Computer simulation of fast recoil ejection from single crystal surfaces

Abstract

The computer simulation program MARLOWE is used to analyze the most probable surface recoil processes leading to ejection of atoms from (001) gold surfaces subsequent to the irradiation with 20 keV argon atoms. The occurence of two-and threedimensional mechanisms resulting from high-energy recoils involving one and two atomic layers is discussed for atoms ejected in a direction parallel to the plane of incidence. Generally, a close correspondence is found between the mechanisms involved and the features in the energy distributions. The occurence of direct and deflected recoils is confirmed, as well as mechanisms involving the generation of displacements in the two first atomic layers. The dependence of these mechanisms on the conditions of incidence and the ejection direction is investigated. It is suggested that three-dimensional effects, although dominating, mainly contribute to the background in the energy distributions. The intensities in the features in the energy distributions were found to be strongly influenced by shadowing; affecting both the one-and two-layer processes. The influence of thermal vibrations, surface defects and impurities is briefly examined.