Abstract
AbstractCO2-rich planetary atmospheres are continuously exposed to ionising radiation driving major photochemical processes. In the Martian atmosphere, CO2 clusters are predicted to exist at high altitudes motivating a deeper understanding of their photochemistry. In this joint experimental-theoretical study, we investigate the photoreactions of CO2 clusters (≤2 nm) induced by soft X-ray ionisation. We observe dramatically enhanced production of $${{{{{{{{\rm{O}}}}}}}}}_{2}^{+}$$
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from photoionized CO2 clusters compared to the case of the isolated molecule and identify two relevant reactions. Using quantum chemistry calculations and multi-coincidence mass spectrometry, we pinpoint the origin of this enhancement: A size-dependent structural transition of the clusters from a covalently bonded arrangement to a weakly bonded polyhedral geometry that activates an exothermic reaction producing $${{{{{{{{\rm{O}}}}}}}}}_{2}^{+}$$
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. Our results unambiguously demonstrate that the photochemistry of small clusters/particles will likely have a strong influence on the ion balance in atmospheres.
Funder
European Cooperation in Science and Technology
Vetenskapsrådet
Publisher
Springer Science and Business Media LLC
Subject
Materials Chemistry,Biochemistry,Environmental Chemistry,General Chemistry
Cited by
2 articles.
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