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He reflectivity study of a self-assembled monolayerof decanethiol on Au(1 1 1)
No full textWe present a study of a self-assembled monolayers of decanethiol on Au(1 1 1) performed by means of low energy
He beam scattering. Full monolayers of standing up molecules have been grown at 275 K in ultra high vacuum and the
measurements have been performed between 40 and 60 K. In particular, specular reflectivity has been measured before
and after an annealing to 360 K and features associated to resonances with bound states of He atom interacting with the
CH3 groups of the standing-up organic molecules have been observed. Through the analysis of the angular position of
these features four bound state levels have been determined. The comparison between the levels of the as-deposited
monolayer and those of the annealed one shows that the two spectra are very similar and only differ slightly on the value
of the deepest level
Spectrum of the interaction potential between He and as-deposited self-assembled monolayers of decanethiol chemisorbed on Au(111)
No full textMechanism of adatom formation on Ag(110) studied by combined quasi-elasticHe atom scattering and low energy ion scattering
No full textTwo complementary techniques, i.e. low-energy ion scattering in the neutral impact collision ion scattering spectroscopy
(NICISS) mode and energy resolved He atom scattering (HAS) are combined to study the adatom formation
mechanism on Ag(110). The NICISS spectra have been collected between 300 and 900 K along the ,
and azimuthal directions while HAS measurements of the diffuse elastic peak has been performed along the
directions between 190 and 800 K. Both techniques are sensitive to surface disorder and HAS data have been
corrected by using the NICISS results in particular on the anharmonicity estimated through a two atoms scattering
model. In fact, above 500 K surface anharmonicity is clearly detected and accompanies the proliferation of thermal
induced defects. Without this anharmonic correction the adatom formation energy Ea is too low and similar to the surface
diffusion barrier. Instead, including the anharmonicity the estimate, Ea = (0.38 ± 0.03) eV, is in excellent agreement
with the predictions of molecular dynamics simulations
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