Large neutral fractions in collisions of Li+ with a highly oriented pyrolytic graphite surface: Resonant and Auger mechanisms

F. BONETTO; M. ROMERO; EVELINA A. GARCÍA; R. A. VIDAL; J. FERRÓN; E. C. GOLDBERG

PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS

Journal of the American Physical Society

Lugar: USA; Año: 2008 vol. 78 p. 754221 - 754227

0163-1829

We report measurements of neutral atom fractions for Li+ scattered by a HOPG (Highly Oriented Pyrolytic Graphite) surface as a function of the incident ion energy and exit angle. We found an unexpected large neutralization probability that increases with both, energy and exit angle. Based on a dynamical quantum calculation of the scattering process that accounts for the extended features of the surface and the localized nature of the atom-atom interactions, we propose that the resonant neutralization to the Li ground state is a relevant mechanism in this collision. However, to understand the whole process including the angular dependence, and taking into account the Li energy levels variations, we conclude that other mechanisms such as Auger neutralization to the ground state and resonant neutralization to excited states should also be considered.