分子束中含氮类星际分子及其团簇的同步辐射光电离研究

在已发现的近200种星际分子中，含氮类有机分子被认为是与生命起源最密切相关的分子。分子束中，这些分子之间以及与水和甲醇等溶剂分子可形成各种分子团簇。研究这些分子团簇在真空紫外光诱导下的离子-分子反应已成为当前实验室条件下研究星际化学的重要途径。本项目中，拟应用合肥同步辐射实验室可调谐的同步辐射光和相关设备，对超音速膨胀分子束中的含氮类星际分子单体及其团簇进行单光子电离，并应用飞行时间质谱仪探测，通过采集各个碎片离子的光电离效率谱(PIE)，获得其电离能、离子出现势、电离截面等物化参数。结合理论计算(从头算和密度泛函)，重点研究光电离后发生的团簇内离子-分子反应过程（如质子转移和碳－碳/氮键断裂等），获得它们的反应动力学信息(如解离通道、过渡态、解离产物等)，为人们构建完整的星际分子化学反应网络体系提供重要依据。本项目拟将甲胺、乙腈、氨基乙腈、乙酰胺分子及其混合团簇作为研究的模型体系。

There are nearly 200 molecules were identified in interstellar medium (ISM). Among them, N-containing ISM molecules were considered as the important prebiotic molecules, which were thought to be involved in the process leading to the origin of life. Study on the ion-molecule reaction occurred inside of the cluster of these N-containing molecules under outer space-like environment in the laboratory has been a hot topic. In present proposal, we plan to detect and study ion-molecule reaction within their clusters and its hydrated clusters in the gas phase by employing synchrotron VUV single photon ionization method. Combining measurement of the cation and fragments' PIE with ab initio/DFT calculations, we expect to obtain some important physical chemistry parameters such as ionization energies (IE), appearance energies (AE), enthalpy etc. The present study would help us to understand their photoionization and photo fragmentation processes (dissociation channel, tranistion state, products) and thereafter ion-molecule reaction processes (including proton transfer and C-C/N cleavage etc). The objects in present project would be the typical N-containing intersteller molecules including acetonitrile, methylamine, aminoacetonitrile, acetamide and their mixed clusters in the gas phase.