BAND EFFECTS ON INELASTIC-SCATTERING OF LOW-ENERGY IONS FROM METALLICAND IONIC SURFACES - A FORMALISM BEYOND THE ADIABATIC MOLECULAR-ORBITALS CALCULATION

Charge exchange and inelastic excitation processes have been analyzed in the scattering of low-energy He+ from metallic and ionic surfaces. An Anderson-like Hamiltonian is proposed, where the parameters are def ined taking into account the electronic band structure of the surface as well as the atomic nature of the interaction between the projectile and the target atoms. The time-dependent collisional process is solve d by using a Green-function formalism, which allows us to calculate no t only the charge-state probabilities but also the one-electron interb and excitations in the solid. Competitive effects of the hybridization s among the localized state at the projectile site and the localized a nd extended surface states are contemplated. in this way we can explai n the observed energy dependences of the neutralization probability, a s well as the occurrence of energy-loss processes due to the excitatio n of valence and core surface electrons induced by the collision.