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Ultrafast Dynamics Through Conical Intersections in 2,6-dimethylpyridine Studied with Time-resolved Photoelectron Imaging
Xue-jun Qiu1,2, Rong-shu Zhu3, Yan-qi Xu1,2, Abulimiti Bumaliya1,2, Song Zhang1,2, Bing Zhang1,2
1.State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Instituteof Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China;2.Graduate School of the Chinese Academy of Sciences, Beijing 100049, China;3.Environmental Science and Engineering Research Center, Harbin Institute of Technology Shenzhen Graduate School, Shenzhen 518055, China
Abstract:
The ultrafast dynamics through conical intersections in 2,6-dimethylpyridine has been stud-ied by femtosecond time-resolved photoelectron imaging coupled with time-resolved mass spectroscopy. Upon absorption of 266 nm pump laser, 2,6-dimethylpyridine is excited to the S2 state with a ππ* character from S0state. The time evolution of the parent ion sig-nals consists of two exponential decays. One is a fast component on a timescale of 635 fs and the other is a slow component with a timescale of 4.37 ps. Time-dependent photo-electron angular distributions and energy-resolved photoelectron spectroscopy are extracted from time-resolved photoelectron imaging and provide the evolutive information of S2 state. In brief, the ultrafast component is a population transfer from S2 to S1 through the S2/S1 conical intersections, the slow component is attributed to simultaneous IC from the S2 state and the higher vibrational levels of S1 state to S0 state, which involves the coupling of S2/S0 and S1/S0 conical intersections. Additionally, the observed ultrafast S2→S1 transition occurs only with an 18% branching ratio.
Key words:  2,6-dimethylpyridine, Photoelectron imaging, Conical intersection, Internal conversion, Time-resolved spectroscopy
FundProject:
利用时间分辨的光电子影像技术研究2,6-二甲基吡啶分子锥形交叉超快动力学
邱学军1,2, 朱荣淑3, 徐晏琪1,2, 布玛利亚·阿布力米提1,2, 张嵩1,2, 张冰*1,2
1.中国科学院武汉物理与数学研究所,波谱与原子分子物理国家重点实验室,武汉430071;2.中国科学院研究生院,北京 100049;3.哈尔滨工业大学深圳研究生院环境科学与工程研究中心,深圳518055)
摘要:
利用时间分辨的飞秒光电子影像技术结合时间分辨的质谱技术,研究了2,6-二甲基吡啶分子锥形交叉超快动力学过程. 2,6-二甲基吡啶分子吸收266 nm泵浦光从基态跃迁至S2态(π-π*). 母体离子时间变化曲线包含两个指数函数,一个是时间常数为635 fs的快速组分,另一个是时间常数为4.37 ps的慢速组分. 通过时间分辨光电子影像得到的时间依赖的光电子角度分布和能量分辨的光电子谱分布提供了S2态演变的动力学信息. 简言之,快速组分反映了通
关键词:  2,6-二甲基吡啶,光电子影像,锥形交叉,内转换,时间分辨光谱
DOI:10.1088/1674-0068/24/05/551-556
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