中文摘要：

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-氯吡啶分子激发态的超快过程. 实时观察到了2-氯吡啶分子第二激发态（S2）向第一激发态（S1）高振动能级的的超快内转换过程，该内转换的时间常数为（162±5）fs. 实验结果表明, 通过S2/S0的锥形交叉衰减到基态的衰减通道也是退布居的重要通道, 其时间尺度为（5.5±0.3） ps.

英文摘要：

Ultrafast internal conversion dynamics of 2-chloropyridine were studied by femtosecond time-resolved photoelectron imaging spectroscopy coupled with time-resolved mass spectroscopy. The ultrafast internal conversion from the second excited state （S2） to the first excited state （S1） via an adjacent conical intersection within （162±5） fs was clearly observed from the time-dependence of the photoelectron spectra. The subsequent deactivations involved the coupling of S2/S0 （the ground state） and S1/S0 conical intersections, which occurred on a timescale of about （5.5±0.3） ps, and led to the internal conversion to the ground state from the S2 and S1 states.