Peer-reviewed Publications |
Abouaf, R., & Teillet-Billy, D. (2008). Low energy electron collisions in H2S and H2Se: Structure in dissociative attachment cross-sections. INTERNATIONAL JOURNAL OF MASS SPECTROMETRY, 277(1-3), 79–83.
Résumé: Dissociative electron attachment between 0 and 4 eV has been investigated in hydrogen sulfide and hydrogen selenide with an improved electron resolution (0.040 eV). HS- and HSe- cross-sections versus electron energy present vertical onsets revealing that the potential surfaces of the resonances which are reached around 2 eV are bound. A well-developed and intriguing structure is observed in HS-, S-, HSe- and Se- cross-sections. It could reveal interferences due to an attractive resonance having a lifetime of the order of one vibrational period. The strong similarity between the anion behaviour in H2S and H2Se is in contrast with H2O where no dissociative attachment process occurs in this energy range. (C) 2008 Elsevier B.V. All rights reserved.
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Abouaf, R., Ptasinska, S., & Teillet-Billy, D. (2008). Low energy electron impact on gas phase 5-nitrouracil. CHEMICAL PHYSICS LETTERS, 455(4-6), 169–173.
Résumé: Excitation of the first electronic states, vibrational excitation between 1 and 3 eV, and negative ion formation (0-2 eV) in gas phase 5-nitrouracil are presented. Five singlet states are clearly identified at 4.76; 5.72; 6.82; 7.82 and 9.2 eV. A band at 3.7 eV could be assigned to a triplet state. The vibrational modes observed indicate resonant states having both pi* and sigma* character. The most intense anions (M-NO2) , (M-H) appear at zero energy with huge cross sections (>= 10 18 m(2)). Anion cross sections versus electron energy reveal structures interpreted using the anion energy thresholds found by DFT calculations. (C) 2008 Elsevier B.V. All rights reserved.
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Amiaud, L., Momeni, A., Dulieu, F., Fillion, J. H., Matar, E., & Lemaire, J. L. (2008). Measurement of the adsorption energy difference between ortho- and para-D(2) on an amorphous ice surface. Phys. Rev. Lett., 100(5), 056101.
Résumé: Molecular hydrogen interaction on water ice surfaces is a major process taking place in interstellar dense clouds. By coupling laser detection and classical thermal desorption spectroscopy, it is possible to study the effect of rotation of D(2) on adsorption on amorphous solid water ice surfaces. The desorption profiles of ortho- and para-D(2) are different. This difference is due to a shift in the adsorption energy distribution of the two lowest rotational states. Molecules in J('')=1 rotational state are on average more strongly bound to the ice surface than those in J('')=0 rotational state. This energy difference is estimated to be 1.4 +/- 0.3 meV. This value is in agreement with previous calculation and interpretation. The nonspherical wave function J('')=1 has an interaction with the asymmetric part of the adsorption potential and contributes positively in the binding energy.
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Atabek, O., & Lefebvre, R. (2008). Multiple occurrence of zero-width resonances in photodissociation: Effect of laser field intensity and frequency. PHYSICAL REVIEW A, 78(4), 043419.
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Baffou, G., Mayne, A. J., Comtet, G., & Dujardin, G. (2008). State selective electron transport through electronic surface states of 6H-SiC(0001)-3 x 3. Phys. Rev. B, 77(16), 165320.
Résumé: We investigate charge transport through electronic surface states of the 6H-SiC(0001)-3 x 3 surface. Three intrinsic surface states are located within the wide bulk band gap, in which two (S(1) and U(1)) arise from strongly correlated electronic states and the third (S(2)) has negligible electron correlation effects. Combined conductance and luminescence experiments with the scanning tunneling microscope show that the Mott-Hubbard surface states (S(1) and U(1)) have a high resistance (1.0 G Omega), while the noncorrelated state (S(2)) has a negligible resistance. Consequently, current can be selectively transported through any of these three surface states.
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Basire, M., Parneix, P., & Calvo, F. (2008). Quantum anharmonic densities of states using the Wang-Landau method. JOURNAL OF CHEMICAL PHYSICS, 129(8).
Résumé: The Wang-Landau sampling method is adapted to the calculation of quantum densities of states for fully coupled anharmonic systems. The accuracy of the method is illustrated against exact counting for two molecules with separable oscillators, namely, the Zundel complex H(5)O(2)(+) and the Na(11) cluster. Application to the fully coupled naphthalene molecule (C(10)H(8)) reveals significant deviations in the finite temperature thermodynamical properties that are not captured by simple perturbation theory. There are no limitations in the size of the molecules that can be treated with this method. (c) 2008 American Institute of Physics.
