Vibronic dynamics of o-dichlorobenzene in its lowest excited singlet state, S₁, is investigated in real time by using femtosecond pump-probe method, combined with time-of-flight mass spectroscopy and photoelectron velocity mapping technique. Relaxation processes for the excitation in the range of 276 to 252 nm can be fitted by single exponential decay model, while in the case of wavelength shorter than 252 nm two-exponential decay model must be adopted for simulating transient profiles. Lifetime constants of the vibrationally excited S₁ states change from 651±10 ps for 276 nm excitation to 61±1 ps for 242 nm excitation. Both the internal conversion from the S₁ to the highly vibrationally excited ground state S₀ and the intersystem crossing from the S₁ to the triplet state are supposed to play important roles in de-excitation processes. Exponential fitting of the de-excitation rates on the excitation energy implies such de-excitation process starts from the highly vibrationally excited S₀ state, which is validated, by probing the relaxation following photoexcitation at 281 nm, below the S₁ origin. Time-dependent photoelectron kinetic energy distributions have been obtained experimentally. As the excitation wavelength changes from 276 nm to 242 nm, different cationic vibronic vibrations can be populated, determined by the Franck-Condon factors between the large geometry distorted excited singlet states and final cationic states.

利用飞秒泵浦探针方法，结合飞行时间质谱和光电子速度映射技术，实时研究了处于最低激发单重态S ₁的邻二氯苯的动力学。276至252 nm范围内激发的弛豫过程可以通过单指数衰减模型拟合，而在波长小于252 nm的情况下，必须采用两指数衰减模型来模拟瞬态曲线。振动激发的S ₁状态的寿命常数从276 nm激发的651±10 ps变为242 nm激发的61±1 ps。从S ₁到高振动激发基态S ₀的内部转换并且从S ₁到三重态的系统间交叉在去激过程中起着重要作用。消除激发速率与激发能量的指数拟合表明，这种消除激发过程是从高度振动激发的S ₀状态开始的，通过探测在281 nm处的光激发后在S ₁起点以下的弛豫可以验证这种消除激发的过程。通过实验获得了随时间变化的光电子动能分布。随着激发波长从276 nm变为242 nm，可以填充不同的阳离子振动，这由大几何形状扭曲的激发单重态和最终阳离子态之间的Franck-Condon因子决定。