the performance in obtaining stable wavelength and linewidth during rapid scans in the mid-IR and UV regions. © 2003 American Institute of Physics.

@article{
 title = {Thermal desorption chemical ionization mass spectrometer for ultrafine particle chemical composition},
 type = {article},
 year = {2003},
 pages = {471-475},
 volume = {37},
 websites = {http://www.tandfonline.com/doi/abs/10.1080/02786820300959},
 id = {fb731cee-e27d-39bc-aff6-a99bfa276be4},
 created = {2023-01-31T22:46:13.777Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:13.777Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Voisin2003},
 source_type = {Journal Article},
 private_publication = {false},
 abstract = {A thermal desorption chemical ionization mass spectrometer has been developed for real time, quantitative chemical analysis of ultrafine particles. The technique combines recently developed nanoparticle separation and collection techniques with highly sensitive chemical analysis provided by selected ion chemical ionization mass spectrometry. Sensitivity tests using laboratorygenerated ammonium sulfate particles in the diameter range 10-16 nm show that sulfate and ammonium can be quantified with as little as 1 pg of collected aerosol mass. Such sensitivity makes this instrument suitable for real time measurements of the chemical composition of sub-10 nm particles reported recently from nucleation events.},
 bibtype = {article},
 author = {Voisin, Didier and Smith, J. N. and Sakurai, H. and McMurry, P. H. and Eisele, F. L.},
 doi = {10.1080/02786820300959},
 journal = {Aerosol Science and Technology},
 number = {6},
 keywords = {P521.PDF}
}

A thermal desorption chemical ionization mass spectrometer has been developed for real time, quantitative chemical analysis of ultrafine particles. The technique combines recently developed nanoparticle separation and collection techniques with highly sensitive chemical analysis provided by selected ion chemical ionization mass spectrometry. Sensitivity tests using laboratorygenerated ammonium sulfate particles in the diameter range 10-16 nm show that sulfate and ammonium can be quantified with as little as 1 pg of collected aerosol mass. Such sensitivity makes this instrument suitable for real time measurements of the chemical composition of sub-10 nm particles reported recently from nucleation events.

@article{
 title = {Droplet evaporation and discharge dynamics in electrospray ionization},
 type = {article},
 year = {2002},
 pages = {9957-9967},
 volume = {106},
 websites = {http://pubs.acs.org/doi/abs/10.1021/jp025723e},
 month = {10},
 publisher = {American Chemical Society},
 day = {1},
 id = {b0e6aa42-dd7b-32a9-8516-6303585dd303},
 created = {2023-01-31T22:46:15.440Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:15.440Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Smith2002},
 source_type = {JOUR},
 language = {English},
 notes = {<b>From Duplicate 1 (<i>Droplet evaporation and discharge dynamics in electrospray ionization</i> - Smith, James N.; Flagan, Richard C.; Beauchamp, J. L.)<br/></b><br/><b>From Duplicate 1 (<i>Droplet evaporation and discharge dynamics in electrospray ionization</i> - Smith, J N; Flagan, R C; Beauchamp, J L)<br/></b><br/>Cited References Count:53|AMER CHEMICAL SOC|1155 16TH ST, NW, WASHINGTON, DC 20036 USA|ISI Document Delivery No.:607LA},
 private_publication = {false},
 abstract = {We present measurements of the distributions of droplet size and charge along with, for selected droplets, the variation of droplet size and charge with time for electrosprays of methanol, acetonitrile, and water, as well as for methanol at different polarities and electrolyte concentrations. These measurements are performed using a new technique for measuring droplet size and charge that uses phase Doppler interferometry for obtaining droplet size and inferring droplet charge from comparison of measured and calculated droplet mobility in a constant electric field. For selected droplets, multiple measurements of the size and charge are performed by repeated reversal of the drift field. This "ping-pong" experiment tracks droplet size and charge for loss of up to 99.9% of the initial droplet volume. We observe that droplet instability, referred to as a discharge event, mainly occurs near or above the Rayleigh limit of charge, resulting in a charge loss of 15-20% for methanol and acetonitrile and 20-40% in the case of water. Each discharge event is accompanied by a small mass loss, and droplet size evolution is dominated by evaporation. Discharge dynamics for negatively charged droplets are similar to those observed for positively charged droplets. The addition of up to 10-4 M of NaCl to the solution does not significantly alter discharge dynamics. Measured size-charge correlations for droplets from electrosprays of methanol at low electrolyte concentrations (<10-5 M), and to a lesser degree acetonitrile with similar electrolyte levels, fall into discrete groupings of size and charge that can be attributed to an initially monodisperse distribution of size and charge, followed by discharge events in which a nearly constant fractional charge loss occurs as a result of the Rayleigh instability.},
 bibtype = {article},
 author = {Smith, James N. and Flagan, Richard C. and Beauchamp, J. L.},
 doi = {10.1021/jp025723e},
 journal = {Journal of Physical Chemistry A},
 number = {42}
}

