INVESTIGADORES
ASCOLANI Hugo Del Lujan
artículos
Título:
Adsorption of short-chain alkanethiols on Ag(111) studied
Autor/es:
L.M. RODRÍGUEZ; J.E. GAYONE; E.A. SÁNCHEZ; H. ASCOLANI; O. GRIZZI; M. SÁNCHEZ; B. BLUM; G. BENITEZ; R.C. SALVAREZZA
Revista:
SURFACE SCIENCE
Editorial:
Elsevier
Referencias:
Año: 2006 vol. 600 p. 2305 - 2316
ISSN:
0039-6028
Resumen:
We use direct recoiling spectroscopy with
time-of-flight analysis to study the adsorption of propanethiol on Ag(111)
cleaned and polished in vacuum by cycles of grazing ion bombardment and
annealing. We discuss the advantages and drawbacks of the technique to follow
the growth of the organic film. In particular, the low damage imparted by the
technique allows to follow in detail the evolution of the H, C and substrate
recoiling peaks for a wide range of exposures ranging from 10_1 to 2 · 104 L. The shape of the TOF spectra and the
evolution of the recoiling intensities are consistent with a growth process in three stages: an initial fast one related to the density
of defects at the surface, a second one where the surface is covered with a
thin layer of organic molecules, presumably associated with lyingdown molecules,
and a final stage corresponding to a thicker layer that can be associated with
a standing-up orientation of the molecules in the film. Annealing of the
organic film to 250 _C produces complete depletion of C and H,
leaving a small amount of S. The final S
coverage after annealing depends on the
initial roughness, being higher for rougher surfaces. We also observe an
increase in the surface roughness after desorption of the thiol layer. Re-adsorption
on this post annealed surface presents a marked enhancement of the initial sticking.