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\n\n \n \n \n \n \n \n Mid-IR and VUV spectroscopic characterisation of thermally processed and electron irradiated CO2 astrophysical ice analogues.\n \n \n \n \n\n\n \n Mifsud, D.; Kaňuchová, Z.; Ioppolo, S.; Herczku, P.; Traspas Muiña, A.; Field, T.; Hailey, P.; Juhász, Z.; Kovács, S.; Mason, N.; McCullough, R.; Pavithraa, S.; Rahul, K.; Paripás, B.; Sulik, B.; Chou, S.; Lo, J.; Das, A.; Cheng, B.; Rajasekhar, B.; Bhardwaj, A.; and Sivaraman, B.\n\n\n \n\n\n\n
Journal of Molecular Spectroscopy, 385: 111599. March 2022.\n
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\n\n \n \n ![\"Mid-IR](\"//bibbase.org/img/filetypes/link.svg\"\n\t "\\"Paper\\"\n\t")
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@article{mifsud_mid-ir_2022,\n\ttitle = {Mid-{IR} and {VUV} spectroscopic characterisation of thermally processed and electron irradiated {CO2} astrophysical ice analogues},\n\tvolume = {385},\n\tissn = {00222852},\n\turl = {https://linkinghub.elsevier.com/retrieve/pii/S002228522200025X},\n\tdoi = {10.1016/j.jms.2022.111599},\n\tlanguage = {en},\n\turldate = {2023-06-26},\n\tjournal = {Journal of Molecular Spectroscopy},\n\tauthor = {Mifsud, D.V. and Kaňuchová, Z. and Ioppolo, S. and Herczku, P. and Traspas Muiña, A. and Field, T.A. and Hailey, P.A. and Juhász, Z. and Kovács, S.T.S. and Mason, N.J. and McCullough, R.W. and Pavithraa, S. and Rahul, K.K. and Paripás, B. and Sulik, B. and Chou, S.-L. and Lo, J.-I. and Das, A. and Cheng, B.-M. and Rajasekhar, B.N. and Bhardwaj, A. and Sivaraman, B.},\n\tmonth = mar,\n\tyear = {2022},\n\tpages = {111599},\n}\n\n\n
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\n\n \n \n \n \n \n \n Ozone production in electron irradiated CO2:O2 ices.\n \n \n \n \n\n\n \n Mifsud, D. V.; Kaňuchová, Z.; Ioppolo, S.; Herczku, P.; Muiña, A. T.; Sulik, B.; Rahul, K. K.; Kovács, S. T. S.; Hailey, P. A.; McCullough, R. W.; Mason, N. J.; and Juhász, Z.\n\n\n \n\n\n\n
Physical Chemistry Chemical Physics, 24(30): 18169–18178. August 2022.\n
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@article{mifsud_ozone_2022,\n\ttitle = {Ozone production in electron irradiated {CO2}:{O2} ices},\n\tvolume = {24},\n\tissn = {1463-9084},\n\tshorttitle = {Ozone production in electron irradiated {CO2}},\n\turl = {https://pubs.rsc.org/en/content/articlelanding/2022/cp/d2cp01535h},\n\tdoi = {10.1039/D2CP01535H},\n\tabstract = {The detection of ozone (O3) in the surface ices of Ganymede, Jupiter's largest moon, and of the Saturnian moons Rhea and Dione, has motivated several studies on the route of formation of this species. Previous studies have successfully quantified trends in the production of O3 as a result of the irradiation of pure molecular ices using ultraviolet photons and charged particles (i.e., ions and electrons), such as the abundances of O3 formed after irradiation at different temperatures or using different charged particles. In this study, we extend such results by quantifying the abundance of O3 as a result of the 1 keV electron irradiation of a series of 14 stoichiometrically distinct CO2:O2 astrophysical ice analogues at 20 K. By using mid-infrared spectroscopy as our primary analytical tool, we have also been able to perform a spectral analysis of the asymmetric stretching mode of solid O3 and the variation in its observed shape and profile among the investigated ice mixtures. Our results are important in the context of better understanding the surface composition and chemistry of icy outer Solar System objects, and may thus be of use to future interplanetary space missions such as the ESA Jupiter Icy Moons Explorer and the NASA Europa Clipper missions, as well as the recently launched NASA James Webb Space Telescope.},\n\tlanguage = {en},\n\tnumber = {30},\n\turldate = {2023-06-26},\n\tjournal = {Physical Chemistry Chemical Physics},\n\tauthor = {Mifsud, Duncan V. and Kaňuchová, Zuzana and Ioppolo, Sergio and Herczku, Péter and Muiña, Alejandra Traspas and Sulik, Béla and Rahul, K. K. and Kovács, Sándor T. S. and Hailey, Perry A. and McCullough, Robert W. and Mason, Nigel J. and Juhász, Zoltán},\n\tmonth = aug,\n\tyear = {2022},\n\tpages = {18169--18178},\n}\n\n\n