We present measurements of the distributions of droplet size and charge along with, for selected droplets, the variation of droplet size and charge with time for electrosprays of methanol, acetonitrile, and water, as well as for methanol at different polarities and electrolyte concentrations. These measurements are performed using a new technique for measuring droplet size and charge that uses phase Doppler interferometry for obtaining droplet size and inferring droplet charge from comparison of measured and calculated droplet mobility in a constant electric field. For selected droplets, multiple measurements of the size and charge are performed by repeated reversal of the drift field. This "ping-pong" experiment tracks droplet size and charge for loss of up to 99.9% of the initial droplet volume. We observe that droplet instability, referred to as a discharge event, mainly occurs near or above the Rayleigh limit of charge, resulting in a charge loss of 15-20% for methanol and acetonitrile and 20-40% in the case of water. Each discharge event is accompanied by a small mass loss, and droplet size evolution is dominated by evaporation. Discharge dynamics for negatively charged droplets are similar to those observed for positively charged droplets. The addition of up to 10-4 M of NaCl to the solution does not significantly alter discharge dynamics. Measured size-charge correlations for droplets from electrosprays of methanol at low electrolyte concentrations (<10-5 M), and to a lesser degree acetonitrile with similar electrolyte levels, fall into discrete groupings of size and charge that can be attributed to an initially monodisperse distribution of size and charge, followed by discharge events in which a nearly constant fractional charge loss occurs as a result of the Rayleigh instability.

@article{
 title = {Design of a CCN instrument for airborne measurement},
 type = {article},
 year = {2000},
 pages = {1005-1019},
 volume = {17},
 websites = {http://journals.ametsoc.org/doi/abs/10.1175/1520-0426(2000)017%3C1005:DOACIF%3E2.0.CO;2},
 month = {8},
 id = {2ec5b2a0-8a07-3673-bb39-b2be30f12dfd},
 created = {2016-07-07T17:21:12.000Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-11-02T20:28:32.821Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Chuang2000},
 source_type = {Journal Article},
 language = {English},
 notes = {Cited References Count:30|AMER METEOROLOGICAL SOC|45 BEACON ST, BOSTON, MA 02108-3693 USA|ISI Document Delivery No.:353GN},
 private_publication = {false},
 abstract = {A new instrument for measuring cloud condensation nuclei (CCN) on board small aircraft is described. Small aircraft are attractive mainly because they are less costly, but they require instruments that are designed for minimum weight, volume, and power consumption; that are robust; and that are capable of autonomous operation and making measurements at a frequency appropriate for aircraft speeds. The instrument design combines the streamwise gradient technique previously reported by J. G. Hudson, and the alternating gradient condensation nuclei counter described by W. A. Hoppel et al. Field and laboratory measurements, and modeling studies show that this combination exhibits poor sensitivity for the measurement of CCN spectra; for the climatically important range of critical supersaturations, 0.03%-1%, the measured variable, droplet diameter, varies only by 30%. The ability to resolve CCN spectra using this method is therefore in question. Studies of this instrument in a fixed supersaturation mode show that it can measure CCN at a single supersaturation in the range of 0.1%-2%. Calibration and testing of the instrument in this mode is described. The instrument is capable of making accurate, high-frequency (>0.1 Hz) measurements of CCN at a fixed supersaturation, while satisfying the constraints for small aircraft.},
 bibtype = {article},
 author = {Chuang, P. Y. and Nenes, A. and Smith, J. N. and Flagan, R. C. and Seinfeld, J. H.},
 doi = {10.1175/1520-0426(2000)017<1005:DOACIF>2.0.CO;2},
 journal = {Journal of Atmospheric and Oceanic Technology},
 number = {8}
}

