DISSOCIATION OF FAST HEH-SURFACE( IONS AT GLANCING ANGLE SCATTERING FROM A CRYSTAL)

Scattered H+ fragments resulting from glancing angle incidence of MeV HeH+ ions on the clean (001) surface of a SnTe crystal are distributed on an ellipse in the E-phi plane, where the angle phi is measured in the plane parallel to the surface and E is the energy of the fragment. The kinetic energies released upon dissociation derived from the diam eters of the ellipses are smaller than those calculated from the explo sion of fully ionized fragments. Based on a simplified model, we have simulated the dissociative scattering of HeH+ ions at the surface, whe re the dissociation takes place via excitation of HeH+ ions and the ch arges of fragments change along the trajectory. It is concluded from t he simulation that the cross section for dissociation in HeH+-electron collisions is of the order of 10(-16) cm2.