A tracking algorithm for Monte Carlo simulation of surface roughness in EPMA measurements

Abstract

We present an algorithm for Monte Carlo simulation of particle trajectories through rough interfaces. The microscopic topography of the rough surface is assumed to be described by an altitude map in a dense rectangular grid. The tracking algorithm has been implemented in a Fortran subroutine package, which is coupled to the code system PENELOPE/PENEPMA to perform Monte Carlo simulations of X-ray emission from samples with rough surfaces irradiated by electron beams. To validate the numerical procedure, electron probe microanalysis (EPMA) simulations of an ideal sample with periodic surface roughness have been performed by using 1) the PENGEOM geometry package of the PENELOPE code system and 2) the new tracking algorithm. The results from the two simulations are found to be equivalent, that is, their differences are generally less than the associated statistical uncertainties. Results from simulations of samples with realistic rough surfaces are also presented.