A new instrument for measuring cloud condensation nuclei (CCN) on board small aircraft is described. Small aircraft are attractive mainly because they are less costly, but they require instruments that are designed for minimum weight, volume, and power consumption; that are robust; and that are capable of autonomous operation and making measurements at a frequency appropriate for aircraft speeds. The instrument design combines the streamwise gradient technique previously reported by J. G. Hudson, and the alternating gradient condensation nuclei counter described by W. A. Hoppel et al. Field and laboratory measurements, and modeling studies show that this combination exhibits poor sensitivity for the measurement of CCN spectra; for the climatically important range of critical supersaturations, 0.03%-1%, the measured variable, droplet diameter, varies only by 30%. The ability to resolve CCN spectra using this method is therefore in question. Studies of this instrument in a fixed supersaturation mode show that it can measure CCN at a single supersaturation in the range of 0.1%-2%. Calibration and testing of the instrument in this mode is described. The instrument is capable of making accurate, high-frequency (>0.1 Hz) measurements of CCN at a fixed supersaturation, while satisfying the constraints for small aircraft.

@article{
 title = {Atmospheric oxidation mechanism of n-butane: The fate of alkoxy radicals},
 type = {article},
 year = {1997},
 pages = {4392-4401},
 volume = {101},
 websites = {http://pubs.acs.org/doi/abs/10.1021/jp970212r},
 month = {6},
 id = {24570ac1-5723-3f5a-8191-c133cadabfdc},
 created = {2023-01-31T22:46:15.196Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2023-01-31T22:46:15.196Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Jungkamp1997},
 source_type = {Journal Article},
 language = {English},
 notes = {<b>From Duplicate 1 (<i>Atmospheric oxidation mechanism of n-butane: The fate of alkoxy radicals</i> - Jungkamp, Tim P.W.; Smith, James N.; Seinfeld, John H.)<br/></b><br/><b>From Duplicate 2 (<i>Atmospheric oxidation mechanism of n-butane: The fate of alkoxy radicals</i> - Jungkamp, Tim P.W.; Smith, James N.; Seinfeld, John H.)<br/></b><br/>Cited References Count:39|AMER CHEMICAL SOC|1155 16TH ST, NW, WASHINGTON, DC 20036|ISI Document Delivery No.:XD906<br/><br/><b>From Duplicate 2 (<i>Atmospheric oxidation mechanism of n-butane: The fate of alkoxy radicals</i> - Jungkamp, Tim P.W.; Smith, James N.; Seinfeld, John H.)<br/></b><br/>Cited References Count:39|AMER CHEMICAL SOC|1155 16TH ST, NW, WASHINGTON, DC 20036|ISI Document Delivery No.:XD906},
 private_publication = {false},
 abstract = {The atmospheric oxidation mechanism of n-butane is investigated by means of density functional theory and ab initio calculations. Calculation of energies of reactants, transition states, and stable intermediates predicts the detailed pathways leading to experimentally observed products of n-butane oxidation. Also serving as a model system for the oxidation of larger alkanes, quantitative information is obtained for elementary reaction steps that heretofore have been subject to speculation. Complete basis set model chemistries CBS-4 and CBS-q were used with B3LYP/6-31G(d,p) optimized geometries to calculate energies of over 70 stable species and transition states. Energies based on density functional theory were obtained at the B3LYP/6-311+G-(3df,2p)//B3LYP/6-31G(d,p) level of theory. The principal pathway following formation of the 1-butyl radical from hydroxyl (OH) attack on n-butane is found to be 1,5-H shift of the 1-butoxy radical. After conversion to the δ-hydroxy-1-butoxy radical, another 1,5-H shift is expected to be the primary route to 4-hydroxy-1-butanal. 4-Hydroperoxy-1-butanal can be formed after 1,6-H shift in chemically activated 4-hydroxy-1-butylperoxy radicals. Whereas β-scission in 1-butoxy is an endothermic process, fragmentation of 2-butoxy into C2H5 and CH3CHO is predicted to be the major degradation pathway of the secondary butyl radicals.},
 bibtype = {article},
 author = {Jungkamp, Tim P.W. and Smith, James N. and Seinfeld, John H.},
 doi = {10.1021/jp970212r},
 journal = {Journal of Physical Chemistry A},
 number = {24}
}

