Peer-reviewed Publications |
Bobrov, K., Kalashnyk, N., & Guillemot, L. (2016). Thermodynamic balance of perylene self-assembly on Ag(110). J Chem Phys, 145(15), 154705.
Résumé: We present a room temperature STM study of perylene adsorption on Ag(110) at the monolayer coverage regime. We found that structure and symmetry of the perylene monolayer are settled by thermodynamic balance of the three factors: (i) the ability of perylene molecules to recognize specific adsorption sites on the (110) lattice, (ii) the intermolecular interaction, and (iii) the accommodation of thermal motion of the molecules. The moderate strength of the site recognition and the intermolecular interaction, of the same order of magnitude as kT approximately 25 meV, represents a key feature of the thermodynamic balance. It bestows to this system the unique quality to form the quasi-liquid monolayer of epitaxial as well as self-assembling character. The perylene monolayer accommodates the short-range motion of the molecules instead of quenching it. It precludes the formation of possible solid nuclei and maintains common registry of the included molecules. The surface registry of the quasi-liquid phase is provided by locking of a structure-related fraction of the perylene molecules into specific adsorption sites of the (110) lattice favorable in terms of intermolecular interaction.
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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.
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Dujardin, G., Boer-Duchemin, E., Le Moal, E., Mayne, A. J., & Riedel, D. (2016). DIET (Dynamics at surfaces Induced by Electronic Transitions) at the nanoscale. Surf. Sci., 643, 13–17.
Résumé: We review the long maturing evolution of DIET (Dynamics at surfaces Induced by Electronic Transitions) that began in the 1960s when Menzel, Gomer and Redhead proposed their famous stimulated desorption model. DIET entered the « nanoscale » in the 1990s when researchers at Bell Labs and IBM realized that the Scanning Tunneling Microscope (STM) could be used as an atomic size source of electrons to electronically excite individual atoms and molecules at surfaces. Resonant and radiant Inelastic Electron Tunneling (IET) using the STM have considerably enlarged the range of applications of DIET. Nowadays, « DIET at the nanoscale » covers a broad range of phenomena at the atomic-scale. This includes molecular dynamics (dissociation, desorption, isomerization, displacement, chemical reaction), vibrational spectroscopy and dynamics, spin spectroscopy and manipulation, luminescence spectroscopy, Raman spectroscopy and plasmonics. Future trends of DIET at the nanoscale offer exciting prospects for new methods to control light and matter at the nanoscale.
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Hamoudi, H., & Esaulov, V. A. (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.
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Jiang, T., Tong, Y., Bendounan, A., Nicolas, F., Kubsky, S., & Esaulov, V. A. (2016). Selenium and benzeneselenol interaction with Cu(111). RSC Adv., 6(88), 84627–84633.
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Kalashnyk N., Khemliche H., & Roncin P. (2016). Atom beam triangulation of organic layers at 100 meV normal energy:self-assembled perylene on Ag(1 1 0) at room temperature. Appl. Surf. Sci., 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.
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Rogez, B., Cao, S., Dujardin, G., Comtet, G., Le Moal, E., Mayne, A. J., & Boer-Duchemin, E. (2016). The mechanism of light emission from a scanning tunnelling microscope operating in air. Nanotechnology, 27(46), 465201.
Résumé: The scanning tunnelling microscope (STM) may be used as a low-energy, electrical nanosource of surface plasmon polaritons and light. In this article, we demonstrate that the optimum mode of operation of the STM for maximum photon emission is completely different in air than in vacuum. To this end, we investigate the emission of photons, the variation in the relative tip-sample distance and the measured current as a function of time for an STM operating in air. Contrary to the case of an STM operating in vacuum, the measured current between the tip and sample for an STM in air is very unstable (rapidly fluctuating in time) when the applied voltage between the tip and sample is in the ∼1.5–3 V range (i.e., in the energy range of visible photons). The photon emission occurs in short (50 μs) bursts when the STM tip is closest to the sample. The current instabilities are shown to be a key ingredient for producing intense light emission from an STM operating in air (photon emission rate several orders of magnitude higher than for stable current). These results are explained in terms of the interplay between the tunnel current and the electrochemical current in the ubiquitous thin water layer that exists when working in air.
