大气污染物，尤其是有机挥发污染物(VOCs)，在太阳光辐射下发生光物理光化学反应，对大气环境有严重破坏作用。借助于飞秒激光抽运-探测技术和光电子成像探测技术，可以在飞秒时间尺度和分子空间尺度追踪VOCs 分子在吸收光子后发生的微观光物理光化学反应过程，深入认识其动力学过程，对大气环境的进一步保护有着重要的意义。结合近三年在该方向的研究成果，概述了研究进展，描述了为该实验搭建的双极光电子成像平台，并介绍了几个实验结果：乙苯分子电子激发态的超快光弛豫动力学；二甲苯分子第二电子激发态的超快系间蹿跃和超快内转换动力学；呋喃分子吸收光子后的超快光致异构化过程；氟利昂F-113 分子的多光子解离动力学。

Photophysical and photochemical reactions of air pollutants induced by sunlight radiation, particularly volatile organic contaminants (VOCs), have serious damaging effects on atmospheric environment. Via femtosecond pump-probe technique and photoelectron imaging detection technology, these photophysical and photochemical reactions in the femtosecond time scale and molecular space scale aretracked. Detailed dynamics are obtained for understanding, which are significant for further protection of the atmospheric environment. Combining with the results of nearly three years in the direction, the research progresses of this direction are summarized. The doublesided photoelectron imaging setup and experimental platform for these measurements are described. Several recent experimental results are introduced: ultrafast relaxation dynamics of the excited states of ethylbenzene; ultrafast competing intersystem crossing and internal conversion in the S2 state of o-xylene; photoisomerization dynamics of furan; multiphoton dissociation dynamics of Freon 113.