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Bellec, A., Riedel, D., Dujardin, G., Rompotis, N., & Kantorovich, L. N. (2008). Dihydride dimer structures on the Si(100):H surface studied by low-temperature scanning tunneling microscopy. Phys. Rev. B, 78(16), 165302.
Résumé: Surface reconstructions on the hydrogenated Si(100):H surface are observed and investigated by using a low-temperature (5 K) scanning tunneling microscope (STM). In addition to the well established 2x1 and 3x1 phases, linear structures extending over one to six silicon dimers along the same dimer row are observed. After a careful analysis of the corresponding STM topographies for both n-type and p-type doped silicon substrates, we conclude that these structures are dihydride dimers. This assignment is supported by ab initio density-functional calculations of the local density of states of dihydride structures of one or two dimers long. Furthermore, the calculation of the free-energy formation of our observed structure shows that their creation is closely linked with the hydrogenation process. These results demonstrate that the previous assignments of “split dimer” and “bow-tie” structures to dihydride dimers and dopant pairs, respectively, need to be reconsidered.
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Bergeron, H., Rougeau, N., Sidis, V., Sizun, M., Teillet-Billy, D., & Aguillon, F. (2008). OH Formation from O and H Atoms Physisorbed on a Graphitic Surface through the Langmuir-Hinshelwood Mechanism: A Quasi-Classical Approach. J. Phys. Chem. A, 112(46), 11921–11930.
Résumé: We study the quasi-classical dynamics of OH formation on a graphitic surface through the Langmuir-Hinshelwood (LH) mechanism when both 0 and H ground-state atoms are initially physisorbed on the surface. The model proceeds from previous theoretical work on the LH formation of the H-2 molecule on graphite [Morisset, S.; Aguillon, F.; Sizun, M.; Sidis, V. J. Chem. Phys. 2004, 121, 6493; ibid 2005, 122, 194704]. The H-graphite system is first revisited with a view to get a tractable DFT-GGA computational prescription for the determination of atom physisorption onto graphitic surfaces. The DZP-RPBE combination is found to perform well; it is thereafter used along with MP2 calculations to determine the physisorption characteristics of atomic oxygen on graphitic surfaces. We also deal with chemisorption. In accordance with previous work, we find that 0 chemisorbs on graphite in a singlet spin state epoxy-like conformation. In the triplet state we find only “metastable” chemisorption with an activation barrier of 0.2 eV. The physisorption results are then used in the LH dynamics calculation. We show that in the [0.15 meV, 12 meV] relative collision energy range of the reacting 0 and H atoms on the surface, the OH molecule is produced with a large amount of internal energy (similar or equal to 4 eV) and a significant translation energy (>= 100 meV) relative to the surface.
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Blandin, P., Druon, F., Hanna, M., Leveque-Fort, S., Lesvigne, C., Couderc, V., Leproux, P., Tonello, A., & Georges, P. (2008). Picosecond polarized supercontinuum generation controlled by intermodal four-wave mixing for fluorescence lifetime imaging microscopy. OPTICS EXPRESS, 16(23), 18844–18849.
Résumé: We present the generation of a picosecond polarized supercontinuum in highly birefringent multimodal microstructured fiber. The initial steps of the spectral broadening are dominated by intermodal four-wave mixing controlled by the specific fiber design. Using a low repetition rate ultra-stable solid state laser, a pulse train well-suited for versatile time-domain fluorescence lifetime imaging applications is obtained. (C) 2008 Optical Society of America
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Bobrov, K., & Guillemot, L. (2008). Interplay between adsorbate-induced reconstruction and local strain: Formation of phases on the Cu(110)-(2x1): O surface. PHYSICAL REVIEW B, 78(12), 121408.
Résumé: We present an STM study on the interplay between adsorbate-induced reconstruction and local strain on the oxygen adsorbed Cu(110) surface. Thermal annealing of the surface resulted in surface terrace ripening revealing larger terraces, uniformly covered by the (2x1)-O reconstructed phase, separated by step bunches. The largest terrace was found to be partially splitted by emerging dislocations inducing strong inhomogeneous strain in their close vicinity. This extra strain caused local conversion of the dominating (2x1)-O phase into oxygen chemisorbed phases drastically different from the dominating phase. A meaningful correlation between lateral evolution of the extra strain and structure of these phases has been found. The symmetry of the discovered phases has been determined and their structural models have been elaborated.
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Bojarska, E., Kazimierczuk, Z., Mouchard, C., Tfibel, F., & Fontaine-Aupart, M. - P. (2008). UVC induced oxidation of chloropurines: excited singlet and triplet pathways for the photoreaction. PHOTOCHEMICAL & PHOTOBIOLOGICAL SCIENCES, 7(9), 1054–1062.
