Jl. Rousset et al., ION-SCATTERING STUDY AND MONTE-CARLO SIMULATIONS OF SURFACE SEGREGATION IN PD-PT NANOCLUSTERS OBTAINED BY LASER VAPORIZATION OF BULK ALLOYS, Physical review. B, Condensed matter, 58(4), 1998, pp. 2150-2156
Bimetallic Pd-Pt clusters deposited on amorphous carbon have been prod
uced by laser vaporization of various bulk alloys. Energy dispersive x
-ray analysis and transmission electron microscopy show that they have
a perfectly well-defined stoichiometry and a narrow range of size. Th
ey constitute ideal systems to investigate segregation processes in fi
nite solids. It is shown that low-energy ion scattering allows the det
ermination of surface concentration, which has been found to be differ
ent from the overall one. Monte Carlo simulations coupled with a recen
tly developed energetical model, based on a tight-binding scheme that
includes bond strength modifications at surfaces, account well for the
experimental finding and give information on the surface distribution
of the segregating Pd atoms.