Surface channelling and energy losses of 4 keV hydrogen and fluorine ions in grazing scattering on Au(111) and missing row reconstructed Au(110) surfaces

Abstract

We present the results of an experimental and theoretical study of surface channelling and energy loss of 4 keV hydrogen and fluorine ions in grazing scattering on a missing row reconstructed Au(110) surface and a Au(111) surface. We performed measurements of energy losses for grazing angle scattering in surface channelling conditions for various azimuthal orientations of the crystal. Experimental results are discussed in the light of trajectory calculations of hydrogen and fluorine ions scattered under grazing incidence conditions on the surface. A nonlinear model is used in order to calculate the ion energy loss in these crystalline systems. Ab initio electronic crystal structure calculations and semi-classical simulations are performed and allow us to delineate various trajectory classes that correspond to different contributions in the energy loss spectra for various azimuthal orientations of the surface.

Energy loss of keV fluorine ions scattered off a missing-row reconstructed Au(110) surface under grazing incidence

“…Here we give a brief description of how this approach is applied to a fluorine-gold interaction. A more complete description of these simulations is given in our recent work [20,21] and references therein.…”

“…In fluorine scattering electron transfer occurs and we include it semiempirically as described in Ref. [21].…”

“…Its dependence on the local electron density is nonlinear. In our simulations this parameter is taken into account in a stochastic way where, following a normal random distribution for the energy loss straggling in each time step of the particle trajectory; that is, we add or subtract a random amount of energy to the instantaneous energy of the particle according to the local electron density (see [21]). …”

“…Both energy-loss parameters are obtained by solving Schrödinger's equation for the scattering of electrons by a known hydrogeniclike screened potential or a self-consistent potential obtained using the density-functional formalism (DFT) and the transport cross-section (TCS) approach [21].…”

“…Our approach allows us to account for these variations and we are thus able to analyze these energy losses in terms of the ion trajectories and the electron densities encountered. A very brief preliminary account of some results for 4 keV was presented elsewhere [21], along with a description of the theoretical approach we use.…”