Lattice-constant and electron-affinity effects on negative-ion conversion in atom–ionic-crystal-surface grazing scattering

The effects of the lattice constant and electron affinity on the negative-ion conversion of a neutral atom undergoing grazing scattering on an ionic-crystal surface over the complete velocity range were investigated. Here, a comparison of negative-ion conversion of neutral ${\mathrm{O}}^{0}\text{\ensuremath{-}}\mathrm{KCl}(100),{\mathrm{F}}^{0}\text{\ensuremath{-}}\mathrm{KCl}(100)$, and ${\mathrm{O}}^{0}\text{\ensuremath{-}}\mathrm{KI}(100)$ surface systems shows that the pronounced difference in the efficiency of negative-ion formation between ${\mathrm{F}}^{0}\text{\ensuremath{-}}\mathrm{KCl}(100)$ and ${\mathrm{O}}^{0}\text{\ensuremath{-}}\mathrm{KCl}(100)$ is caused by the large difference in their projectile electron affinities, whereas the difference between ${\mathrm{O}}^{0}\text{\ensuremath{-}}\mathrm{KI}(100)$ and ${\mathrm{O}}^{0}\text{\ensuremath{-}}\mathrm{KCl}(100)$ is caused by the difference in their lattice constants.