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\n The detection of ozone (O3) in the surface ices of Ganymede, Jupiter's largest moon, and of the Saturnian moons Rhea and Dione, has motivated several studies on the route of formation of this species. Previous studies have successfully quantified trends in the production of O3 as a result of the irradiation of pure molecular ices using ultraviolet photons and charged particles (i.e., ions and electrons), such as the abundances of O3 formed after irradiation at different temperatures or using different charged particles. In this study, we extend such results by quantifying the abundance of O3 as a result of the 1 keV electron irradiation of a series of 14 stoichiometrically distinct CO2:O2 astrophysical ice analogues at 20 K. By using mid-infrared spectroscopy as our primary analytical tool, we have also been able to perform a spectral analysis of the asymmetric stretching mode of solid O3 and the variation in its observed shape and profile among the investigated ice mixtures. Our results are important in the context of better understanding the surface composition and chemistry of icy outer Solar System objects, and may thus be of use to future interplanetary space missions such as the ESA Jupiter Icy Moons Explorer and the NASA Europa Clipper missions, as well as the recently launched NASA James Webb Space Telescope.\n
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\n\n \n \n \n \n \n \n Comparative electron irradiations of amorphous and crystalline astrophysical ice analogues.\n \n \n \n \n\n\n \n Mifsud, D. V.; Hailey, P. A.; Herczku, P.; Sulik, B.; Juhász, Z.; Kovács, S. T. S.; Kaňuchová, Z.; Ioppolo, S.; McCullough, R. W.; Paripás, B.; and Mason, N. J.\n\n\n \n\n\n\n
Physical Chemistry Chemical Physics, 24(18): 10974–10984. May 2022.\n
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@article{mifsud_comparative_2022,\n\ttitle = {Comparative electron irradiations of amorphous and crystalline astrophysical ice analogues},\n\tvolume = {24},\n\tissn = {1463-9084},\n\turl = {https://pubs.rsc.org/en/content/articlelanding/2022/cp/d2cp00886f},\n\tdoi = {10.1039/D2CP00886F},\n\tabstract = {Laboratory studies of the radiation chemistry occurring in astrophysical ices have demonstrated the dependence of this chemistry on a number of experimental parameters. One experimental parameter which has received significantly less attention is that of the phase of the solid ice under investigation. In this present study, we have performed systematic 2 keV electron irradiations of the amorphous and crystalline phases of pure CH3OH and N2O astrophysical ice analogues. Radiation-induced decay of these ices and the concomitant formation of products were monitored in situ using FT-IR spectroscopy. A direct comparison between the irradiated amorphous and crystalline CH3OH ices revealed a more rapid decay of the former compared to the latter. Interestingly, a significantly lesser difference was observed when comparing the decay rates of the amorphous and crystalline N2O ices. These observations have been rationalised in terms of the strength and extent of the intermolecular forces present in each ice. The strong and extensive hydrogen-bonding network that exists in crystalline CH3OH (but not in the amorphous phase) is suggested to significantly stabilise this phase against radiation-induced decay. Conversely, although alignment of the dipole moment of N2O is anticipated to be more extensive in the crystalline structure, its weak attractive potential does not significantly stabilise the crystalline phase against radiation-induced decay, hence explaining the smaller difference in decay rates between the amorphous and crystalline phases of N2O compared to those of CH3OH. Our results are relevant to the astrochemistry of interstellar ices and icy Solar System objects, which may experience phase changes due to thermally-induced crystallisation or space radiation-induced amorphisation.},\n\tlanguage = {en},\n\tnumber = {18},\n\turldate = {2023-06-26},\n\tjournal = {Physical Chemistry Chemical Physics},\n\tauthor = {Mifsud, Duncan V. and Hailey, Perry A. and Herczku, Péter and Sulik, Béla and Juhász, Zoltán and Kovács, Sándor T. S. and Kaňuchová, Zuzana and Ioppolo, Sergio and McCullough, Robert W. and Paripás, Béla and Mason, Nigel J.},\n\tmonth = may,\n\tyear = {2022},\n\tpages = {10974--10984},\n}\n\n\n
