Reaction dynamics of excited Zn atoms by off-resonant photoexcitation

研究了受激Zn原子的动力学行为。在第一阶段，研究了Zn（4^1P_1）的系间交叉和Zn（4^3P_J）与Xe的多重态内混合。研究了非共振光激发的影响。第二阶段，考察了Zn（4^1P_1）与H_2O的化学反应。研究了新生产物状态分布。金属原子和稀有气体原子之间的原子相互作用势最近已经用光谱学方法确定。研究这些系统的动力学是有益的，因为动力学数据与量子计算相结合，可以补充光谱数据来确定势。利用脉冲激光技术测定了Zn（4^1P_1）的系间交叉和Zn（4^3P_J）与Xe的多重态混合截面。在系统间穿越过程中，发现初始J态分布偏于J=2，截面在10^<-16> cm^2数量级。多重态混合的截面为10^<-18> cm^2。量子力学计算在紧密耦合处理中进行，以评估这些横截面。在假设合适的势能曲线的情况下，通过计算可以很好地再现上述实验结果。为了理解反应动力学，关于产物状态分布的信息是不可避免的。测定了Zn（4^1P_1）与H_2O反应中ZnH和OH的初旋态和振动态分布。针对H_2O对热Zn表面具有腐蚀性的特点，研制了一种结合脉冲喷嘴的流动系统。发现OH自由基在旋转和振动上都是很冷的，而ZnH自由基是热的。这些结果表明Zn（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。

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.