H_(2)S^(+)在325nm附近的光解动力学

Photodissociation Dynamics of H_(2)S^(+) near 325 nm

本文通过研究H_(2)S^(+)的光解动力学,结合时间切片离子速度成像技术和高精度的理论计算,获得了解离波长从3.25158×10^(2)nm到3.25307×10^(2)nm范围内,对应的正离子激发态为H_(2)S^(+)A_(2)A_(1)(0,13,0)K=1态的高分辨离子速度影像.基于离子速度影像获得了不同解离波长下转动态分辨的产物总平动能谱及产物角分布能谱.从实验结果中可以清楚地观察到产物转动态分布和角分布各向异性渗数随着光解波长改变.结合理论计算得到的全维势能面推测光解过程中发挥关键作用的是离子在C2v对称性下A_(2)A_(1)和B_(2)B_(2)态的非绝热耦合以及Cg对称性下在锥形交叉区域的弛豫.

We study the photodissociation dynamics of the hydrogen sulfide cations(H_(2)S^(+))using the time-sliced velocity map ion imaging(VMI)technique and high-accuracy calculations.Highresolution ion images of the S+(4S)products were measured at four photolysis wavelengths of 325.158,325.200,325.243,325.307 nm,which correspond to the excitation to the A2A1(0,13,0)K=1 state of H_(2)S^(+).Rotational stateresolved total kinetic energy releases and angular distributions have been derived as a function of the photolysis wavelengths.Notably,photolysis wavelength dependent product rotational state and anisotropy parameter distributions have been clearly observed.Full-dimensional potential energy surface characterization suggests that nonadiabatic coupling between A_(2)A_(1) and B_(2)B_(2) states at C2v configurations,as well as relaxation of the symmetry to Cs in the conical intersection region between the two states,plays a key role in the photodissociation process.