Peer-reviewed Publications |
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Alarcón, L. S., Jia, J., Carrera, A., Esaulov, V. A., Ascolani, H., Gayone, J. E., Sánchez, E. A., & Grizzi, O. (2014). Direct recoil spectroscopy of adsorbed atoms and self-assembled monolayers on Cu(001). Vacuum, 105, 80–87.
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Amiaud, L., Houplin, J., Bourdier, M., Humblot, V., Azria, R., Pradier, C. - M., & Lafosse, A. (2014). Low-energy electron induced resonant loss of aromaticity: consequences on cross-linking in terphenylthiol SAMs. PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 16(3), 1050–1059.
Résumé: Aromatic self-assembled monolayers (SAMs) can be used as negative tone electron resists in functional surface lithographic fabrication. A dense and resistant molecular network is obtained under electron irradiation through the formation of a cross-linked network. The elementary processes and possible mechanisms involved were investigated through the response of a model aromatic SAM, p-terphenylthiol SAM, to low-energy electron (0-10 eV) irradiation. Energy loss spectra as well as vibrational excitation functions were measured using High Resolution Electron Energy Loss Spectroscopy (HREELS). A resonant electron attachment process was identified around 6 eV through associated enhanced excitation probability of the CH stretching modes [small nu](CH)ph at 378 meV. Electron irradiation at 6 eV was observed to induce a peak around 367 meV in the energy loss spectra, attributed to the formation of sp3-hybridized CHx groups within the SAM. This partial loss of aromaticity is interpreted to be the result of resonance formation, which relaxes by reorganization and/or CH bond dissociation mechanisms followed by radical chain reactions. These processes may also account for cross-linking induced by electron irradiation of aromatic SAMs in general.
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Atkinson, P., Eddrief, M., Etgens, V. H., Khemliche, H., Debiossac, M., Momeni, A., Mulier, M., Lalmi, B., & Roncin, P. (2014). Dynamic grazing incidence fast atom diffraction during molecular beam epitaxial growth of GaAs. Appl. Phys. Lett., 105(2).
Résumé: A Grazing Incidence Fast Atom Diffraction (GIFAD) system has been mounted on a commercial molecular beam epitaxy chamber and used to monitor GaAs growth in real-time. In contrast to the conventionally used Reflection High Energy Electron Diffraction, all the GIFAD diffraction orders oscillate in phase, with the change in intensity related to diffuse scattering at step edges. We show that the scattered intensity integrated over the Laue circle is a robust method to monitor the periodic change in surface roughness during layer-by-layer growth, with oscillation phase and amplitude independent of incidence angle and crystal orientation. When there is a change in surface reconstruction at the start of growth, GIFAD intensity oscillations show that there is a corresponding delay in the onset of layer-by-layer growth. In addition, changes in the relative intensity of different diffraction orders have been observed during growth showing that GIFAD has the potential to provide insight into the preferential adatom attachment sites on the surface reconstruction during growth. (C) 2014 AIP Publishing LLC.
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Debiossac M. and Roncin P. (2014). Atomic diffraction under oblique incidence: An analytical expression. Phys. Rev. A., 90, 054701.
Résumé: The semiclassical perturbation method developed by Henkel et al. [J. Phys. II 4, 1955 (1994)] to model
cold-atom diffraction by optical standing waves, is applied to the diffraction of fast atoms on crystal surfaces at
grazing incidence (GIFAD or FAD).We first show that the interaction time and interaction length embedded in the
obliquity factor is well suited to explain the transition from three-dimensional to two-dimensional (2D) diffraction.
The situation of a slightly misaligned primary beam, corresponding to oblique incidence in the effective 2Dsystem,
is addressed pointing out discrepancies such as the absence of net deflection of the atomic beam. Guided by
time-reversal considerations, we propose an arbitrarily symmetrized form significantly improving the agreement
with experimental data recorded in oblique incidence.
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Debiossac, M., Zugarramurdi, A., Lunca-Popa, P., Momeni, A., Khemliche, H., Borisov, A. G., & Roncin, P. (2014). Transient Quantum Trapping of Fast Atoms at Surfaces. Phys. Rev. Lett., 112(2).
