甲基自由基在212.5 nm的光分解:母体内能态的激发对产物态分布的影响

摘要

Photodissociation dynamics of the CH3 radical at 212.5 nm excitation has been studied experimentally using the H atom Rydberg tagging time-of-flight method. CH3 radicals are produded by photodissociation of CH3I at 266 nm. Translational energy distribution and angular distribution for the CH2 product from CH3 photodissociation at different vibrational levels via the 3s Rydberg state have been measured. From these distributions, product J state distributions are obtained for photodissociation of different vibrationally excited CH3 radicals. The effect of parent vibrational as well as rotational excitation on the dissociation dynamics of CH3 is also investigated in detail. Experimental results in this work show that parent vibrational excitation in the umbrella mode has a significant effect on both rotational excitation and angular distribution of the CH2 product, while parent rotational excitation has obvious effect only on the angular distribution of CH2 product.%利用里德堡氢原子飞渡时间谱的方法,进行了甲基自由基在212.5 nm的光解动力学的实验研究.甲基自由基来自于碘甲烷分子在266 nm的光分解.实验测量了不同振动态的甲基自由基通过3s电子激发态解离的产物CH2自由基的平动能分布和角分布,并从平动能分布得到了CH2自由基的转动布居.实验同时详细地研究了母体分子甲基自由基的振动和转动激发对光解动力学的影响.实验结果表明母体分子甲基自由基的伞形振动对于产物的转动激发和角分布均有较大的影响,而母体分子的转动激发只对产物的角分布有较明显的影响.