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Sonnet, P., Stauffer, L., Gille, M., Bléger, D., Hecht, S., Cejas, C., Dujardin, G., & Mayne, A. J. (2016). Molecular dissociation on the SiC(0001)-3x3 surface. ChemPhysChem, 17(23), 3900–3906.
Résumé: In the framework of density functional theory, the adsorption of the halogenated polycyclic aromatic hydrocarbon 2,11-diiodohexabenzocoronene (HBC-I2) on the SiC(0001) 3×3 surface has been investigated. Nondissociative and dissociative molecular adsorption is considered, and simulated scanning tunneling microscopy (STM) images are compared with the corresponding experimental observations. Calculations show that dissociative adsorption is favorable and reveal the crucial importance of the extended flat carbon core on molecule–surface interactions in dissociative adsorption; the iodine atom–surface interaction is of minor importance. Indeed, removing iodine atoms does not significantly affect the STM images of the central part of the molecule. This study shows that the dissociation of large halogenated polycyclic aromatic hydrocarbon molecules can occur on the SiC surface. This opens up interesting perspectives in the chemical reactivity and functionalization of wide band gap semiconductors.
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Tong, Y., Jiang, T., Bendounan, A., Harish, M. N. K., Giglia, A., Kubsky, S., Sirotti, F., Pasquali, L., Sampath, S., & Esaulov, V. A. (2016). Case studies on the formation of chalcogenide self-assembled monolayers on surfaces and dissociative processes. Beilstein J Nanotechnol, 7, 263–277.
Résumé: This report examines the assembly of chalcogenide organic molecules on various surfaces, focusing on cases when chemisorption is accompanied by carbon-chalcogen atom-bond scission. In the case of alkane and benzyl chalcogenides, this induces formation of a chalcogenized interface layer. This process can occur during the initial stages of adsorption and then, after passivation of the surface, molecular adsorption can proceed. The characteristics of the chalcogenized interface layer can be significantly different from the metal layer and can affect various properties such as electron conduction. For chalcogenophenes, the carbon-chalcogen atom-bond breaking can lead to opening of the ring and adsorption of an alkene chalcogenide. Such a disruption of the pi-electron system affects charge transport along the chains. Awareness about these effects is of importance from the point of view of molecular electronics. We discuss some recent studies based on X-ray photoelectron spectroscopy that shed light on these aspects for a series of such organic molecules.
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Tong, Y., Jiang, T., Bendounan, A., Nicolas, F., Kubsky, S., & Esaulov, V. A. (2016). Selenium, Benzeneselenol, and Selenophene Interaction with Cu(100). J. Phys. Chem. C, 120(38), 21486–21495.
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Valdés, J. E., Vargas, P., & Esaulov, V. A. (2016). Energy losses of slow ions traveling through crystalline solids and scattered on crystalline surfaces. Radiation Effects and Defects in Solids, 171(1-2), 60–76.
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Xiao, X., Wenjun, W., Shuhong, L., Wanquan, Z., Dong, Z., Qianqian, D., Xuexi, G., & Bingyuan, Z. (2016). Investigation of defect modes with Al2O3 and TiO2 in one-dimensional photonic crystals. Optik – International Journal for Light and Electron Optics, 127(1), 135–138.
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Actes de Conférences |
Debiossac, M., & Roncin, P. (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
physical assumptions.
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Sereno, M., Lupone, S., Debiossac, M., Kalashnyk, N., & Roncin, P. (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.
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Chapitres de Livres |
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Oughaddou, H., Enriquez, H., Tchalala, M. R., Bendounan, A., Mayne, A. J., Sirotti, F., & & Dujardin, G. (2016). Silicene on Ag(111) and Au(110) surfaces. In Silicene; Structure, Properties and Applications (pp. 167–181). Springer Series in Materials Science, 235. Berlin: Spencer, M.J.S. & T. Morishita, T.
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