390.60nm激光作用下Si(CH3)4的多光子解离与硅原子的(1+1)电离

在390.60nm的紫外激光作用下，利用超声分子束技术与飞行时间（TOF）质谱仪相结合的方法研究了气相四甲基硅分子多光子电离（MPI）的TOF质谱，在较低能量的激光作用下主要检测到了Si(CH3)^ 、Si^ 、C2^ 等离子的信号，有时甚至只检测到了Si^ 离子的信号：在较高能量的激光作用下主要检测到Si(CH3)^ n(n=1,2,3,4)、Si^ 、C2^ 甚至还有SiC3^ ,SiC2^ 等离子的信号。据此并结合以前得到的结论，讨论了四甲基硅分子可能的MPI过程。得出了Si^ 主要来自于Si(CH3)4的多光子解离－Si原子的（1＋1）电离、Si(CH3)n^ (n=1,2,3)的（3＋1）电离、Si(CH3)^ 4来自于Si(CH3)4的（3＋1）电离的结论。

Multiphoton dissociation of Si(CH3)4 and (1+1)ionization of Si at 390. 60nm laser radiation

The time-of-flight (TOF) mass spectra distribution of the multiphoton dissociation/ ionization of tetramethylsilane in a supersonic molecular beam was investigated with a TOF mass spectrometer at 390.6nm laser radiation. In our experiments, TOF mass spectra showed that Si(CH3)+. Si+ C2+ sometimes only Si+, C2+ appeared at lower energy laser radiation but Si(CH3)+ (n=l, 2, 3, 4) , Si+, C2+, even SiC3+, SiO2constantly appeared at higher laser radiation. According to these experimental results, the possible MPI channels of this molecule were discussed. The conclusion was gained that Si+ions might be mainly produced via a sequential photo-dissociation to form Si atoms first and followed by a (1+1) ionization of Si atoms. Si(CH)+n (n=1,2,3)ions might be mainly produced from self-ionization of neutral fragments Si(CH3)n(n=l, 2,3),and the Si+(CH3)4+ions might be produced from (3+1) ioniza.tion of parent molecule.