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\n Laboratory studies of the radiation chemistry occurring in astrophysical ices have demonstrated the dependence of this chemistry on a number of experimental parameters. One experimental parameter which has received significantly less attention is that of the phase of the solid ice under investigation. In this present study, we have performed systematic 2 keV electron irradiations of the amorphous and crystalline phases of pure CH3OH and N2O astrophysical ice analogues. Radiation-induced decay of these ices and the concomitant formation of products were monitored in situ using FT-IR spectroscopy. A direct comparison between the irradiated amorphous and crystalline CH3OH ices revealed a more rapid decay of the former compared to the latter. Interestingly, a significantly lesser difference was observed when comparing the decay rates of the amorphous and crystalline N2O ices. These observations have been rationalised in terms of the strength and extent of the intermolecular forces present in each ice. The strong and extensive hydrogen-bonding network that exists in crystalline CH3OH (but not in the amorphous phase) is suggested to significantly stabilise this phase against radiation-induced decay. Conversely, although alignment of the dipole moment of N2O is anticipated to be more extensive in the crystalline structure, its weak attractive potential does not significantly stabilise the crystalline phase against radiation-induced decay, hence explaining the smaller difference in decay rates between the amorphous and crystalline phases of N2O compared to those of CH3OH. Our results are relevant to the astrochemistry of interstellar ices and icy Solar System objects, which may experience phase changes due to thermally-induced crystallisation or space radiation-induced amorphisation.\n
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\n\n \n \n \n \n \n \n Sulfur Ion Implantations Into Condensed CO $_{\\textrm{2}}$ : Implications for Europa.\n \n \n \n \n\n\n \n Mifsud, D. V.; Kaňuchová, Z.; Herczku, P.; Juhász, Z.; Kovács, S. T. S.; Lakatos, G.; Rahul, K. K.; Rácz, R.; Sulik, B.; Biri, S.; Rajta, I.; Vajda, I.; Ioppolo, S.; McCullough, R. W.; and Mason, N. J.\n\n\n \n\n\n\n
Geophysical Research Letters, 49(24). December 2022.\n
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@article{mifsud_sulfur_2022,\n\ttitle = {Sulfur {Ion} {Implantations} {Into} {Condensed} {CO} $_{\\textrm{2}}$ : {Implications} for {Europa}},\n\tvolume = {49},\n\tissn = {0094-8276, 1944-8007},\n\tshorttitle = {Sulfur {Ion} {Implantations} {Into} {Condensed} {CO} $_{\\textrm{2}}$},\n\turl = {https://onlinelibrary.wiley.com/doi/10.1029/2022GL100698},\n\tdoi = {10.1029/2022GL100698},\n\tlanguage = {en},\n\tnumber = {24},\n\turldate = {2023-02-25},\n\tjournal = {Geophysical Research Letters},\n\tauthor = {Mifsud, D. V. and Kaňuchová, Z. and Herczku, P. and Juhász, Z. and Kovács, S. T. S. and Lakatos, G. and Rahul, K. K. and Rácz, R. and Sulik, B. and Biri, S. and Rajta, I. and Vajda, I. and Ioppolo, S. and McCullough, R. W. and Mason, N. J.},\n\tmonth = dec,\n\tyear = {2022},\n}\n\n\n
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\n\n \n \n \n \n \n \n Energetic electron irradiations of amorphous and crystalline sulphur-bearing astrochemical ices.\n \n \n \n \n\n\n \n Mifsud, D. V.; Herczku, P.; Rácz, R.; Rahul, K. K.; Kovács, S. T. S.; Juhász, Z.; Sulik, B.; Biri, S.; McCullough, R. W.; Kaňuchová, Z.; Ioppolo, S.; Hailey, P. A.; and Mason, N. J.\n\n\n \n\n\n\n
Frontiers in Chemistry, 10. 2022.\n
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\n\n \n \n Paper\n \n \n\n \n\n \n link\n \n \n\n bibtex\n \n\n \n \n \n abstract \n \n\n \n\n \n \n \n \n \n \n \n\n \n \n \n\n\n\n
