Surface Scattering of Low Energy Ions

Abstract

Angular and energy distributions of Ne⁺ ions (200 eV to 2 keV) backscattered from Ni(110) and (111) surfaces were measured and compared with numerical calculations. In the energy distributions peaks due to multiple and single scattering events can be identified. Multiple scattering occurs between a minimum and a maximum scattering angle. Experimentally, both angles depend on the lattice parameters, the angle of incidence, the energy and the ion-atom combination. These effects are qualitatively understood in the atomic chain model of multiple scattering. The main discrepancies between model and experiment are slight shifts of the measured energies towards lower values and deviations of the maximum scattering angle towards higher values. The angular deviation can be accounted for by fitting the screening length in the Molière approximation of the Thomas-Fermi potential, which was used for the calculations. The screening length thereby obtained is about 30% below the theoretical value of Lindhard. A comparison with other potentials from the literature indicates that the potential determined here is within theoretical expectations.