C4H5N-(NH3)n氢键团簇的多光子电力与从头计算

在３５５和５３２ｎｍ激光波长下用ＴＯＦ质谱仪研究了Ｃ４Ｈ５Ｎ－（ＮＨ３）ｎ系列氢键团簇体系的多光子电离，实验发现，两波长下除了得到一系列团簇离子Ｃ４Ｈ５Ｎ－（ＮＨ３）ｎ＾＋外，还观测到一系列质子化产物Ｃ４Ｈ５Ｎ－（ＮＨ３）ｎ－Ｈ＾＋，这些质子化产物来自于光电离过程中团簇内部的质子转移反应；Ｃ４Ｈ５Ｎ－（ＮＨ３）ｎ＾＋系列离子出现反常强度变化，即Ｃ４Ｈ５Ｎ－（ＮＨ３）２＾＋离子强度较Ｃ４Ｈ５Ｎ－（Ｎ

Multiphoton lonization and Ab Initio Calculation of C4H5N - (NH3)n Hydrogen-bond Clusters

Multiphoton ionization of binary clusters (C4H5N)－ NH3 at 355 and 532 nm have been investigated using a TOF mass spectrometer. The experimenal results showed that normal cluster ions and protonated cluster ions were produced at both laser wavelengths. The protonated products came from the intracluster proton transfer reaction. The existence of NH3 in the clusters increased the ionization cross sections of the clusters. The higher ionization efficiency at 355 nm results from the (2＋ 1) resonance multiphoton ionization of the pyrrole molecule. A peculiar low abundance of was observed, ab initio calculations indicated that when ammonia number n ≥ 3,two hydrogen bonds between ammnia chain and pyrrole ring can be formed, and the cluster become more stable. The channel ratio for the formation of protonated and unprotonated products increases with the increase of n,in agreement with the trend of proton affinity of (C4H5N)－ (NH3 )n.