邻二氯苯激发态动力学.pdf

物理化学学报( Wuli Huaxue Xuebao)
September
Acta Phys. -Chim. Sin. 2015, 37(9), 1655-1661
1655
Article
doi:10.3866/PKU. WHXB20150629
www.whxb.pku.edu.cn
邻二氯苯激发态动力学
李晓营王利王艳秋。宋哲刘本康
(辽宁师范大学物理与电子学院,辽宁大连116029、大连民族大学物理与材料工程学院,辽宁大连11600
3中国科学院大连化学物理研究所,分子反应动力学国家重点实验室,辽宁大连116023)
摘要:利用飞秒分辨的激光泵浦-探测技术结合飞行时间质谱和光电子速度成像方法研究了邻二氯苯第一电
子单重激发态(S,)的超快动力学.邻二氯苯的S态振动基态寿命为(65110)ps,对应于S,振动基态向三重态
的系间官越过程.邻二氯苯S1的高振动激发9a218a2对应两个衰减通道,其中寿命为(458±12)fs的超快过程对
应于由处于振动激发的S1向高振动激发的基态(S)发生的内转换过程,而寿命为(90±10)ps过程则对应由
S态向三重态(7)的系间窜越过程,电离产生的光电子能谱中长寿命的谱峰可能与系间窜越过程有关.S,态高
振动态的旋轨耦合程度比低振动态的更强,导致系间窜越过程更快
关键词:邻二氯苯;振动激发;光电子成像:;光电子能谱
中图分类号:O644
dynamics of Excited o-dichlorobenzene
LI Xiao-yir
WANG
WANG Yan-qiu SONG Zhe
LIU Ben-kang
( School of Physics and Electronic Technology, Liaoning Normal University, Dalian 116029, Liaoning Province, P. R. China
ollege of Physics and Materials Engineering, Dalian Nationalities University, Dalian 116600, Liaoning Province, P. R. China
State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences
Dalian 116023, Liaoning Province, P. R. China)
Abstract: The dynamics of the first excited singlet electronic state(S, ) of o-dichlorobenzene was investigated
in real time by the femtosecond pump-probe method combined with time-of-flight mass spectroscopy and the
photoelectron velocity mapping technique. The lifetime of the S, vibrational ground state was determined
experimentally to be( 651 +10)ps, corresponding to the intersystem crossing process from the S, state to the
triplet state. Two decay channels were found in the S, vibrationally excited mode 9a 18a, The fast process
lifetime constant(458)s)is ecause of the internal conversion from the S vibrationally ecited mode to
the highly vibrationally excited ground state( So). The slow process(lifetime constant(90 t 10)ps)is attributed
to the intersystem crossing process from the S, state to the triplet state( Photoelectrons with long lifetime
characteristics in the spectrum might be connected with the intersystem crossing process. Enhanced spin-
orbital coupling in the S highly vibrationally excited state accelerates the intersystem crossing process
Key Words: o-dichlorobenzene Vibrational excitation; Photoelectron imaging; Photoelectron kinetic
energy spectrum
1引言
着非常重要的作用,相关动力学过程研究对深入理
多原子分子激发态在光物理和光化学领域起解相关化学反应和控制其发生过程有着重要意义
Received: April 7, 2015, Revised: June 26, 2015; Published on Web: June 29, 2015
Correspondingauthors.WANGLi,Email:liwangye(@danu.edu.cn.LIUBen-kang,Email:liubk@dicpaccn
The project was supported by the National Natural Science Foundation of China (21303199)
国家自然科学基金(21303199)资助项目
Editorial office of Acta Physico-chimica Sinica