Ganguly Smita, Barreiro-Lage Dario, Walsh Noelle, Oostenrijk Bart, Sorensen Stacey L, Díaz-Tendero Sergio, Gisselbrecht Mathieu
Department of Physics, Lund University, Box 118, SE-221 00 Lund, Sweden.
Departamento de Química - Módulo 13, Universidad Autónoma de Madrid, 28049 Madrid, Spain.
Commun Chem. 2022 Feb 4;5(1):16. doi: 10.1038/s42004-022-00629-z.
CO-rich planetary atmospheres are continuously exposed to ionising radiation driving major photochemical processes. In the Martian atmosphere, CO 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 CO clusters (≤2 nm) induced by soft X-ray ionisation. We observe dramatically enhanced production of from photoionized CO 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 . Our results unambiguously demonstrate that the photochemistry of small clusters/particles will likely have a strong influence on the ion balance in atmospheres.
富含一氧化碳的行星大气持续暴露于驱动主要光化学过程的电离辐射中。在火星大气中，预计在高海拔处存在一氧化碳团簇，这促使人们更深入地了解它们的光化学。在这项联合实验与理论研究中，我们研究了软X射线电离诱导的一氧化碳团簇（≤2纳米）的光反应。与孤立分子的情况相比，我们观察到光离子化一氧化碳团簇产生的[具体产物未明确给出]显著增强，并确定了两个相关反应。通过量子化学计算和多符合质谱分析，我们确定了这种增强的来源：团簇从共价键合排列到弱键合多面体几何结构的尺寸依赖性结构转变，这种转变激活了一个产生[具体产物未明确给出]的放热反应。我们的结果明确表明，小团簇/颗粒的光化学可能会对大气中的离子平衡产生强烈影响。