Résumé: The phototransformation of 2-chloro. 6-chloro and 2,6-dichloropurines under UVC excitation (254 nm) has been studied and the major photoproducts have been identified using absorption spectroscopy, HPLC and mass spectrometry It was shown that hydropurines were formed as the main products for all three investigated compounds both in the presence and absence of oxygen. In the case of 6-chloro- and 2,6-dichloropurine, a photodimer is also formed as a minor photoproduct in the absence of oxygen but is efficiently quenched in the presence of oxygen. Nanosecond photolysis experiments also revealed significant intersystem crossing to the triplet state of the chloropurines which has been characterized (transient absorption spectra, triplet formation quantum yields and rate constants of quenching by oxygen, Mn2+ ions and ground state). Experimental evidence allows to Conclude that the triplet state is involved in photodimer formation whereas the hydroxypurine is formed from the reaction of the excited singlet state of chloropurines with the solvent (water addition) through heterolytic C-Cl bond rupture. Mass spectrometry and H-1 NMR results allowed to propose a chemical pathway for dimer formation in the case of 2,6-dichloropurine in a two-step process: first a homolytic rupture of C-Cl bond in the triplet state of the molecule with the formation of purinyl radicals, which subsequently react with an excess of ground state molecules and/or hydroxypurine primarily formed.
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Borisov, A. G., Sametoglu, V., Winkelmann, A., Kubo, A., Pontius, N., Zhao, J., Silkin, V. M., Gauyacq, J. P., Chulkov, E. V., Echenique, P. M., & Petek, H. (2008). Pi resonance of chemisorbed alkali atoms on noble metals. Phys. Rev. Lett., 101(26), 266801.
Résumé: We have performed a joint experimental and theoretical study of the unoccupied electronic structure of alkali adsorbates on the (111) surfaces of Cu and Ag. Combining angle- and time-resolved two-photon photoemission spectroscopy with wave packet propagation calculations we show that, along with the well known sigma resonance oriented along the surface normal, there exist long-lived alkali-localized resonances oriented parallel to the surface (pi symmetry). These new resonances are stabilized by the projected band gap of the substrate and emerge primarily from the mixing of the p and d Rydberg orbitals of the free alkali atom modified by the interaction with the surface.
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Boye-Peronne, S., & Gauyacq, D. (2008). Photolysis of small hydrocarbons: a source of radicals for the carbon chemistry in space. ACTUALITE CHIMIQUE, (315), X-XV.
Résumé: The carbon chemistry in the interstellar and cometary media is driven by reaction chains initiated by small radicals such as C-2, C2H, or CH. For many years, the different photochemical steps involved in the production of these reactive radicals were not clearly identified. The role of the stable hydrocarbon molecules (acetylene, ethylene, etc.) as mother molecules is no longer subject of debate. This paper illustrates a spectroscopic method aimed to characterise the radical products and to measure their abundance from an irradiation close to the vacuum-ultraviolet flux present in comets or near carbon-rich stars. Experiments performed with a synchrotron radiation source enable to detail the nature of the primary reactions occurring in the gas phase and involving small hydrocarbon mother molecules. The photolysis of acetylene C2H2 and ethylene C2H4 will be shown as an example of this laboratory-based approach.
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Briandet, R., Lacroix-Gueu, P., Renault, M., Lecart, S., Meylheuc, T., Bidnenko, E., Steenkeste, K., Bellon-Fontaine, M. - N., & Fontaine-Aupart, M. - P. (2008). Fluorescence correlation spectroscopy to study diffusion and reaction of bacteriophages inside biofilms. APPLIED AND ENVIRONMENTAL MICROBIOLOGY, 74(7), 2135–2143.
Résumé: In the natural environment, most of the phages that target bacteria are thought to exist in biofilm ecosystems. The purpose of this study was to gain a clearer understanding of the reactivity of these viral particles when they come into contact with bacteria embedded in biofilms. Experimentally, we quantified lactococcal c2 phage diffusion and reaction through model biofilms using in situ fluorescence correlation spectroscopy with two-photon excitation. Correlation curves for fluorescently labeled c2 phage in nonreacting Stenotrophomonas maltophilia biofilms indicated that extracellular polymeric substances did not provide significant resistance to phage penetration and diffusion, even though penetration and diffusion were sometimes restricted because of the noncontractile tail of the viral particle. Fluctuations in the fluorescence intensity of the labeled phage were detected throughout the thickness of biofilms formed by c2-sensitive and c2-resistant strains of Lactococcus lactis but could never be correlated with time, revealing that the phage was immobile. This finding confirmed that recognition binding receptors for the viral particles were present on the resistant bacterial cell wall. Taken together, our results suggest that biofilms may act as “active” phage reservoirs that can entrap and amplify viral particles and protect them from harsh environments.
