The interaction of methyl iodine with the surface of amorphous, cubic, and hexagonal ices has been investigated. The CH₃I desorption process has also been evaluated. We have highlighted the difference in CH₃I behavior depending on the trapping on the ice surface. The broadband UV photochemistry of CH₃I trapped at the surface of ices has been studied. Those results have been compared with UV broadband photochemistry of CH₃I bare monomer complexed with water and trapped in argon cryogenic matrices. It appears that if CH₃I interacts with water molecules or water ice by hydrogen bonding, then CH₃I does not fragment under UV irradiation. Thus, energy transfer to the network of hydrogen bonds in the ice or matrix is effective. On the other hand, to a first approximation, if CH₃I interacts by picnogen-type bonding (I⋯O), then CH₃I fragments, because the electronic relaxation seems to take place mainly at the intramolecular levels of CH₃I. Finally, we demonstrated that water ice does not catalyze the photofragmentation of CH₃I. Rather, it modifies the electronic relaxation paths, some of which lead to the fragmentation of iodomethane. This fundamental work provides an understanding of the molecular processes involved in water/ice–CH₃I interaction and the role of these molecular interactions on CH₃I photochemistry in the atmosphere.

中文翻译：

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CH3I⋯(H2O)n 配合物的光化学：从 CH3I⋯H2O 到 CH3I 与水冰的相互作用以及对大气的影响

研究了甲基碘与无定形冰、立方冰和六角冰表面的相互作用。 CH ₃ I 解吸过程也得到了评估。我们强调了 CH ₃ I 行为的差异取决于冰表面的捕获。研究了冰表面捕获的CH ₃ I的宽带紫外光化学。这些结果已与与水络合并捕获在氩低温基质中的CH ₃ I 裸单体的紫外宽带光化学进行了比较。看来如果CH ₃ I通过氢键与水分子或水冰相互作用，则CH ₃ I在紫外线照射下不会碎裂。因此，能量转移到冰或基质中的氢键网络是有效的。另一方面，对于第一近似，如果 CH ₃ I 通过 picnogen 型键合 (I⋯O) 相互作用，则 CH ₃ I 断裂，因为电子弛豫似乎主要发生在 CH ₃ I的分子内水平。最后，我们证明水冰不会催化CH ₃ I的光裂解。相反，它会改变电子弛豫路径，其中一些导致碘甲烷的裂解。这项基础工作提供了对水/冰-CH ₃ I相互作用所涉及的分子过程以及这些分子相互作用对大气中CH ₃ I光化学的作用的理解。