INVESTIGADORES
GARCIA evelina Andrea
congresos y reuniones científicas
Título:
Image potential state influence on charge exchange in Li+-metal surafce collisions
Autor/es:
F. BONETTO; EVELINA A. GARCÍA; E. C. GOLDBERG
Lugar:
Santa Fe
Reunión:
Congreso; Congreso Internacional de Metalurgia y Materiales (SAM-CONAMET/IBEROMAT 2014); 2014
Resumen:
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.
When
compared to experimental data, the introduction of image potential states
clearly improves the calculation in all cases. This constitutes an evident step
up in the description of charge transfer during ion-metal surface collisions. A
better description of the experimental neutralizations vs. energy dependence is
obtained after orthogonalization of Li2s and image state wave functions.
However, no significant differences in the magnitude of neutral fractions are
found. Main changes introduced by the image potential state in the
neutralization rates are totally defined in the last part of the outgoing
trajectory (ion-surface distance larger than 9 a.u.).