The atmospheric oxidation mechanism of n-butane is investigated by means of density functional theory and ab initio calculations. Calculation of energies of reactants, transition states, and stable intermediates predicts the detailed pathways leading to experimentally observed products of n-butane oxidation. Also serving as a model system for the oxidation of larger alkanes, quantitative information is obtained for elementary reaction steps that heretofore have been subject to speculation. Complete basis set model chemistries CBS-4 and CBS-q were used with B3LYP/6-31G(d,p) optimized geometries to calculate energies of over 70 stable species and transition states. Energies based on density functional theory were obtained at the B3LYP/6-311+G-(3df,2p)//B3LYP/6-31G(d,p) level of theory. The principal pathway following formation of the 1-butyl radical from hydroxyl (OH) attack on n-butane is found to be 1,5-H shift of the 1-butoxy radical. After conversion to the δ-hydroxy-1-butoxy radical, another 1,5-H shift is expected to be the primary route to 4-hydroxy-1-butanal. 4-Hydroperoxy-1-butanal can be formed after 1,6-H shift in chemically activated 4-hydroxy-1-butylperoxy radicals. Whereas β-scission in 1-butoxy is an endothermic process, fragmentation of 2-butoxy into C2H5 and CH3CHO is predicted to be the major degradation pathway of the secondary butyl radicals.

@article{
 title = {Mechanism of atmospheric photooxidation of aromatics: A theoretical study},
 type = {article},
 year = {1996},
 pages = {10967-10980},
 volume = {100},
 websites = {http://pubs.acs.org/doi/abs/10.1021/jp952935l},
 id = {13a3de8c-ab6f-3314-91b1-b502bccad566},
 created = {2016-07-07T17:21:13.000Z},
 file_attached = {false},
 profile_id = {2e2b0bf1-6573-3fd8-8628-55d1dc39fe31},
 last_modified = {2020-08-21T23:00:49.945Z},
 read = {false},
 starred = {false},
 authored = {true},
 confirmed = {true},
 hidden = {false},
 citation_key = {Andino1996},
 source_type = {Journal Article},
 language = {English},
 notes = {Cited References Count:30|AMER CHEMICAL SOC|1155 16TH ST, NW, WASHINGTON, DC 20036|ISI Document Delivery No.:UU477},
 private_publication = {false},
 abstract = {The mechanisms of atmospheric photooxidation of aromatic compounds are of seminal importance in the chemistry of the urban and regional atmosphere. It has been difficult to experimentally account for the full spectrum of oxidation products in laboratory studies. In an effort to fully elucidate the atmospheric reaction pathways for the aromatic-OH reaction, we have conducted theoretical calculations on aromatic intermediates. Energies have been determined for these intermediates by using semiempirical UHF/PM3 geometry optimizations combined with ab initio calculations using density functional theory (DFT). A hybrid DFT model, the Becke3 parameter function with the nonlocal correlation function of Lee, Yang, and Parr, was used in conjunction with the 6-31G(d,p) basis set to study the intermediate structures. Full mechanisms for the OH-initiated photooxidation of toluene, m-xylene, p-xylene, 1,2,4-trimethylbenzene, and m-ethyltoluene are developed. The lowest energy intermediates have been determined, and predicted products from these structures are compared to available experimental product data. These studies serve to refine proposed mechanisms currently available for toluene, m-xylene, and p-xylene, while providing new information on the 1,2,4-trimethylbenzene and m-ethyltoluene reaction pathways. © 1996 American Chemical Society.},
 bibtype = {article},
 author = {Andino, Jean M. and Smith, James N. and Flagan, Richard C. and Goddard, William A. and Seinfeld, John H.},
 doi = {10.1021/jp952935l},
 journal = {Journal of Physical Chemistry},
 number = {26}
}

The mechanisms of atmospheric photooxidation of aromatic compounds are of seminal importance in the chemistry of the urban and regional atmosphere. It has been difficult to experimentally account for the full spectrum of oxidation products in laboratory studies. In an effort to fully elucidate the atmospheric reaction pathways for the aromatic-OH reaction, we have conducted theoretical calculations on aromatic intermediates. Energies have been determined for these intermediates by using semiempirical UHF/PM3 geometry optimizations combined with ab initio calculations using density functional theory (DFT). A hybrid DFT model, the Becke3 parameter function with the nonlocal correlation function of Lee, Yang, and Parr, was used in conjunction with the 6-31G(d,p) basis set to study the intermediate structures. Full mechanisms for the OH-initiated photooxidation of toluene, m-xylene, p-xylene, 1,2,4-trimethylbenzene, and m-ethyltoluene are developed. The lowest energy intermediates have been determined, and predicted products from these structures are compared to available experimental product data. These studies serve to refine proposed mechanisms currently available for toluene, m-xylene, and p-xylene, while providing new information on the 1,2,4-trimethylbenzene and m-ethyltoluene reaction pathways. © 1996 American Chemical Society.