物理化学学报 >> 2009, Vol. 25 >> Issue (04): 661-667.doi: 10.3866/PKU.WHXB200904081

研究论文 上一篇    下一篇

离子速度成像方法研究碘代正戊烷的紫外光解动力学

张延 王骏 郑秋莎 刘玉柱 张蓉蓉 胡长进 唐碧峰 张冰   

  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; 中国科学院研究生院, 北京 100049; 昆明学院物理科学与技术系, 昆明 650031; 孝感学院物理系, 湖北 孝感 432100
  • 收稿日期:2008-10-29 修回日期:2008-12-02 发布日期:2009-03-31
  • 通讯作者: 张冰 E-mail:bzhang@wipm.ac.cn

Study on Photodissociation Dynamics of n-Pentyliodide Using Velocity Map Ion Imaging

ZHANG Yan, WANG Jun, ZHENG Qiu-Sha, LIU Yu-Zhu, ZHANG Rong-Rong, HU Chang-Jin, TANG Bi-Feng, ZHANG Bing   

  1. State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, P. R. China; Graduate School of the Chinese Academy of Sciences, Beijing 100049, P. R. China; Department of Physics and Technique, Kunming University, Kunming 650031, P. R. China; Department of Physics, Xiaogan University, Xiaogan 432100, Hubei Province, P. R. China
  • Received:2008-10-29 Revised:2008-12-02 Published:2009-03-31
  • Contact: ZHANG Bing E-mail:bzhang@wipm.ac.cn

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摘要： 利用离子速度成像方法对n-C5H11I分子在266和277 nm下的光解动力学进行了研究. 实验分析了I*(5p 2P1/2)和I(5p 2P3/2)的离子影像, 得到其相应速度、角度分布和相对量子产率, 并根据相对量子产率和角度分布计算了不同解离通道的比例. 实验发现n-C5H11I的3Q0和1Q1态之间存在较强的耦合效应, 并且随着波长的减小, 这种非绝热耦合作用有递增的趋势. 由离子影像(I*和I)的角度分布结果发现, 在同一解离激光波长下I*的各向异性参数β值比I的β值小, 其中I*主要由3Q0直接解离产生, 而I绝大多数是由分子先跃迁到3Q0再经过3Q0→1Q1的非绝热耦合产生.

关键词: n-C5H11I, 离子速度成像, 共振增强多光子电离, 相对量子产率

Abstract: Photodissociation dynamics of n-C5H11I at 266 and 277 nm was investigated using velocity map ion imaging. Speed and angular distributions of the corresponding photofragments were obtained by detecting ion images of I*(5p 2P1/2) and I (5p 2P3/2). Quantumyields of I* and Iwere also obtained. The contribution of parallel and perpendicular transitions and the relative fraction of each potential surface at different excitation wavelengths were determined. These determinations were based on the relative quantum yield and the angular distribution. It is found that a very strong nonadiabatic coupling exists between the two excited states 3Q0 and 1Q1, and the curve crossing probability rises gradually with a decrease in the excitation wavelength. Additionally, analysis of the angular distributions for the I* channel and the I channel at the same excitation wavelength revealed that the population of 3Q0 was the main pathway following excitation. However, when compared to the situation that the I* channel mainly results from the direct dissociation of the 3Q0 state, the I channel originates mostly fromthe nonadiabatic coupling between 3Q0 and 1Q1.

Key words: n-C5H11I, Velocity map ion imaging, Resonance-enhanced multiphoton ionization, Relative quantum yield