Influence of Coulomb Repulsive Interaction and Image Potential on Electron Tunneling between Alkali-Metal Ions and Solid Surfaces

On the basis of numerical results obtained by solving simultaneous differential equations derived from the Heisenberg equation of motion, we examined the influence of the Coulomb repulsive interaction and image potential on the ion survival probability (ISP) of Cs+ ions. In these calculations, the time-dependent Anderson-Newns model was evaluated, assuming the Hartree-Fock approximation for the many-body term. Comparison with experimental data revealed that the calculated ISPs for Cs+ ions displayed quantitative correspondence with the experimental data in the presence of a weak time-dependent Coulomb repulsive interaction. In contrast, the introduction of the exact image potential appeared less important for fitting the calculated and experimental data. Furthermore, the numerical data were compared with data obtained using the Landau-Zener formula, revealing good agreement when the interaction between the surface and atoms was weak.