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Bundaleski, N., Khemliche, H., Soulisse, P., & Roncin, P. (2008). Grazing incidence diffraction of keV helium atoms on a Ag(110) surface. Phys. Rev. Lett., 101(17), 177601.
Résumé: Diffraction of fast atoms at grazing incidence has been recently demonstrated on the surface of alkali halides and wide band gap semiconductors, opening applications for the online monitoring of surface processes such as growth of ultrathin layers. This Letter reports energy resolved diffraction of helium on Ag(110) metal surface showing that a band gap is not mandatory to restrict the decoherence due to electron-hole pair excitations by the keV projectile. Measurement of the energy loss, which is in the eV range, sheds light on the scattering process.
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Burean, E., Abouaf, R., Lafosse, A., Azria, R., & Swiderek, P. (2008). High-resolution vibrational electron-energy-loss spectroscopy of gaseous and solid glycine. JOURNAL OF PHYSICAL CHEMISTRY C, 112(25), 9405–9411.
Résumé: The vibrational spectra of thin solid films of glycine deposited at temperatures between 12 and 130 K, as well as gaseous glycine, have been measured by high-resolution electron-energy-loss (HREEL) spectroscopy. The spectra are dominated by hydrogen-bonded glycine dimers when the films are deposited at low temperatures. The HREEL spectra of films deposited at higher temperature (130 K) have a different habitus that can be explained on the basis of a proton transfer reaction leading to the formation of zwitterionic glycine. Gas-phase HREEL spectra show bands characteristic of the neutral monomer of glycine. The results are discussed in relation to a previous study aiming at glycine synthesis in mixed ices under the effect of low-energy electrons.
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Casagrande, E. M. S., Naja, A., Mezdari, F., Lahmam-Bennani, A., Bolognesi, P., Joulakian, B., Chuluunbaatar, O., Al-Hagan, O., Madison, D. H., Fursa, D. V., & Bray, I. (2008). (e,2e) ionization of helium and the hydrogen molecule: signature of two-centre interference effects. JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS, 41(2).
Résumé: Relative (e,2e) triply differential cross sections (TDCS) are measured for the ionization of the helium atom and the hydrogen molecule in coplanar asymmetric geometry at a scattered electron energy of 500 eV and ejected electron energies of 205, 74 and 37 eV. The He experimental results are found to be in very good agreement with convergent close-coupling calculations (CCC). The H(2) experimental results are compared with two state-of-the-art available theoretical models for treating differential electron impact ionization of molecules. Both models yield an overall good agreement with experiments, except for some intensity deviations in the recoil region. Similar (e, 2e) works were recently published on H(2) with contrasted conclusions to the hypothesis that the two H nuclei could give rise to an interference pattern in the TDCS structure. Murray (2005 J. Phys. B: At. Mol. Opt. Phys. 38 1999) found no evidence for such an effect, whereas Milne-Brownlie et al (2006 Phys. Rev. Lett. 96 233201) reported its indirect observation. In this work, based on a direct comparison between experimental results for He and H(2), we observe an oscillatory pattern due to these interference effects, and for the first time the destructive or constructive character of the interference is observed, depending on the de Broglie wavelength of the ejected electron wave. The experimental finding is in good agreement with the theoretical prediction by Stia et al (2003 J. Phys. B: At. Mol. Opt. Phys. 36 L257).
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Charron, E., Milman, P., Keller, A., & Atabek, O. (2008). Erratum: Quantum phase gate and controlled entanglement with polar molecules [Phys. Rev. A 75, 033414 (2007)]. PHYSICAL REVIEW A, 77(3), 039907.
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Colgan, J., Huetz, A., Reddish, T. J., & Pindzola, M. S. (2008). Internuclear separation dependence of the angular distributions from photoionization of H(2)(+). JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS, 41(8).
Résumé: Recent experimental and theoretical works examining the double photoionization of H(2) have uncovered surprising changes in the resulting fully differential cross sections as the kinetic energy released to the outgoing protons is varied. In this work, a complementary study is made of the angular distributions arising from the photoionization of H(2)(+) at various internuclear separations R. Different internuclear separations correspond to different amounts of kinetic energy released to the exploding protons. We find that the angular distributions for the sigma(g) --> pi(u) transition in H(2)(+) are relatively insensitive to changes in R, but that the angular distributions for the sigma(g) --> pi(u) transition display dramatic variations with R. We investigate the underlying mechanisms of these phenomena, and explore the implications of these findings for the double photoionization of H(2).
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Crepin, C., Moneron, L., Douin, S., Boye-Peronne, S., Kolos, R., Turowski, M., Gronowski, M., Sepiol, J., Benilan, Y., & Gazeau, M. - C. (2008). Tentative identification of C3N center dot radical luminescence in solid krypton. POLISH JOURNAL OF CHEMISTRY, 82(4), 741–749.
