The elastic small angle scattering of ions at atoms in the high energy region. I. Theoretical results

Abstract

In analysing the elastic small angle scattering of ions at atoms in the high energy region it is advantageous to separate the repulsive and the attractive terms of the interaction potential. Both terms dominate the scattering in different ranges of the scattering angle. The repulsive potential leads to undulations in the cross section which are found in the range of approximately=10^-4 to approximately=10^-3 rad for systems of ⁷Li⁺ ions and rare gas atoms at energies about 30 keV. The undulations are caused by the diffraction of the matter waves at the atoms. With this knowledge a simple characteristic correlation between the positions of the undulation extrema and the parameters of the repulsive potential can be given. The undulation effect can be used for determining the repulsive potential term. The influence of the attractive forces between ions and atoms on the small angle scattering is studied for two different attenuated polarization potentials. The calculations show that this potential term has its main influence in the region below the undulation extrema. If the depth of the potential minimum is sufficiently large, the first minimum of the fast oscillations becomes measurable.