吡啶团簇的飞秒光电离和从头计算研究

The Femtosecond Laser Photoionization and ab initio Calculation Studies of Pyridine Clusters

用飞秒激光电离飞行时间质谱研究了吡啶分子团簇在 4 0 0nm波长下的多光子光电离 ,实验观测到一系列的质子化和非质子化团簇离子 .结果表明 ,质子转移也能发生在弱氢键结合的分子间 .通过分析离子峰宽和离子信号强度随气源压力的变化 ,得到质子化团簇离子来源于大团簇离子的碎裂 ,而非质子化团簇离子是中性团簇直接电离的结果 .从头计算结果表明 ,吡啶团簇是通过弱氢键C -H…N结合在一起的 。

The multiphoton ionization of pyridine clusters was studied by use of 400 nm femtosecond laser and TOF MS. A series of protonated and unprotonated pyridine cluster ions were detected, which indicates that the proton transfer can also occur in weak hydrogen bonded clusters. The analysis of both ion peak width and the ion intensity's change with the gas resource pressure suggests that the protonated cluster ions are coming from the fragment of larger cluster ions and the relevant unprotonated cluster ions are the direct ionization products of neutral clusters. ab initio calculation results indicate the pyridine clusters are formed by weak hydrogen bonds C - H...N and the dissociation of cluster ions prefers to produce protonated products.