CS_2分子~1B_2(~1Σ_u^+)态预解离动力学研究  

Photodissociation Dynamics of CS_2 at the ~1B_2(~1Σ_u^+) State

作　　者：郭颖[1] 徐海峰[1] 李奇峰[1] 石勇[1] 戴静华[1] 刘世林[1] 马兴孝[1] 

机构地区：[1]中国科学院选键化学实验室

出　　处：《Chinese Journal of Chemical Physics》2005年第2期145-151,共7页化学物理学报（英文）

基　　金：ProjectsupportedbytheNationalNaturalScienceFoundationofChina(20273063)andtheStateKeyDevelopmentProgramforBasicResearchofChina(1999075304)

摘　　要：研究了CS2 分子1B2 (1Σ+u )预离解态线形势垒下的g振动能级光解动力学,包括预解离寿命、产物振转布居、平动振动转动能量分配和解离通道分支比.在实验过程中,一束可调谐激光激发超声射流冷却的CS2 分子到1B2 (1Σ+u )电子态,光解产物CS用另一束可调谐激光通过激光诱导荧光(LIF)方法检测.通过拟合光解碎片激发谱的谱峰轮廓,获得了源于不同跃迁初始态的1B2 (1Σ+u )态g振动能级的预解离寿命.通过分析CS的LIF光谱,则获得了不同光解波长下CS碎片的v=0~8振动态布居、v=1、4 ~8振动态的转动布居、能量分配以及两个预解离通道CS(X1Σ+ ) +S(3PJ)和CS(X1Σ+ ) +S(1D2 )的分支比.实验还考察了初始态弯曲振动量子数v2″、振动角动量量子数l对解离动力学的影响.发现v2″的影响不大,而l的影响却是明显的.较大的l(=K)对应于较短的寿命和较小的通道分支比S(3PJ) /S(1D2 ),即大的l(=K)有利于预解离的发生,同时更有利于产生S(1D2 ).The predissociation dynamics of CS_2 at the g vibrational level of the ~1B_2(~1Σ^+_u) state has been studied, by measuring the predissociation lifetimes from the photofragment CS excitation (PHOFEX) spectrum and the ro-vibrational populations of CS fragment from the laser-induced fluorescence(LIF) spectrum. It is found that the angular momentum quantum number K of the g level accelerates the dissociation speed of CS_2 at the ~1B_2(~1Σ^+_u) state, and increases the branching ratio of S(~1D_2)/S(~3P_J) for the two dissociation channels, CS(X ~1Σ^+)+S(~1D_2) and CS(X ~1Σ^+)+S(~3P_J). The dissociation mechanism was discussed based upon the observations.

关 键 词：CS2分子^1B2(^1∑u^+)态 预解离寿命 通道分支比 振转能量分配 光解动力学 

分 类 号：O643.1[理学—物理化学]