lundi 24 avril
Mise à jour
mercredi 19 avril
Debiossac, M., Zugarramurdi, A., Mu, Z., Lunca-Popa, P., Mayne, A. J., & Roncin, P. (2016). Helium diffraction on SiC grown graphene: Qualitative and quantitative descriptions with the hard-corrugated-wall model. PHYSICAL REVIEW B, 94(20), 205403.
Résumé: Monolayer epitaxial graphene grown on 6H-SiC(0001) was recently investigated by grazing-incidence fastatom diffraction and analyzed with an ab initio electronic density calculation and with exact atomic diffraction methods. With these results as a reference, the hard-corrugated-wall model (HCW) is used as a complementary analytic approach to link binary potentials to the observed atomic corrugation. The main result is that the HCW model reproduces the macroscopic corrugation of the moir´e pattern on a quantitative level, suggesting that soft-wall corrections may be neglected for macroscopic superstructures, allowing straightforward analysis in terms of a one-dimensional corrugation function.
H.Hamoudi, & V.A.Esaulov. (2016). Selfassembly of α,ω-dithiols on surfaces and metal dithiol heterostructures. Ann.Phys, , 1–22.
Résumé: α,ω-Dithiols present an interesting case of molecules with
two reactive terminal -SH groups (HS-R-SH) that allow their
use as binders between different metallic entities. They have
thus been used in molecular electronics conduction measurements,
in “nanogap” electrodes of interest in plasmonics,
as building blocks of more complex structures such as
metal intercalated superlattices and in the formation of
metalized organic thin films, including doped graphene
type films. There exist however many problems, because
the molecules may end up in undesirable configurations
with both thiol terminals bound to the same metal particle/
substrate or link with other molecules to produce
“multi-molecule” or “multilayer” structures. This report discusses
various key questions on dithiol linking with metal
surfaces and the quest of protocols of making problem free
dithiol metal structures. It then describes the use of dithiols
and their SAMs to produce various metal organic heterostructures
useful for molecular electronics and formation
of doped metalized organic thin films. We discuss the
build up of these structures by self assembly and lithography,
their chemical composition and functional properties.
Nataliya Kalashnyk, H. K., Philippe Roncin. (2016). Atom beam triangulation of organic layers at 100 meV normal energy:self-assembled perylene on Ag(1 1 0) at room temperature. Applied Surface Science, 364, 235–240.
Résumé: The controlled growth of organic layers on surfaces is still waiting for an in-situ reliable technique thatwould allow their quality to be monitored and improved. Here we show that the growth of a perylene monolayer deposited on Ag(110) at room temperature can be tracked with low energy atoms in a regime where the energy perpendicular to the layer is less than 0.1 eV and below the organic film damage threshold. The image processing required for this atom triangulation technique is described in detail.
Actes de Conférences
M. Debiossac, P. A., A. Zugarramurdi, M. Eddrief, F. Finocchi, V.H. Etgens, A. Momeni, H. Khemliche, A.G. Borisov, P. Roncin. (2016). Fast atom diffraction inside a molecular beam epitaxy chamber, a rich combination. In APPLIED SURFACE SCIENCE.
Résumé: Two aspects of the contribution of grazing incidence fast atom diffraction (GIFAD) to molecular beam epitaxy (MBE) are reviewed here: the ability of GIFAD to provide in-situ a precise description of the atomic-scale surface topology, and its ability to follow larger-scale changes in surface roughness during layer-by-layer growth. Recent experimental and theoretical results obtained for the He atom beam incident along the highly corrugated View the MathML source[11¯0] direction of the β2(2 × 4) reconstructed GaAs(001) surface are summarized. We also discuss the measurements and calculations for the beam incidence along the weakly corrugated  direction where a periodicity twice smaller than expected is observed. The combination of the experiment, quantum scattering matrix calculations, and semiclassical analysis allows structural characteristics of the surface to be revealed. For the in situ measurements of GIFAD during molecular beam epitaxy of GaAs on GaAs surface we analyze the change in elastic and inelastic contributions in the scattered beam, and the variation of the diffraction pattern in polar angle scattering. This analysis outlines the robustness, the simplicity and the richness of the GIFAD as a technique to monitor the layer-by-layer epitaxial growth
M. Sereno, S. L., M. Debiossac, N. Kalashnyk, P. Roncin. (2016). Active correction of the tilt angle of the surface plane with respect to the rotation axis during azimuthal scan. In NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS (Vol. 382, 123).
Résumé: A procedure to measure the residual tilt angle ττ between a flat surface and the azimuthal rotation axis of the sample holder is described. When the incidence angle θ and readout of the azimuthal angle ϕ are controlled by motors, an active compensation mechanism can be implemented to reduce the effect of the tilt angle during azimuthal motion. After this correction, the effective angle of incidence is kept fixed, and only a small residual oscillation of the scattering plane remains.
Maxime Debiossac, P. R. (2016). Image processing for grazing incidence fast atom diffraction. In NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS (Vol. 382, 36).
Résumé: Grazing incidence fast atom diffraction (GIFAD, or FAD) has developed as a surface sensitive technique.
Compared with thermal energies helium diffraction (TEAS or HAS), GIFAD is less sensitive to thermal
decoherence but also more demanding in terms of surface coherence, the mean distance between defects.
Such high quality surfaces can be obtained from freshly cleaved crystals or in a molecular beam epitaxy
(MBE) chamber where a GIFAD setup has been installed allowing in situ operation. Based on recent pub-
lications by Atkinson et al. (2014) and Debiossac et al. (2014), the paper describes in detail the basic steps
needed to measure the relative intensities of the diffraction spots. Care is taken to outline the underlying