Assessing electronic energy loss of heavy ions detected in reflection geometry

Abstract

We study energy loss spectra of bromine ions scattered from silver thin films in the energy range of 4 to 36 MeV in forward reflection geometry. The different contributions to the energy loss are analyzed by complementary Monte Carlo simulations. We assess the dependence of the scattering yield and nuclear and electronic losses on the penetration depth of detected ions. For scattering from larger depth, we observe decreased elastic losses and increased trajectory length in comparison with predictions from single scattering, with increasing effects for lower energies. To investigate the entanglement of energy loss and depth information, electronic stopping cross sections are deduced from the experimental spectra by two different approaches: (a) assuming a single scattering model and (b) making use of Monte Carlo simulations. The data obtained from the two approaches are compared, and we assess the relative contributions from nuclear stopping and from the effect of multiple scattering on trajectory length. Results of both methods are discussed in the context of composition depth profiling and compared with data from literature and with Stopping and Range of Ions in Matter (SRIM) predictions resulting in good agreement.