Résumé: A product of cyanoacetylene photodissociation in Kr matrices gives rise to visible emis-. sion bands tentatively identified as due to the fluorescence and to the phosphorescence of the C3N center dot radical. This assignment, which involves the low-lying (A) over tilde (2) Pi state as the final one for both emissions, is based on the isotopic substitution study and on former theoretical predictions.
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Cuisset, A., Mouret, G., Pirali, O., Roy, P., Cazier, F., Nouali, H., & Demaison, J. (2008). Gas-phase vibrational spectroscopy and ab initio study of organophosphorous compounds: Discrimination between species and conformers. JOURNAL OF PHYSICAL CHEMISTRY B, 112(39), 12516–12525.
Résumé: Gas phase vibrational spectra of dimethyl methylphosphonate (DMMP), trimethyl phosphate (TMP), and triethyl phosphate (TEP) have been measured using FTIR spectroscopy. For DMMP, TMP, and TEP, most of the infrared active vibrational modes have been observed in the 50-5000 cm(-1) spectral range, allowing an unambiguous discrimination between the three molecules. The vibrational analysis of the spectra was performed by comparing with MP2 and B3LYP harmonic and anharmonic force field ab initio calculations. The extension to anharmonic calculations provides the best agreement for the mid-infrared and the near-infrared spectra, but they do not improve the harmonic frequency predictions in the far-infrared domain. This part of the vibrational spectra associated with collective and nonlocalized vibrational modes presents the largest frequency differences between the two lowest energy conformers of DMMP and TMP. These two conformers were taken into account in the vibrational assignment of the spectra. Their experimental evidence was obtained by deconvoluting vibrational bands in the mid-infrared and in the far-infrared regions, respectively. For TEP, the conformational landscape appears very complicated at ambient temperature, and a further analysis at low temperature is required to explain the vibrational features of each conformer.
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Dablemont, C., Lang, P., Mangeney, C., Piquemal, J. Y., Petkov, V., Herbst, F., & Viau, G. (2008). FTIR and XPS study of Pt nanoparticle functionalization and interaction with alumina. LANGMUIR, 24(11), 5832–5841.
Résumé: Platinum nanoparticles with a mean size of 1.7 nm were synthesized by reduction in sodium acetate solution in 1,2-ethanediol. The particles were then functionalized with dodecylamine, dodecanethiol, and omega-mercapto-undecanoic acid (MUDA). Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) showed important variations of the particle surface state with functionalization whereas their structure differs only slightly. Platinum-to-sulfur charge transfer inferred front XPS of thiol-coated particles enabled the identification of the formation of Pt delta+-S delta- bonds. The native carbon monoxide (CO) at the surface of the particles was a very efficient probe for following the functionalization of the particles by FTIR. The red shift of nu(CO) accounts for the nature of the ligands at the surface of the particles and also for their degree of functionalization. Immobilization on alumina substrates of particles functionalized with MUDA was realized by immersion in colloidal solutions. Free molecules, isolated particles, and aggregates of particles interconnected by hydrogen bonds at the surface of alumina were evidenced by FTIR. With successive washings, the energy variation of the CO stretch of carbon monoxide and of carboxylic acid groups and the relative intensity nu(CH2)/nu(CO) showed that the free molecules are eliminated first, followed by aggregates and less-functionalized particles. Particles presenting a high degree of functionalization by MUDA remain and interact strongly with alumina.
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De Padova, P., Leandri, C., Vizzini, S., Quaresima, C., Perfetti, P., Olivieri, B., Oughaddou, H., Aufray, B., & Le Lay, G. (2008). Burning match oxidation process of silicon nanowires screened at the atomic scale. NANO LETTERS, 8(8), 2299–2304.
Résumé: Silicon oxide nanowires hold great promise for functional nanoscale electronics. Here, we investigate the oxidation of straight, massively parallel, metallic Si nanowires. We show that the oxidation process starts at the Si NW terminations and develops like a burning match. While the spectroscopic signatures on the virgin, metallic part, are unaltered we identify four new oxidation states on the oxidized part, which show a gap opening, thus revealing the formation of a transverse internal nanojunction.
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Diaz-Tendero, S., Foelsch, S., Olsson, F. E., Borisov, A. G., & Gauyacq, J. - P. (2008). Electron propagation along Cu nanowires supported on a Cu(111) surface. Nano Lett., 8(9), 2712–2717.
