MULTIPLE-SCATTERING IN THE INTERACTION OF LOW-ENERGY IONS WITH A COLD AU SURFACE COVERED BY A FILM OF CONDENSED ARGON

Energy spectra of ions emitted from a cold (< 40 K) Au surface covered by a thin film of condensed argon at small scattering angles (including the case of specular reflection) were examined. Depending on the density of the film new effects such as a splitting or shifting df the gold quasi-single-scattering peak are observed. It is postulated that these effects are connected with multiple scattering of projectiles inside the adsorbed film. Multiple scattering directs the ions to the detector after single scattering from the substrate atoms over the angles larger or smaller than the detection angle. At a certain density of adsorbed film only large-angle substrate scattering occurs. This phenomenon is manifested experimentally by a shift of the gold quasi-single-scattering peak.