INVESTIGADORES
GARCIA evelina Andrea
congresos y reuniones científicas
Título:
Ion Formation in Hydrogen Scattering from a Graphite Surface
Autor/es:
F. BONETTO; EVELINA A. GARCÍA; R. VIDAL; J. FERRÓN; E. C. GOLDBERG
Lugar:
Foz do Iguazú, Brasil, 15-19 de Noviembre
Reunión:
Congreso; 170 Congresso Brasileiro de Engenharia e Ciencia dos Materiais (170 CEBECIMat); 2006
Resumen:
The enormous
efforts made in trying to understand how Hydrogen interacts with solids are
based, besides its intrinsic basic interest, on its importance as a clean and
renewable source of energy. The energy range of interest is, on the other hand,
extremely wide going from the static one in the H storage devices, up to
thousands of keV in the fusion reactors.
Within this last group, the interaction of energetic H with C seems to
be the most interesting combination since graphite is considered the first
choice as wall material in magnetically confined fusion devices.
In the present
work, we perform both theoretical and experimental studies of the ion formation
during positive H ion scattering on Highly Oriented Pyrolitc Graphite (HOPG),
for a broad range of incoming energies and incident and outgoing angles.
Ion scattering
spectrometry with time of flight analysis is employed to measure the ion
fraction in H+ projectiles scattered from a well characterized HOPG
surface at two fixed scattering angles: 45o and 135o. For
both scattering angles and after analyzing the time of flight spectra, the ion
fraction is determined for several incident energies (in the low keV range) and
outgoing angles.
In the theoretical approach, the
adsorbate-substrate interacting system is adequately described by means of an
Anderson like Hamiltonian where the valence and core surface states are
included. Under the previous assumption of a rapid neutralization of H+
projectiles (mainly related with a resonant electron capture), the positive and
negative ionization probabilities can be calculated by employing a Green's
function formalism to solve the dynamic collisional process.
Both theoretical and experimental
results are analyzed and contrasted for a fixed set of parameters: incident
energy, scattering and outgoing angles. The dependence of the scattered ion
fractions with these parameters is also discussed.