Interplanar potentials derived from transverse oscillations of 3.5-MeV/amu He and Li nuclei in planar channels of silicon

Transverse oscillations of ions moving in the planar channels of a crystal give information about their stopping powers versus amplitude of oscillation and about the restoring forces operating on the ions. In a previous paper M. T. Robinson has analyzed data on 3-MeV $\alpha$ particles, 10-MeV oxygen ions, and 15-60-MeV iodine ions in crystals of Au; at these energies the effective charges of the ions were unknown and had to be inferred by analysis of the channeling data. In this study we have used light ions at high enough energy to assure that each ion is a bare nucleus. Ions of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$, ${}_{}{}^4{}_{}{}^{}\mathrm{He}$, ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$, and ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$ at 3.5 MeV/amu have been used to give both a change of charge and change of charge-to-mass ratio. Robinson's analysis has been recast since, in this case, the ions' effective charges are known. A new procedure has been utilized to examine how well various approximations for interplanar potentials can be made to fit the data.