紫外激光作用下环氧乙烷的TOF质谱研究

UV laser MPID time-of-f light mass spectra study on Oxirane

本文采用超声分子束技术,分别在308nm和355nm的紫外激光下,对环氧乙烷分子进行了多光子电离飞行时间(TOF)质谱研究.在308nm激光作用时,观测到C_2H_4O^+、C_2H_3O_+、CHO^+和CH_3^+等离子的信号;在355nm激光作用时,则没有观测到分子离子的信号.在两种激光作用下最强的信号都是CHO^+.但是两种激光下各碎片离子信号的光强指数有一定差别,表明在两种情形下,环氧乙烷分子经历了不同的电离解离过程.

We studied the Multiphoton Ionization Dissociation (MPID) time-of-flight mass spectra of oxirane with ultrasonic molecular beam system at 308 nm and 355 nm laser radiation. In our experiments, the mass spectra distributions showed a certain extend of difference between two conditions. Under 355 nm laser radiation, there is no molecular ion signal and under 308nm we got a high laser intensity index for each fragment ions. Differing from electron impact ionization, the most intensive ion signal came from CHO+. With the laser intensity dependence of each fragment ion and its branch ratio we investigated the MPID process and mechanism of Oxirane at these two laser radiatios.