Bossa J-B, Paardekooper D M, Isokoski K, Linnartz H
Raymond and Beverly Sackler Laboratory for Astrophysics, Leiden Observatory, Leiden University, P.O. Box 9513, NL 2300 RA Leiden, The Netherlands.
Phys Chem Chem Phys. 2015 Jul 14;17(26):17346-54. doi: 10.1039/c5cp00578g.
The ice photochemistry of pure methane (CH4) is studied at 20 K upon VUV irradiation from a microwave discharge H2 flow lamp. Laser Desorption Post-Ionization Time-Of-Flight Mass Spectrometry (LDPI TOF-MS) is used for the first time to determine branching ratios of primary reactions leading to CH3, CH2, and CH radicals, typically for fluences as expected in space. This study is based on a stable end-products analysis and the mass spectra are interpreted using an appropriate set of coupled reactions and rate constants. This yields clearly different values from previous gas phase studies. The matrix environment as well as the higher efficiency of reverse reactions in the ice clearly favor CH3 radical formation as the main first generation photoproduct.
在20K温度下，利用微波放电氢气流灯发出的真空紫外光辐照，对纯甲烷（CH₄）的冰光化学进行了研究。首次使用激光解吸后电离飞行时间质谱（LDPI TOF-MS）来确定导致CH₃、CH₂和CH自由基的初级反应的分支比，这些反应通常在太空中预期的通量下发生。本研究基于稳定终产物分析，并使用一组适当的耦合反应和速率常数对质谱进行解释。这产生了与先前气相研究明显不同的值。冰中的基质环境以及逆反应的更高效率明显有利于CH₃自由基作为主要第一代光产物的形成。
