A new weighted Monte Carlo algorithm for elastic electron backscattering from surfaces

When a monoenergetic electron beam bombards a solid target, some electrons are backscattered without energy loss. This elastic electron backscattering effect plays an important role in many experimental techniques, like low-energy electron diffraction, scanning electron microscopy and others. Recently, the elastic peak has been used for the experimental determination of electron inelastic mean free paths (IMFPs) in the solid. This experimental determination (which is now considered as the most reliable [J. Phys. Chem. Ref. Data 28 (1999) 19] consists in comparing the measurement to a model calculation in which the IMFP is a parameter. In most cases for the model calculation, a simple non-analog Monte Carlo simulation (where the inelastic events are considered as absorptions and taken into account by a weight) is used. In many cases, long computational times are needed, especially when the solid angle of the electron detector is small. In this work, we introduce a new weighted Monte Carlo algorithm, which combines several techniques for variance reduction. Results of extensive numerical tests are presented, demonstrating the increased effectiveness of the new algorithm.