Attarian Shandiz M, Salvat F, Gauvin R
Department of Materials Engineering, McGill University, Montreal, Canada.
Facultat de Fisica (ECM), Universitat de Barcelona, Barcelona, Spain.
Scanning. 2016 Nov;38(6):475-491. doi: 10.1002/sca.21280. Epub 2015 Oct 29.
A computer program for detailed Monte Carlo simulation of the transport of electrons with kinetic energies in the range between about 0.1 and about 500 keV in bulk materials and in thin solid films is presented. Elastic scattering is described from differential cross sections calculated by the relativistic (Dirac) partial-wave expansion method with different models of the scattering potential. Inelastic interactions are simulated from an optical-data model based on an empirical optical oscillator strength that combines optical functions of the solid with atomic photoelectric data. The generalized oscillator strength is built from the adopted optical oscillator strength by using an extension algorithm derived from Lindhard's dielectric function for a free-electron gas. It is shown that simulated backscattering fractions of electron beams from bulk (semi-infinite) specimens are in good agreement with experimental data for beam energies from 0.1 keV up to about 100 keV. Simulations also yield transmitted and backscattered fractions of electron beams on thin solid films that agree closely with measurements for different film thicknesses and incidence angles. Simulated most probable deflection angles and depth-dose distributions also agree satisfactorily with measurements. Finally, electron energy loss spectra of several elemental solids are simulated and the effects of the beam energy and the foil thickness on the signal to background and signal to noise ratios are investigated. SCANNING 38:475-491, 2016. © 2015 Wiley Periodicals, Inc.
本文介绍了一种计算机程序,用于详细的蒙特卡罗模拟,该模拟可计算动能在约0.1至约500keV范围内的电子在块状材料和固体薄膜中的传输情况。弹性散射通过相对论(狄拉克)分波展开法计算的微分截面来描述,该方法采用了不同的散射势模型。非弹性相互作用则根据基于经验光学振子强度的光学数据模型进行模拟,该模型将固体的光学函数与原子光电数据相结合。广义振子强度通过使用从林哈德自由电子气体介电函数导出的扩展算法,由采用的光学振子强度构建而成。结果表明,对于能量从0.1keV到约100keV的电子束,模拟得到的块状(半无限)样品的背散射分数与实验数据吻合良好。模拟还得出了电子束在固体薄膜上的透射和背散射分数,这些结果与不同薄膜厚度和入射角下的测量结果非常吻合。模拟得到的最可能偏转角和深度剂量分布也与测量结果令人满意地相符。最后,模拟了几种元素固体的电子能量损失谱,并研究了束能量和箔厚度对信号背景比和信噪比的影响。《扫描》38:475 - 491, 2016。© 2015威利期刊公司。