INTEC   05402
INSTITUTO DE DESARROLLO TECNOLOGICO PARA LA INDUSTRIA QUIMICA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Charge transfer in collisions of KeV Li+ ions with Copper surfaces.
Autor/es:
C. MEYER; R. VIDAL; J. FERRÓN; F. BONETTO; E. A. GARCIA; E. C. GOLDBERG
Lugar:
Aguas de Lindoia, Sao Paulo, Brasil
Reunión:
Encuentro; XXXV Encontro Nacional de Fisica da Materia Condensada; 2012
Institución organizadora:
Sociedade Brasileira de Fisica
Resumen:
Charge transfer between an atom (ion) and a surface is a very complex phenomenon whose implications extend over a large number of different fields, going from chemical reactions, as in catalysis for instance, to electron emission and surface characterization. The interaction between slow ions and a surface is a basic phenomenon that has received a lot of attention. However, and despite the enormous amount of work devoted to the subject, new exciting experiments and theoretical models keep promoting a lot of debate. Here, we report measurements of neutral atom fractions for Li+ scattered by Cu(111) and Cu(100) surfaces as a function of the exit ion energy and exit angle. Large neutralization rates (between 20% and 60%) are found in all cases. A first-principles quantum mechanical based theoretical formalism is applied to describe the time dependent scattering process, where neutralization to the Li ground state is considered as the unique relevant charge transfer channel during the collision. The rising of the neutralization fraction as the exit energy decreases is reasonable well described by the model. The proximity of the projectile energy level to the solid Fermi level and the large extension of the ion-surface coupling interactions (requiring consideration of a large number of atoms in the surface) play a decisive role in explaining the dependences and the neutralization magnitudes observed.