Résumé: We present a joint experimental-theoretical study of the one-dimensional band of excited electronic states with sp character localized on Cu nanowires supported on a Cu(111) surface. Energy dispersion and lifetime of these states have been obtained, allowing the determination of the mean distance traveled by an excited electron along the nanowire before it escapes into the substrate. We show that a Cu nanowire supported on a Cu(111) surface can guide a one-dimensional electron flux over a short distance and thus can be considered as a possible component for nanoelectronics devices.
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Diaz-Tendero, S., Olsson, F. E., Borisov, A. G., & Gauyacq, J. - P. (2008). Theoretical study of electron confinement in Cu corrals on a Cu(111) surface. Phys. Rev. B, 77(20), 205403.
Résumé: We present a theoretical study of the energies, lifetimes, wave functions, and decay paths of the excited electronic states in corral structures formed by Cu adatoms on the Cu(111) surface. Three different corrals with 35, 48, and 70 Cu adatoms have been studied within a joint approach including the density functional theory and wave packet propagation. Confinement of the electronic surface state inside the corral structure leads to the formation of well-defined resonances in the density of electronic states. Particular emphasis is given in the present work to the role of excited electronic states localized on the ring of Cu adatoms forming the corral. While never discussed in the past for corral structures, these states are equivalent to the one-dimensional sp band of Cu atomic chains assembled on the Cu(111) surface that has been recently studied thoroughly. The coupling between the confined surface state resonances and the sp state localized on the Cu ring have been studied in detail. It is shown that the sp state localized on the corral wall appears as a strong perturbation in the spectrum of confined states.
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Dozova, N., Murray, C., McCaffrey, J. G., Shafizadeh, N., & Crepin, C. (2008). Amplified emission of phthalocyanine isolated in cryogenic matrices. PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 10(16), 2167–2174.
Résumé: Laser induced fluorescence spectroscopy of free-base (H2Pc) and zinc (ZnPc) phthalocyanines trapped in rare gas and nitrogen matrices reveals a quite unexpected phenomenon with a moderate increase in the laser intensity. In all matrices except Xe, a huge increase occurs in the intensity of an emission band near 755 nm when pumping the S-1 <- S-0 transition. The band involves a vibrational mode of the ground state, located at 1550 and 1525 cm(-1) for H2Pc and ZnPc, respectively. Many of the characteristics of amplified emission (AE) are exhibited by this vibronic transition. Excitation scans recorded for the AE band yield greatly enhanced site selectivity compared to what is obtained in normalfluorescence excitation scans.
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Falvo, C., Hayashi, T., Zhuang, W., & Mukamel, S. (2008). Coherent two dimensional infrared spectroscopy of a cyclic decapeptide Antamanide. A simulation study of the amide-I and A bands. JOURNAL OF PHYSICAL CHEMISTRY B, 112(39), 12479–12490.
Résumé: The two-dimensional infrared photon echo spectrum of Antamanide (-(1)Val-(2)Pro-(3)Pro-(4)Ala-(5)Phe-(6)Phe-(7)Pro-(8)Pro-(9)Phe-(10)Pro -) in chloroform is calculated using an explicit solvent molecular dynamics (MD) simulation combined with a density functional theory (DFT) map for the effective vibrational Hamiltonian. Evidence for a strong intramolecular hydrogen bonding network is found. Comparison with experimental absorption allows the identification of the dominant conformation. Multidimensional spectroscopy reveals intramolecular couplings and gives information on its dynamics. A two-color amide-I and amide-A crosspeak is predicted and analyzed in terms of local structure.
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Ferro, Y., Teillet-Billy, D., Rougeau, N., Sidis, V., Morisset, S., & Allouche, A. (2008). Stability and magnetism of hydrogen dimers on graphene. PHYSICAL REVIEW B, 78(8), 085417.
Résumé: We report on the magnetism and stability of H dimers on a graphene sheet. Graphene is used as a simple model to grasp the basics of the H interaction with graphitic systems including graphite, graphene, polyaromatic hydrocarbons, and nanotubes. The dimers investigated here are found to be in ferromagnetic, antiferromagnetic, or nonmagnetic states. Results obtained from DFT calculations on the H dimer adsorption are analyzed with the help of spin-density maps. We thereby show that the dimer stability results from the magnetic properties of the pair of H atoms on graphene. The stability of dimers adsorbed in ortho and para positions is particularly emphasized. In order to rationalize the single and double H atom adsorption mechanisms, the whole pair formation process is divided into theoretical elementary steps to which energetic values are assigned.
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Gauyacq, J. P. (2008). Laser-induced photo-desorption in the Na/Cu(111) system. SURFACE SCIENCE, 602(22), 3477–3483.
