Influence of thermal vibrations on ion surface scattering near 180° scattering angle in the two-atom scattering model

Abstract

Based on the two-atom scattering model, the ion surface scattering near 180° scattering angle is investigated for the analysis of a new ion beam technique, i.e., impact collision ion scattering spectroscopy (ICISS). The shadowing effect of elastic scattering and the ion trajectory focusing effect play important roles for large-angle backscattering at the solid surface. Numerical results show that these two effects are very sensitive to the thermal vibrations of surface atoms, especially to their anisotropy. The angle of incidence at the maximum intensity and the peak width (fwhm) of the backscattering intensity is an increasing function of u z / u x , where u x and u z are the rms displacements parallel to and perpendicular to the surface, respectively. In the case of a TiC crystal, it was found that the ratio of u z / u x is nearly 1.6.