Complete negative-ion conversion of halogen atoms and positive ions in surface scattering from KI(100)

Fast positive ions and atoms with energies ranging from some 100 eV to 100 keV are scattered under a grazing angle of incidence from a clean and flat (100) surface of a monocrystalline KI sample. We observe for halogen projectiles an almost complete negative-ion conversion, i.e., negative-ion fractions up to 98.5%. Our data show a characteristic dependence on the projectile velocity, which provides important additional information on the mechanisms of formation of negative ions in the scattering from the surface of an insulator. copyright 1996 The American Physical Society