Résumé: Desorption in the Na/Cu(111) system induced by an electronic excitation is studied using a quantal approach. The system is excited by a laser pulse in the fs range to the Na state corresponding to the transient capture of an electron by the alkali adsorbate. The present quantal approach describes on an equal footing the laser-induced vibrational excitation of the adsorbate in the adsorption well and the photo-desorption process. It confirms earlier results using a semi-classical input. It also allows a discussion of the photo-desorption probability with the photon energy: the maximum of the desorption probability per absorbed photon occurs off-resonance in the high-energy wing of the electronic transition. This feature is related to the dynamics of the laser-induced process. (C) 2008 Elsevier B.V. All rights reserved.
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Guillemot, L., Bandurin, Y., Bobrov, K., & Esaulov, V. A. (2008). Electron transfer processes between sputtered O atoms and Ag(110): O(n x 1) reconstructed surfaces. JOURNAL OF PHYSICS-CONDENSED MATTER, 20(35).
Résumé: We present results of a study of sputtered oxygen atom outgoing trajectory dependence of the electron transfers with oxidized Ag(110) surfaces reconstructed in different (n x 1) added row structures. With a charge state resolved time-of-flight-direct recoil spectroscopy investigation using 4 keV Ar(+) incident ions, we determine relative yields of sputtered O and Ag atoms as well as the fraction of sputtered O-ions, for different incident polar and azimuthal angles. The relative yields of sputtered O atoms are satisfactorily reproduced by a classical dynamics simulation. No sputtered Ag-ions were detected. A qualitative discussion of the features of the oxygen negative ion fractions suggests that its description needs, in general, to take into account both capture and loss of electrons as the oxygen atom leaves the surface. The experimental data also suggest that one needs to correctly describe the corrugation of the surface and that the electron loss rates should be site-specific.
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Guo, Z., Zheng, W., Hamoudi, H., Dablemont, C., Esaulov, V. A., & Bourguignon, B. (2008). On the chain length dependence of CH3 vibrational mode relative intensities in sum frequency generation spectra of self assembled alkanethiols. SURFACE SCIENCE, 602(23), 3551–3559.
Résumé: A global modelling of Sum Frequency Generation (SFG) spectra of the self assembly of alkanethiols is presented. All CH modes are modelled together. CH2 modes are assumed local to allow easy calculation of the spectrum as a function of molecular conformation. Ab initio molecular hyperpolarizabilities are used. A phenomenological approach is used to include the Fermi resonance in the model: the calculated intensity of the CH3 symmetric stretch is redistributed according to intensity borrowing by the Fermi resonance. The model is applied to octadecanethiol (ODT) and pentadecanethiol (PDT). The even/odd intensity alternation of SFG CH3 vibrational bands as a function of chainlength is used to test the model. It is found that the relative magnitudes of the hyperpolarizability tensors of the CH3 asymmetric and symmetric modes need to be adjusted. The model provides tilt and twist angles of the alkyl chain in agreement with the literature. It shows that the all trans conformation does not imply the absence of CH2 bands in SFG spectra. In addition, new information is obtained. In particular, if two types of molecular conformations are assumed, the C planes of the two molecules must be perpendicular to each other. (C) 2008 Elsevier B.V. All rights reserved.
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Guyetand, O., Gisselbrecht, M., Huetz, A., Agostini, P., Carre, B., Breger, P., Gobert, O., Garzella, D., Hergott, J. - F., Tcherbakoff, O., Merdji, H., Bougeard, M., Rottke, H., Boettcher, M., Ansari, Z., Antoine, P., & DiMauro, L. F. (2008). Complete momentum analysis of multi-photon photo-double ionization of xenon by XUV and infrared photons. JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS, 41(6).
Résumé: Photo-double ionization (PDI) of xenon by the Ti: Sapphire laser fundamental frequency combined to its 19th and 25th harmonics has been studied by means of a momentum imaging spectrometer. The measurement of the two emitted photoelectrons' momenta and their energy and angular correlations gives insight into the various mechanisms leading to PDI. Although the conditions for non-sequential direct photo-double ionization are fulfilled in the experiment, it is found that the two-step processes dominate.
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Guyetand, O., Gisselbrecht, M., Huetz, A., Agostini, P., Taieb, R., Maquet, A., Carre, B., Breger, P., Gobert, O., Garzella, D., Hergott, J. - F., Tcherbakoff, O., Merdji, H., Bougeard, M., Rottke, H., Boettcher, M., Ansari, Z., & Antoine, P. (2008). Evolution of angular distributions in two-colour, few-photon ionization of helium. JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS, 41(5).
Résumé: Single ionization of helium by a superposition of selected XUV high harmonics and infrared radiation has been studied by a momentum imaging technique. The measured angular distributions of photoelectrons are compared to numerical time- dependent calculations, showing very good agreement after average. The calculated angular distributions appear to depend critically on the delay between harmonic and infrared pulses on the attosecond scale, and on the relative phases and intensities of the harmonics.
