IFIS - LITORAL   24734
INSTITUTO DE FISICA DEL LITORAL
Unidad Ejecutora - UE
congresos y reuniones científicas
Understanding charge transfer processes in low energy collisions between Li+ ions and metallic surfaces.
F. BONETTO; E. A. GARCIA; E. C. GOLDBERG
Aguas de Lindoia, San Pablo, Brasil
Encuentro; XXXVI Encontro Nacional de Fisica da Materia Condensada; 2013
Sociedade Brasileira de Fisica
A first principles quantum-mechanical formalism is applied to describe the charge transfer produced in low energy collisions between a Li+ incident ion and various metallic surfaces. In this approach, the resonant neutralization to the fundamental state (Li-2s) is considered as the unique charge transfer channel available during the whole collision process. All the physical ingredients involved on the dynamic problem analyzed, such as the crossed terms of the density matrix of the surface solid, the number of surface atoms considered in the theoretical approach, the presence of the surface and image states and the change in the energy level (and its width) relative to the target surface Fermi level are discriminated and its in°uence on the partial and ¯nal charge states are thoroughly examined. The analysis is focused on Cu(111), Cu(100) and Ag(111) and the results are contrasted with previously reported experimental data. Despite the in°uence of each mechanism strongly depends on the particular surface studied, certain character- istics are found to be common to all the targets: i) the projectile charge state is mainly de¯ned on the exit trajectory, being the ¯nal part of the trajectory specially relevant(distances larger than 14 u.a.) for lower ener- gies; ii) the inclusion of the crossed terms of the density matrix introduces a signi¯cant change on the projectile energy level and width, leading to relevant changes in the neutralization curve on the whole range of incoming energies, iii) the introduction of a large number of surface atoms to describe the solid target is crucial to explain the signi¯cant growing on the neutral fraction experimentally observed at lower energies and iv) the image state contributes to a better description of the neutralization curved observed.