Paardekooper D M, Bossa J-B, Isokoski K, Linnartz H
Raymond and Beverly Sackler Laboratory for Astrophysics, Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands.
Rev Sci Instrum. 2014 Oct;85(10):104501. doi: 10.1063/1.4896754.
A new ultra-high vacuum experiment is described that allows studying photo-induced chemical processes in interstellar ice analogues. MATRI(2)CES - a Mass Analytical Tool to study Reactions in Interstellar ICES applies a new concept by combining laser desorption and time-of-flight mass spectrometry with the ultimate goal to characterize in situ and in real time the solid state evolution of organic compounds upon UV photolysis for astronomically relevant ice mixtures and temperatures. The performance of the experimental setup is demonstrated by the kinetic analysis of the different photoproducts of pure methane (CH4) ice at 20 K. A quantitative approach provides formation yields of several new species with up to four carbon atoms. Convincing evidence is found for the formation of even larger species. Typical mass resolutions obtained range from M/ΔM ∼320 to ∼400 for CH4 and argon, respectively. Additional tests show that the typical detection limit (in monolayers) is ⩽0.02 ML, substantially more sensitive than the regular techniques used to investigate chemical processes in interstellar ices.
本文描述了一种新型的超高真空实验，该实验能够研究星际冰类似物中的光致化学过程。MATRI(2)CES——一种用于研究星际冰中反应的质量分析工具，通过将激光解吸和飞行时间质谱相结合，应用了一种新概念，其最终目标是原位实时表征与天文学相关的冰混合物在紫外光解作用下有机化合物在固态下的演化情况，以及不同温度下的变化。通过对20K时纯甲烷（CH4）冰的不同光产物进行动力学分析，证明了该实验装置的性能。一种定量方法提供了几种含多达四个碳原子的新物种的生成产率。还发现了形成更大物种的确凿证据。对于CH4和氩气，典型的质量分辨率分别为M/ΔM ∼320至∼400。额外的测试表明，典型的检测限（以单层计）⩽0.02 ML，比用于研究星际冰中化学过程的常规技术灵敏得多。
