Nuclear versus electronic energy loss in slow Ar ion scattering on a Cu (100) surface: Experiment and simulations

In the scattering and stopping of heavy ions on a few surface layers in solids, contributions of the electronic and nuclear energy losses can become comparable. In this work we present a study of 0.6--5-keV Ar ion scattering on a Cu (100) surface. Energy-loss spectra were measured and displayed some changes as the incident ion energy changes. Thus, a structured spectrum is observed at the higher energies. We analyze the characteristics of the spectra and contributions from the nuclear and electronic energy-loss components using both a Monte Carlo kinetics simulation assuming an averaged electron density and a semiclassical deterministic simulation with an inhomogeneous electron density in the solid. The general features of the experimental spectra were well reproduced, and semiclassical simulations allow us to identify contributions from trajectories coming from below and on top of the surface atomic layer. The relative contribution of nuclear energy loss and electronic energy loss (EEL) were delineated and a more refined analysis of the EEL for different trajectories is presented.