Gas phase formation of extremely oxidized pinene reaction products in chamber and ambient air. Ehn, M., Kleist, E., Junninen, H., Petäjä, T., Lönn, G., Schobesberger, S., Dal Maso, M., Trimborn, A., Kulmala, M., Worsnop, D., R., Wahner, A., Wildt, J., Mentel, T., F., Petaja, T., Lonn, G., Schobesberger, S., Dal Maso, M., Trimborn, A., Kulmala, M., Worsnop, D., R., Wahner, A., Wildt, J., & Mentel, T., F. Atmospheric Chemistry and Physics, 12(11):5113-5127, 6, 2012.
Gas phase formation of extremely oxidized pinene reaction products in chamber and ambient air [pdf]Paper  Gas phase formation of extremely oxidized pinene reaction products in chamber and ambient air [link]Website  abstract   bibtex   
High molecular weight (300-650 Da) naturally charged negative ions have previously been observed at a boreal forest site in Hyytiala, Finland. The long-term measurements conducted in this work showed that these ions are observed practically every night between spring and autumn in Hyytiala. The ambient mass spectral patterns could be reproduced in striking detail during additional measurements of alpha-pinene (C10H16) oxidation at low-OH conditions in the Julich Plant Atmosphere Chamber (JPAC). The ions were identified as clusters of the nitrate ion (NO3-) and alpha-pinene oxidation products reaching oxygen to carbon ratios of 0.7-1.3, while retaining most of the initial ten carbon atoms. Attributing the ions to clusters instead of single molecules was based on additional observations of the same extremely oxidized organics in clusters with HSO4- (Hyytiala) and C3F5O2- (JPAC). The most abundant products in the ion spectra were identified as C10H14O7, C10H14O9, C10H16O9, and C10H14O11. The mechanism responsible for forming these molecules is still not clear, but the initial reaction is most likely ozone attack at the double bond, as the ions are mainly observed under dark conditions. beta-pinene also formed highly oxidized products under the same conditions, but less efficiently, and mainly C-9 compounds which were not observed in Hyytiala, where beta-pinene on average is 4-5 times less abundant than alpha-pinene. Further, to explain the high O/C together with the relatively high H/C, we propose that geminal diols and/or hydroperoxide groups may be important. We estimate that the night-time concentration of the sum of the neutral extremely oxidized products is on the order of 0.1-1 ppt (similar to 10(6)-10(7) molec cm(-3)). This is in a similar range as the amount of gaseous H2SO4 in Hyytiala during day-time. As these highly oxidized organics are roughly 3 times heavier, likely with extremely low vapor pressures, their role in the initial steps of new aerosol particle formation and growth may be important and needs to be explored in more detail in the future.
@article{
 title = {Gas phase formation of extremely oxidized pinene reaction products in chamber and ambient air},
 type = {article},
 year = {2012},
 identifiers = {[object Object]},
 keywords = {alpha-pinene/o-3 reaction,atmospheric conditions,boreal forest,galactic cosmic-rays,particle formation,secondary organic aerosol,smear-ii,sulfuric-acid,trap mass-spectrometry,tropospheric degradation},
 pages = {5113-5127},
 volume = {12},
 websites = {http://www.atmos-chem-phys.net/12/5113/2012/},
 month = {6},
 day = {11},
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 language = {English},
 abstract = {High molecular weight (300-650 Da) naturally charged negative ions have previously been observed at a boreal forest site in Hyytiala, Finland. The long-term measurements conducted in this work showed that these ions are observed practically every night between spring and autumn in Hyytiala. The ambient mass spectral patterns could be reproduced in striking detail during additional measurements of alpha-pinene (C10H16) oxidation at low-OH conditions in the Julich Plant Atmosphere Chamber (JPAC). The ions were identified as clusters of the nitrate ion (NO3-) and alpha-pinene oxidation products reaching oxygen to carbon ratios of 0.7-1.3, while retaining most of the initial ten carbon atoms. Attributing the ions to clusters instead of single molecules was based on additional observations of the same extremely oxidized organics in clusters with HSO4- (Hyytiala) and C3F5O2- (JPAC). The most abundant products in the ion spectra were identified as C10H14O7, C10H14O9, C10H16O9, and C10H14O11. The mechanism responsible for forming these molecules is still not clear, but the initial reaction is most likely ozone attack at the double bond, as the ions are mainly observed under dark conditions. beta-pinene also formed highly oxidized products under the same conditions, but less efficiently, and mainly C-9 compounds which were not observed in Hyytiala, where beta-pinene on average is 4-5 times less abundant than alpha-pinene. Further, to explain the high O/C together with the relatively high H/C, we propose that geminal diols and/or hydroperoxide groups may be important. We estimate that the night-time concentration of the sum of the neutral extremely oxidized products is on the order of 0.1-1 ppt (similar to 10(6)-10(7) molec cm(-3)). This is in a similar range as the amount of gaseous H2SO4 in Hyytiala during day-time. As these highly oxidized organics are roughly 3 times heavier, likely with extremely low vapor pressures, their role in the initial steps of new aerosol particle formation and growth may be important and needs to be explored in more detail in the future.},
 bibtype = {article},
 author = {Ehn, M. and Kleist, E. and Junninen, H. and Petäjä, T. and Lönn, G. and Schobesberger, S. and Dal Maso, M. and Trimborn, A. and Kulmala, M. and Worsnop, D. R. and Wahner, A. and Wildt, J. and Mentel, Th. F. and Petaja, T and Lonn, G and Schobesberger, S. and Dal Maso, M. and Trimborn, A. and Kulmala, M. and Worsnop, D. R. and Wahner, A. and Wildt, J. and Mentel, Th. F.},
 journal = {Atmospheric Chemistry and Physics},
 number = {11}
}
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