FORWARD ELECTRON-EMISSION IN GRAZING ION-SURFACE COLLISIONS

Electrons measured around the direction of specular reflection for 15- 100 keV H+, H-2+, and He+ scattering from single crystals show a stron g dependence of their energy distribution with the surface topography. The maximum of the distribution appears at the convoy electron energy for rough surfaces and shifted to higher energies for smooth surfaces . This energy shift is visible for all the projectiles at 15 keV and i ncreases with ion energy. The results are discussed in terms of transf er to the continuum of the ion Coulomb potential screened by the ion a nd electron surface induced charge.