Image Potential State Influence on Charge Exchange in Li⁺–Metal Surface Collisions

Abstract

The energy dependence of the neutral fraction of ions scattered by metal surfaces is observed to be affected by the presence of energy gaps and surface states in their surface band structure. The effect is more dramatic when the ion energy level remains close to the surface Fermi level of the surface, as it occurs in the scattering of Li positive ions by Cu and noble metal surfaces. We have incorporated the interaction of the ion state with the bulk-and surface-like states within an extended Anderson model and by using an ab initio calculation of the Hamiltonian terms. In this form we found that the increase of the neutral fraction at low projectile energies is explained solely by the presence of energy gaps in the case of Cu(111), while the bonding interaction with the first image potential state is also important in the Cu(100), Ag(100), and Ag (111) surfaces.

Quantum beats at the metal/organic interface

“…The potential that results from the image force is critical to the stabilization of molecular energy levels at the interface [50,51] 25 and can influence the surface reactivity of electrons and ions. [52,53] The image-potential also gives rise to a Rydberg series of electronic states (E n ∼ 1/n 2 ) known as the image-potential states (IPS's) [54] which converge to the vacuum level (Fig-30 ure 1). The binding energies, lifetimes, and band structure of the IPS's serve as a sensitive probes of the electronic and structural features that determine the shape of the image-potential.…”

Signals of strong electronic correlation in ion scattering processes

“…The bond-pair model has been successfully used in many different projectile-target combinations [12][13][14][15][16][17]. The atom energy and the hopping terms are obtained from a model Hamiltonian for the atom-surface adiabatic interaction based on both the localized atom-atom interactions and the extended features of the surface states [11].…”

“…In the present work we study the charge transfer between positive ions of Sr and Mg and an Au surface at low incoming energies. Both systems are described by an Anderson Hamiltonian projected over the most probable atomic configurations and the Hamiltonian terms are calculated by using our bondpair model [11], which has proved to be successful in a great variety of interacting systems (see for example [12][13][14][15][16][17] and references therein).…”

Negative ion formation by neutral hydrogen atom grazing scattering from a LiF(100) surface

“…An unoccupied image state (IS) was theoretically conrmed to exist near a LiF crystal surface. 49,50 The image attractive potential created by an electron in front of a dielectric surface may cause an unoccupied image state that can trap an electron close to the vacuum level. Since the image potential is approximately the same at a xed surface altitude over the whole surface, the wave function of the electron in this state can be seen as nonlocal.…”