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@article{mifsud_energetic_2022,\n\ttitle = {Energetic electron irradiations of amorphous and crystalline sulphur-bearing astrochemical ices},\n\tvolume = {10},\n\tissn = {2296-2646},\n\turl = {https://www.frontiersin.org/articles/10.3389/fchem.2022.1003163},\n\tabstract = {Laboratory experiments have confirmed that the radiolytic decay rate of astrochemical ice analogues is dependent upon the solid phase of the target ice, with some crystalline molecular ices being more radio-resistant than their amorphous counterparts. The degree of radio-resistance exhibited by crystalline ice phases is dependent upon the nature, strength, and extent of the intermolecular interactions that characterise their solid structure. For example, it has been shown that crystalline CH3OH decays at a significantly slower rate when irradiated by 2 keV electrons at 20 K than does the amorphous phase due to the stabilising effect imparted by the presence of an extensive array of strong hydrogen bonds. These results have important consequences for the astrochemistry of interstellar ices and outer Solar System bodies, as they imply that the chemical products arising from the irradiation of amorphous ices (which may include prebiotic molecules relevant to biology) should be more abundant than those arising from similar irradiations of crystalline phases. In this present study, we have extended our work on this subject by performing comparative energetic electron irradiations of the amorphous and crystalline phases of the sulphur-bearing molecules H2S and SO2 at 20 K. We have found evidence for phase-dependent chemistry in both these species, with the radiation-induced exponential decay of amorphous H2S being more rapid than that of the crystalline phase, similar to the effect that has been previously observed for CH3OH. For SO2, two fluence regimes are apparent: a low-fluence regime in which the crystalline ice exhibits a rapid exponential decay while the amorphous ice possibly resists decay, and a high-fluence regime in which both phases undergo slow exponential-like decays. We have discussed our results in the contexts of interstellar and Solar System ice astrochemistry and the formation of sulphur allotropes and residues in these settings.},\n\turldate = {2023-02-25},\n\tjournal = {Frontiers in Chemistry},\n\tauthor = {Mifsud, Duncan V. and Herczku, Péter and Rácz, Richárd and Rahul, K. K. and Kovács, Sándor T. S. and Juhász, Zoltán and Sulik, Béla and Biri, Sándor and McCullough, Robert W. and Kaňuchová, Zuzana and Ioppolo, Sergio and Hailey, Perry A. and Mason, Nigel J.},\n\tyear = {2022},\n}\n\n\n
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\n Laboratory experiments have confirmed that the radiolytic decay rate of astrochemical ice analogues is dependent upon the solid phase of the target ice, with some crystalline molecular ices being more radio-resistant than their amorphous counterparts. The degree of radio-resistance exhibited by crystalline ice phases is dependent upon the nature, strength, and extent of the intermolecular interactions that characterise their solid structure. For example, it has been shown that crystalline CH3OH decays at a significantly slower rate when irradiated by 2 keV electrons at 20 K than does the amorphous phase due to the stabilising effect imparted by the presence of an extensive array of strong hydrogen bonds. These results have important consequences for the astrochemistry of interstellar ices and outer Solar System bodies, as they imply that the chemical products arising from the irradiation of amorphous ices (which may include prebiotic molecules relevant to biology) should be more abundant than those arising from similar irradiations of crystalline phases. In this present study, we have extended our work on this subject by performing comparative energetic electron irradiations of the amorphous and crystalline phases of the sulphur-bearing molecules H2S and SO2 at 20 K. We have found evidence for phase-dependent chemistry in both these species, with the radiation-induced exponential decay of amorphous H2S being more rapid than that of the crystalline phase, similar to the effect that has been previously observed for CH3OH. For SO2, two fluence regimes are apparent: a low-fluence regime in which the crystalline ice exhibits a rapid exponential decay while the amorphous ice possibly resists decay, and a high-fluence regime in which both phases undergo slow exponential-like decays. We have discussed our results in the contexts of interstellar and Solar System ice astrochemistry and the formation of sulphur allotropes and residues in these settings.\n
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