Elastic and inelastic processes in the scattering of positive ions of hydrogen and helium from a LiF surface - art. no. 195411

A theoretical calculation that allows for a fairly complete description of the charge-exchange and surface electronic excitation processes occurring i n the H+ and He+ scattering by ionic surfaces is presented. The interaction parameters required to describe the collisional process are calculated by using a model Hamiltonian that has proved to provide a systematic good desc ription of the properties like binding energy, equilibrium distance, and vi brational frequency of several dimers and atom-surface systems. The formali sm is applied to the comparative study of the scattering of H+ and He+ by t he fluorine atom of a LiF surface. The ion survival probabilities by elasti c and inelastic processes are calculated, and the general trends of the exp erimental findings are reproduced. Very satisfactory results concerning the electron-hole pair excitations in the He+ scattering are obtained when the charge fluctuation on the active F site is considered. The role of the sur face core states is found to be decisive for the e-h pair excitation by He scattering, and for the neutralization of H+ projectiles.