DYNAMICS OF RESONANT CHARGE-TRANSFER IN LOW-ENERGY ALKALI-METAL-ION SCATTERING

We show in this paper that measurements of charge-state distributions for 5-1600 eV Li, Na, and K scattered from a clean Cu(001) surface provide an excellent probe of the dynamics of atom-surface charge transfer. The neutralization probabilities, measured as a function of the perpendicular velocities of the scattered atoms, are qualitatively different for the three species. These differences reflect the high sensitivity of the charge transfer in this energy range to the energies and lifetimes of the atomic resonances near the surface. The measured neutralization probabilities are found to depend on the parallel velocity component of the scattered atom, even though the velocities at which these experiments are conducted are relatively low. The data are compared to several models of the charge-transfer process. Agreement with the data is achieved using a model based on the one-electron Newns-Anderson Hamiltonian and using calculated values for the alkali-metal resonance parameters.