Schrauwen Johanna G M, Cuppen Herma M, Ioppolo Sergio, Redlich Britta
HFML-FELIX Laboratory, IMM, Radboud University, 6525 ED Nijmegen, The Netherlands.
Institute of Molecules and Materials (IMM), Radboud University, 6525 AJ Nijmegen, The Netherlands.
J Phys Chem A. 2025 Jul 31;129(30):6883-6895. doi: 10.1021/acs.jpca.5c03186. Epub 2025 Jul 18.
Methane in the solid state is often studied in interaction with water, either as clathrate hydrates or as interstellar ice in a water-rich ice environment. Using free-electron laser infrared irradiation, we studied the interaction between CH and HO through energy dissipation after on-resonance vibrational excitation. The observed changes in the ice structure are largely independent of the vibrational mode excited and suggest an energy-dissipation-induced local heating of the ice. Local heating results in desorption for the two pure crystalline phases of CH, a phase transition to phase II for metastable CH and a 1:10 HO:CH mixture, and segregation for the 1:1 and 1:5 HO:CH ice mixtures. Local heating only occurs when the infrared irradiation is on resonance with a vibrational mode of the system in the case of the pure CH ices, suggesting that a sufficient absorption cross section is required to convert the on-resonance vibrational energy into general heating.
固态甲烷通常在与水相互作用的情况下被研究，其形式可以是笼形水合物，也可以是富含水的冰环境中的星际冰。我们使用自由电子激光红外辐射，通过共振振动激发后的能量耗散研究了CH与HO之间的相互作用。观察到的冰结构变化在很大程度上与激发的振动模式无关，这表明能量耗散导致了冰的局部加热。局部加热导致CH的两种纯晶相发生解吸，亚稳态CH和1:10 HO:CH混合物转变为II相，以及1:1和1:5 HO:CH冰混合物发生分离。在纯CH冰的情况下，只有当红外辐射与系统的振动模式共振时才会发生局部加热，这表明需要足够的吸收截面才能将共振振动能量转化为一般加热。
