飞行时间质谱法研究Si（CH3）4分子的多光子解离和电离过程

采用超声分子束技术，以飞行时间（TOF）质谱仪，于410－371nm内，在不同能量的激光作用下，着重检测了气相Si(CH3)4分子在15个波长点处的多光子电离（MPI）TOF质谱分布。根据实验结果，讨论了Si(CH3)4可能的MPI机理，得到了Si^ 主要来自于母体分子及中性碎片的多光子解离－硅原子的共振电离、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、而Si(CH3)4^ 则来自于母体分子的（3＋1）电离的结论。

Study on multiphoton dissociation and lonization process of tetramethylsilane using TOF mass spectroscopic method

Time-of-Flight (TOF) mass spectra distribution of the multiphoton dissociation and ionization of Si(CH 3) 4 in a supersonic molecular beam is investigated with a XeCl excimer laser(308nm) and a tunable dye laser(410-371nm) by a TOF mass spectrometer at the different laser energy irradiation.According to the experimental results,the possible multiphoton ionization (MPI) mechanisms of tetramethylsilane are discussed.We can conclude that the Si + ions might be mainly produced via a sequential photodissociation of parent molecules and neutral molecular fragments to form Si atoms first and followed by a nonresonant or resonant enhanced multiphoton ionization of Si atoms,Si(CH 3) + n(n=1,2,3) ions might be mainly produced via the photodissociation of Si(CH 3) 4 to from neutral molecular fragments Si(CH 3) n(n=1,2,3) first and followed by auto-ionization,whereas Si(CH 3) + 4 ions might be mainly produced from(3+1) ionization of parent molecules.