Role of Electron Correlation in Charge Transfer to Atoms Leaving Metal Surfaces

Abstract

The fraction of atoms which appear in a charge state different from the dominant adiabatic (usually neutral) one after scattering or sputtering from a metal surface is calculated. We use a time-dependent Anderson Hamiltonian with an intraatomic Coulomb repulsion term. An approximate solution is found by using only a small subset of electronic states. The intraatomic correlation is taken into account by not allowing double occupation of the atomic orbital. The dependence of the non-adiabatic fraction upon the atom velocity v is similar to the one found by using a non-interacting Hamiltonian, and is proportional to exp (–c/v). Some experimental results are discussed, but true quantitative comparison is at present not possible.