H_(2)S第一吸收带振动激发态光解动力学的理论研究

Theoretical Study on Photodissociation Dynamics of Vibrational Excited States of H_(2)S in the First Absorption Band

本文利用切比雪夫实波包法研究了不同初始振动态下H_(2)S第一吸收带的光解量子动力学。由于初始振动态的波函数不同,计算得到的吸收光谱以及产物的振动态分布表现出不同的动力学特性,由于角坐标波函数的变化,初始伸缩振动激发态(1,0,0)和(0,0,1)的吸收光谱宽度和峰值与振动基态不同,而(0,1,0)振动态的吸收光谱中有两个几乎同样高的峰值.(0,1,0)态的产物振动态分布对激发能量的依赖不强,并由V=0的产物主导,但在(1,0,0)和(0,0,1)振动态的较低能量处占主导的产物是SH(X,V=1)碎片,产物的转动态分布对总能量的依讨赖性较弱,且分布非常冷并在j=1处达到峰值,但(0,1,0)振动态的转动态分布表现出明显的振荡,其各向异性参数随转动量子数的振荡行为不同于其他三种振动态的各向异性参数.

The photodissociation quantum dynamics for the first absorption band of H_(2)S in different initial vibrational states have been investigated using Chebyshev real wave packet method.Because of the difference of the wave functions for the initial vibrational states,the calculated absorption spectra and the distributions of vibrational and rotational state of the products display different dynamic characteristics.The width and peak position of the absorption spectra for initial stretching excited states(1,0,0)and(0,0,1)are different from that of the vibrational ground state,while the(0,1,0)vibrational state has two almost equally high peaks in its absorption spectrum because of the change of wave function in angular coordinate.The product vibrational state distribution for(0,1,0)initial state weakly depends on the excitation energy and is dominated by the products of v=0,but SH(v=1)fragment is dominant at lower energy for(1,0,0)and(0,0,1)vibrational states.The rotational state distributions of products are very cold with the peak at j=1 for these four states and weakly depend on the total energy.Besides,the rotational state distribution from(0,1,0)vibrational state displays strong oscillation,and its anisotropic parameter with rotational quantum numbers is also different from that of the other three vibrational states.