中国激光, 2002, 29 (3): 218, 网络出版: 2006-08-08
355nm激光作用下Si(CH3)4分子的MPI质谱研究
Multiphoton Ionization Mass Spectra Study of Tetramethylsilane at 355 nm Laser Radiation
四甲基硅 多光子解离电离 多光子电离解离 反应动力学 质谱 tetramethylsilane multiphoton dissociation followed by multiphoton multiphoton ionization followed by multiphoton di chemical kinetics mass spectra
摘要
在355 nm的激光作用下,利用扩散分子束技术和四极质谱装置相结合研究了气相Si(CH3)4分子多光子电离(MPI)质谱分布.测量了Si(CH3)+4,Si(CH3)+3,Si(CH3)+2,Si(CH3)+及Si+离子的激光光强指数,检测了这5种碎片离子的信号强度占总信号强度的分支比随光强的变化关系.据此,讨论了该分子MPI过程可能经历的通道,得到了Si+主要来自于母体分子的多光子解离-硅原子的电离,Si(CH3)+n(n=1,2,3)主要来自于中性碎片Si(CH3)n(n=1,2,3)的自电离,Si(CH3)+4来自于母体分子的(3+1)电离的结论.
Abstract
Multiphoton ionization (MPI) mass spectra distributions of tetramethylsilane in gaseous phase are investigated using a quadrupole mass spectrometer and a pulsed molecular beam at 355 nm laser radiation. The dependence of the signal intensity of the ions Si(CH 3) + n (n=1,2,3,4) and Si + on laser power is measured. The fractions of signal Si(CH 3) + n(n=1,2,3,4) and Si + vs. laser intensity are obtained. According to these, the possible MPI channels and the chemical kinetics mechanisms of this molecule are discussed. The conclusion is gained that Si + ions might be mainly produced via a sequential photo-dissociation to form Si atoms first and followed by a multiphoton ionization of Si atoms, Si(CH 3) + n(n=1,2,3) ions might be mainly produced from self-ionization of neutral fragments Si(CH 3) n, and the Si(CH 3) + 4 ions might be produced from (3+1) ionization of parent molecules.
刘玉芳, 施德恒, 孙金锋. 355nm激光作用下Si(CH3)4分子的MPI质谱研究[J]. 中国激光, 2002, 29(3): 218. 刘玉芳, 施德恒, 孙金锋. Multiphoton Ionization Mass Spectra Study of Tetramethylsilane at 355 nm Laser Radiation[J]. Chinese Journal of Lasers, 2002, 29(3): 218.