共振增强多光子电离技术及应用研究

Study on the REMPI and Its Application

原子、分子、离子或自由基在同时吸收m个光子从下态共振跃迁到中间态后再吸收n个光子使其电离的过程中,下态和中间态的多光子共振吸收使得产生的离子信号强度比相应的非共振多光子电离得到的离子信号强度有很大的增强,该过程为共振增强多光子电离(m+n)REMPI。系统研究了共振增强多光子电离技术的应用、特点和基本原理,包括跃迁选择定则、电子态的光解离机理、描述REMPI过程的速率方程等,并阐述共振增强多光子电离-时间飞行质谱的实验装置,实验方法和实验流程。共振增强多光子电离技术在研究原子、分子或自由基的较高电子激发态特性方面发挥着重要作用。

Atoms, molecules, ions or radicals can be excited to a intermediate state by the absorption of mlaser photons, and then the parent ion can be produced by absorption of another n-laser photons. Compared with the non-resonant absorption, the ion signal intensity can be increased drastically due to the resonant absorption between the intermediate states and the lower state. This rnultiphoton process is usually called Resonance Enhanced Muhiphoton Ionization （REMPI）. The applications and characteristics of REMPI technique is systematically studied, and the basic principles of REMPI technique are introduced, which includes the selection rules of transition, the mechanism of photoionization and photodissociation, REMPI rate equation etc. REMPI technique plays an important role in detecting the high electronic excited states of atoms, molecules and radicals. The experimental setup and the experimental method and the experimental processes and procedures of REMPI-TOF technique are presented.