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Reaction dynamics of excited Zn atoms by off-resonant photoexcitation

非共振光激发激发锌原子的反应动力学

基本信息

批准号：
03804028
负责人：
UMEMOTO Hironobu
金额：
$ 1.22万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

项目摘要

The dynamical behavior of excited Zn atoms were examined. At the first stage, the intersystem crossing of Zn(4^1P_1) and the intramultiplet mixing of Zn(4^3P_J) by Xe were examined. Effect of the off-resonant photoexcitation was also examined. At the second stage, the chemical reactions of Zn(4^1P_1) with H_2O was examined. The nascent product state distributions were examined.The interatomic potentials between metal atoms and rare gas atoms have recently been determined by spectroscopic procedures. It is informative to study the dynamics of such systems, because dynamical data complement spectroscopic data in the determination of the potentials, when combined with quantum calculations. The cross sections for the intersystem crossing of Zn(4^1P_1) and the intramultiplet mixing of Zn(4^3P_J) by Xe were determined by using pulsed laser techniques. In the intersystem crossing processes, it was found that the initial J state distribution was skewed to J=2 and that the cross sections were in the order of 10^<-16> cm^2. The cross sections for the intramultiplet mixing were in the order of 10^<-18> cm^2. Quantum mechanical calculations were carried out within a closecoupling treatment to evaluate these cross sections. The above experimental results could well be reproduced by the calculations when suitable potential energy curves were assumed.In order to understand reaction dynamics, information on the product state distributions are inevitable. The nascent rotational and vibrational state distributions of ZnH and OH in the reaction of Zn(4^1P_1) with H_2O were determined. Since H_2O is corrosive to hot Zn surfaces, a flow system combined with a pulsed nozzle was developed. It was found that OH radicals are very cool, while ZnH radicals are hot, both rotationally and vibrationally. These results suggests that Zn(4^1P_1) abstract H from H^2O via nonlinear intermediates. The reactions with alkane hydrocarbons were also examined.

研究了激发态锌原子的动力学行为。在第一阶段，研究了锌(4^1P_1)的系间交叉和锌(4^3P_J)与Xe的多重态混合。还考察了非共振光激发的影响。在第二阶段，研究了锌(4^1P_1)与水的化学反应。研究了金属原子与稀有气体原子之间的原子间相互作用势，用光谱学方法测定了金属原子与稀有气体原子之间的原子间相互作用势。研究这类系统的动力学是有益的，因为当与量子计算相结合时，动力学数据可以补充光谱数据来确定势能。用脉冲激光技术测量了Xe原子与锌原子(4^1P_1)的系间交叉和锌原子(4^3P_J)的多重态混合截面。在系间交叉过程中，发现初始J态分布偏斜为J=2，截面为10^-lt；-16；cm^2量级，多重态内混合截面为10^-lt；-18&gt；cm^2量级。当假定合适的势能曲线时，上述实验结果可以很好地被计算重现。为了理解反应动力学，有关产物状态分布的信息是不可避免的。测定了锌(4^1P_1)与H_2O反应中锌氢化物和氢氧化锌的初始旋转态和振动态分布。针对H2O对高温锌表面具有腐蚀性的特点，研制了一种与脉冲喷嘴相结合的流动系统。研究发现，无论是转动自由基还是振动自由基，OH自由基都是很冷的，而ZnH自由基是热的。这些结果表明，锌(4^1P_1)通过非线性中间体从H^2O中提取H。还考察了与烷烃的反应。