355nm激光作用下Si(CH<sub>3</sub>)<sub>4</sub>分子的MPI质谱研究

刘玉芳; 施德恒; 孙金锋

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

论文大纲

刘玉芳 ¹施德恒 ^1,2孙金锋 ¹

作者单位

¹ 河南师范大学物理系,河南新乡,453002

² 空军第一航空学院基础部,河南信阳,464000

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.

参考文献

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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.

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