Résumé: We report on the experimental observation and theoretical study of the bound state resonances in fast atom diffraction at surfaces. In our studies, the He-4 atom beam has been scattered from a high-quality LiF(001) surface at very small grazing incidence angles. In this regime, the reciprocal lattice vector exchange with the surface allows transient trapping of the 0.3-0.5 keV projectiles into the quasistationary states bound by the attractive atom-surface potential well which is only 10 meV deep. Analysis of the linewidths of the calculated and measured resonances reveals that prior to their release, the trapped projectiles preserve their coherence over travel distances along the surface as large as 0.2 μm, while being in average only at some angstroms in front of the last atomic plane.
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Debiossac, M. and Z., A. and Khemliche, H. and Roncin, P. and Borisov, A. G. and Momeni, A. and Atkinson, P. and Eddrief, M. and Finocchi, F. and Etgens, V. H. (2014). Combined experimental and theoretical study of fast atom diffraction on the β2(2×4) reconstructed GaAs(001) surface. Phys. Rev. B, 90(15), 155308.
Résumé: A grazing incidence fast atom diffraction (GIFAD or FAD) setup, installed on a molecular beam epitaxy chamber, has been used to characterize the β2(2×4) reconstruction of a GaAs(001) surface at 530∘C under an As4 overpressure. Using a 400-eV 4He beam, high-resolution diffraction patterns with up to eighty well-resolved diffraction orders are observed simultaneously, providing a detailed fingerprint of the surface structure. Experimental diffraction data are in good agreement with results from quantum scattering calculations based on an ab initio projectile-surface interaction potential. Along with exact calculations, we show that a straightforward semiclassical analysis allows the features of the diffraction chart to be linked to the main characteristics of the surface reconstruction topography. Our results demonstrate that GIFAD is a technique suitable for measuring in situ the subtle details of complex surface reconstructions. We have performed measurements at very small incidence angles, where the kinetic energy of the projectile motion perpendicular to the surface can be reduced to less than 1 meV. This allowed the depth of the attractive van der Waals potential well to be estimated as −8.7 meV in very good agreement with results reported in literature.
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Hamoudi, H., Uosaki, K., Ariga, K., & Esaulov, V. A. (2014). Going beyond the self-assembled monolayer: metal intercalated dithiol multilayers and their conductance. RSC Adv., 4(75), 39657.
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Jia, J., Bendounan, A., Chaouchi, K., & Esaulov, V. A. (2014). Sulfur Interaction with Cu(100) and Cu(111) Surfaces: A Photoemission Study. J. Phys. Chem. C, , 24583–24590.
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Jia, J., Bendounan, A., Chaouchi, K., Kubsky, S., Sirotti, F., Pasquali, L., & Esaulov, V. A. (2014). Chalcogen Atom Interaction with Palladium and the Complex Molecule–Metal Interface in Thiol Self Assembly. J. Phys. Chem. C, 118(43), 24983–24994.
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Jia, J., Giglia, A., Flores, M., Grizzi, O., Pasquali, L., & Esaulov, V. A. (2014). 1,4-Benzenedimethanethiol Interaction with Au(110), Ag(111), Cu(100), and Cu(111) Surfaces: Self-Assembly and Dissociation Processes. J. Phys. Chem. C, 118(46), 26866–26876.
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Pasquali, L., Mukherjee, S., Terzi, F., Giglia, A., Mahne, N., Koshmak, K., Esaulov, V., Toccafondi, C., Canepa, M., & Nannarone, S. (2014). Structural and electronic properties of anisotropic ultrathin organic films from dichroic resonant soft x-ray reflectivity. Phys. Rev. B, 89(4), 045401.
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Piekarczyk, A., Bald, I., Flosadóttir, H. D., Ómarsson, B., Lafosse, A., & Ingólfsson, O. (2014). Influence of metal ion complexation on the metastable fragmentation of DNA hexamers. Eur. Phys. J. D, 68(6), 146.
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Actes de Conférences |
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Chen, L., & Esaulov, V. A. (2014). Energy loss of keV ions in grazing scattering on gold surfaces. In JOURNAL OF PHYSICS-CONFERENCE SERIES (Vol. 488, 132016).
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