Beam charge dependence of ion-surface scattering

Evidence is presented that ions retain no information about the incident charge state after they have been scattered from a clean surface. Measurements of oxygen-silicon surface scattering, under conditions which favor binary collisions with individual surface atoms, were found to give the same ratio of negative to positive scattered ions under identical scattering conditions for both an incident ${\mathrm{O}}^{\mathrm{-}}$ ion beam and an incident ${\mathrm{O}}^{+}$ ion beam.