物理化学学报 >> 2015, Vol. 31 >> Issue (9): 1662-1666.doi: 10.3866/PKU.WHXB201507061

热力学,动力学和结构化学 上一篇    下一篇

飞秒时间分辨的光电子谱对苯S2态的超快动力学研究

沈环1,*(),张冰2   

  1. 1 华中农业大学理学院,武汉430070
    2 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
  • 收稿日期:2015-04-10 发布日期:2015-09-06
  • 通讯作者: 沈环 E-mail:shenhuan@mail.hzau.edu.cn
  • 基金资助:
    国家自然科学基金(21403080)

Ultrafast Dynamics of Benzene on the S2 State Investigated by Femtosecond Time-Resolved Photoelectron Spectroscopy

Huan. SHEN1,*(),Bing. ZHANG2   

  1. 1 College of Science, Huazhong Agricultural University, Wuhan 430070, P. R. China
    2 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
  • Received:2015-04-10 Published:2015-09-06
  • Contact: Huan. SHEN E-mail:shenhuan@mail.hzau.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(21403080)

摘要:

结合飞秒时间分辨的质谱技术与时间分辨的光电子影像技术对苯S2激发态的超快动力学进行了研究.苯分子吸收两个400 nm的光子被激发到S2态,之后再用一个267 nm的光子对其进行探测.获得的母体离子产率随泵浦探测时间延迟的变化曲线包含了两个不同的时间寿命组分.第一个时间寿命组分(90 ± 1) fs被归纳为S2态到S1/S0态的内转换过程;第二个时间寿命组分(5.0 ± 0.2) ps被归纳为S1态的衰减过程.实验中观察到的第二个寿命组分小于早前的研究结果,这表明了在S1态的衰减过程中还可能存在其他的过程.从时间分辨的光电子影像提取得到的光电子能谱中发现了一个新的失活过程,该过程被归结为激发态S1的振动态与“热”三重态T3之间的系间交叉过程.

关键词: 时间分辨, 光电子能谱, 苯分子, 内转换, 系间交叉

Abstract:

The ultrafast dynamics of benzene on the S2 state have been investigated by femtosecond time-resolved mass spectroscopy coupled with photoelectron imaging. The benzene molecule was excited to the S2 state by two 400 nm photons, and subsequently probed by one 267 nm photon. The timedependent ion yield of the parent ion consists of two components with different lifetimes. The first component at (90 ± 1) fs is because of internal conversion from the S2 state to the S1/S0 state. The second one, i.e., (5.0 ± 0.2) ps, is due to decay of the S1 state. The observed lifetime of the second component is shorter than previous results, indicating the existence of an additional decay process. With photoelectron spectra extracted from the time-resolved photoelectron imaging, this newly found deactivated process is assigned to intersystem crossing from the vibrational excited S1 state to the hot triplet state T3.

Key words: Time-resolved, Photoelectron spectroscopy, Benzene molecule, Internal conversion, Intersystem crossing

MSC2000: 

  • O644