基于光电子成像技术的碘甲烷多光子电离行为

利用飞秒光电子成像技术研究了碘甲烷在超短激光脉冲场中的多光子电离解离行为.实验获得了碘甲烷分子在400 nm飞秒激光作用下的飞行时间质谱以及电离产生的光电子影像.实验结果表明,在超短脉冲激光场中,分子的电离通常是非共振电离,电离产物主要为母体离子和极少量的碎片离子.从光电子成像中获得的光电子平动能分布可以得到电离产生的电子p_1(2. 03 eV)和p_2(2. 67 eV)分别来源于母体离子的基态和激发态.从光电子成像中获得的角度分布可以推测出,光电子峰p_1和p_2可以分别近似看做单光子电离和双光子电离过程,且光电子散射角度趋于各向同性分布.

Study of the Multiphoton Ionization of Methyl Iodide Based on Photoelectron Imaging Technique

In this paper,the multiphoton ionization dissociation of methyl iodide in ultrashort laser pulse field is studied by using femtosecond photoelectron imaging technology. The time-of-flight mass spectra of iodomethane molecules under 400 nm femtosecond laser and photoelectron images produced by ionization are obtained.The experimental results show that in the ultrashort pulse laser field,the ionization of molecules is usually non-resonant ionization,and the ionization products are mainly parent ions and very few fragment ions. From the photoelectron flat kinetic energy distribution obtained from photoelectron imaging,electrons p_1( 2. 03 eV) and p_2( 2. 67 eV) generated by ionization can be derived from the ground state and excited state of the parent ion,respectively. From the angle distribution obtained in photoelectron imaging,it can be inferred that photoelectron peaks p_1 and p_2 can be approximated as single photon ionization or two photon ionization processes,respectively,and the photoelectron scattering angle tends to be isotropic.