物理化学学报 >> 1993, Vol. 9 >> Issue (04): 495-500.doi: 10.3866/PKU.WHXB19930414

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氯分子束与InP(100)表面反应散射的角分布研究

卢平和; 秦启宗   

  1. 复旦大学 激光化学研究室，上海 200433
  • 收稿日期:1992-02-11 修回日期:1992-07-02 发布日期:1993-08-15
  • 通讯作者:

Angular Distribution Studies on the Reactive Scattering of Cl2 Molecular Beam with InP(100) Surface

Lu Ping-He; Qin Qi-Zong   

  1. Laser Chemistry Laboratory, Fudan University, Shanghai 200433
  • Received:1992-02-11 Revised:1992-07-02 Published:1993-08-15
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摘要： 采用角分辨分子束散射技术研究了Cl_2与InP(100)表面热反应和激光诱导反应产物的角分布. 对于热反应, 由调制分子束和可转动四极质谱仪测得产物离子InCl~+、InCl_2~+、PCl~+、PCl_2~+和P_4~+的角分布, 都可用cos~(1.5)θ函数报合. 对于紫外(355 nm)激光诱导反应, 由飞行时间质谱法测得主要产物离子的角分布明显地偏离Knudsen定律. 其中In~+, InCl~+和InCl_2~+的角分布可用α·cosθ+(1-α)cos~nθ函数拟合, 其中α和n为拟合参数, 对于不同的产物离子有不同的数值. 由实验测得的脱附粒子的通量和能量在表面法线方向有明显地聚集现象, 可以认为产物从表面上脱附的机理, 除了热脱附之外, 还有非热脱附以及在表面附近脱附粒子的碰撞效应.

关键词: 分子束, 反应散射, 飞行时间谱, InP

Abstract: Angle-resolved supersonic molecular beam scattering techniques are used to examine the angular distributions of the products formed in thermal and UV laser-induced reactions of chlorine molecular beam with InP(100) surface. For the thermal reaction, the angular distributions of InCl_2~+, InCl~+, PCl~+, PCl_2~+ and P_4~+ products are slightly peaked towards the normal of the surface and vary as cos~(1.5)θ, θ being the detection angle from the surface normal. The effect of the normal components of the transla-tional energies of Cl_2 molecules is also observed at different angle of incidence. Under 355 nm pulsed laser irradiation, the time-of-flight (TOF) spectra of InCl~+ are measured as a function of the detection angle and Maxwellian characterized with the mean kinetic energy or translational temperature. The flux distributions are sharper than cosine law and can be fitted by an expression of F(θ)=a·cosθ+(1-a)cos~nθ, where a and n are adjustable parameters. The mean kinetic energy distribution of InCl molecules is strongly peaked around the surface normal and decreases with increasing the detection angle. These results imply that both thermal and nonthermal desorption mechanisms are important in the UV laser-induced reaction processes.

Key words: Molecular beam, Reactive scattering, Time-of-flight spectra, InP