激光电离飞行时间质谱法研究Al原子与卤代甲烷气相化学反应

Laser Photoionization TOF-MS Studies on Chemical Reactions of Laser Ablated Al Atom with Halomethanes

利用分子束和飞行时间质谱技术研究了激光烧蚀金属Ａｌ原子与４种不同的卤代甲烷：ＣＣｌ４、ＣＦ３Ｃｌ。ＣＦ３Ｂｒ、ＣＦ４的气相反应。由激光电离飞行时间质谱检测的结果表明，Ａｌ与ＣＦ３Ｃｌ反应生成ＡｌＣｌ，而与ＣＦ３Ｂｒ反应生成ＡｌＢｒ，与ＣＣｌ４及ＣＦ４反应分别生成ＡｌＣｌ及ＡｌＦ。可以认为此类反应是一步完成的，反应势垒的主要来源是活性原子与中心Ｃ原子的Ｃｏｕｌｏｍｂ引力。

The gas-phase reactions between laser ablated Al atom and four different kinds of halomethane(CCl_4,CF_3Cl,CF_3Br,CF_4)are studied by laser photoionization time-of-flight mass spectrometer(TOF-MS)coupled with a pulse molecular beam device.The TOF mass spectra of neutral products show that AlCl or AlBr is produced more easily than AlF in the reaction of Al atom with CF_3Cl or CF_3Br,while AlF or AlCl is produced in the Al atom with CF_4 or CCl_4 reaction.Our results suggest that a Coulomb barrier in the exit channel has a governing role in the reactivity of aluminum with the halomethanes.