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Hamoudi, H., Dablemont, C., & Esaulov, V. A. (2008). Interaction of Li+ with a Au(100) surface. SURFACE SCIENCE, 602(14), 2486–2490.
Résumé: Results of a study of Li+ neutralisation on Au(1 0 0) are presented and compared with an earlier study of neutralisation on Au(1 1 1), where anomalously high neutralisation had been tentatively related to the existence of the L-bandgap and occupied surface state. Neutralisation probability on Au(1 0 0) has a similar magnitude to that on Au(1 1 1) and a similar incident energy dependence, though the electronic structure is different. These results for surfaces with high workfunctions are very unexpected, since significantly smaller values may be expected in a “traditional” picture of a Li+ ion departing from the surface. We can account for the relatively large value of the neutral fraction by considering that the Li(2s) level lies below the Fermi level at short atom-surface separations as this has been shown to be the case for the Cu surface by Goldberg et al. This allows electron capture at small distances and the surviving neutrals account well for the behaviour of the neutral fraction at energies above 500 eV but not at lower energies. This could be due to various reasons including intermediate Li- formation and non-adiabatic effects. (C) 2008 Published by Elsevier B.V.
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Hamoudi, H., Guo, Z., Prato, M., Dablemont, C., Zheng, W. Q., Bourguignon, B., Canepa, M., & Esaulov, V. A. (2008). On the self assembly of short chain alkanedithiols. PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 10(45), 6836–6841.
Résumé: A study of the self-assembly of nonane-alkanedithiol monolayers on gold in n-hexane and ethanol solvents is presented. Self-assembled monolayers (SAMs) are characterised by reflection-absorption infrared spectroscopy (RAIRS), sum frequency generation (SFG) and spectroscopic ellipsometry (SE) measurements. Data obtained for alkanethiols SAMs are also shown for comparison. The measurements show that nicely organized HSC(9)SH SAMs can be obtained in n-hexane provided that N(2)-degassed solutions are used and all preparation steps are performed in the absence of ambient light. SFG measurements show that these SAMs have free standing SH groups. Use of an un-degassed and/or light-exposed n-hexane solutions leads to a worse layer organization. Preparation in ethanol, even in degassed solutions with processing in the dark, leads to poorly organized layers and no sign of free-SH groups was observed.
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Hoffman, A., Lafosse, A., Michaelson, S., Bertin, M., & Azria, R. (2008). Nano size effects in the high resolution electron energy loss spectra and excitation function of hydrogenated diamond films. SURFACE SCIENCE, 602(18), 3026–3032.
Résumé: The present work studies the high resolution electron energy loss spectra (HR-EELS) and excitation function of hydrogenated diamond films composed of diamond grains of varying size of similar to 300, similar to 20 nm and similar to 5 nm. It is reported that HR-EELS modes associated with C-C lattice phonons are comparably more intense than modes associated with the C-H surface vibrational modes in the case of nano-crystal line compared to micro-crystalline diamond films. Excitation function measurements of the different modes show a pronounced maximum at similar to 8 eV for the nano-diamond films, whereas for micro-crystalline films similar modes showed maximum intensities at 13 eV with a smaller contribution at 8 eV. It is reported that the elastic electron reflectivity is substantially larger for the nano-diamond films, showing broad maxima at similar to 8 and similar to 13 eV in both cases. It is suggested that these effects are associated with the larger probability for inelastic scattering of electrons by lattice phonons mediated by scattering with internal grain boundaries and defects in the case of nano-crystalline diamond films. (C) 2008 Elsevier B.V. All rights reserved.
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Journel, L., Guillemin, R., Haouas, A., Lablanquie, P., Penent, F., Palaudoux, J., Andric, L., Simon, M., Ceolin, D., Kaneyasu, T., Viefhaus, J., Braune, M., Li, W. B., Elkharrat, C., Catoire, F., Houver, J. - C., & Dowek, D. (2008). Resonant double Auger decay in carbon K-shell excitation of CO. PHYSICAL REVIEW A, 77(4).
Résumé: We have studied double Auger decay after C 1s -> 2 pi(*) photoexcitation in gas phase carbon monoxide. Two distinct processes, namely direct double Auger decay and cascade double Auger decay, are identified and studied in detail using multiple coincidence techniques. Cascade Auger decay is shown to be the overall dominant process. Decay channels involving the dissociation of the molecule followed by autoionization of the oxygen fragments are observed.
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Kazamias, S., Cassou, K., Ros, D., Ple, F., Jamelot, G., Klisnick, A., Lundh, O., Lindau, F., Persson, A., Wahlstroem, C. - G., de Rossi, S., Joyeux, D., Zielbauer, B., Ursescu, D., & Kuehl, T. (2008). Characterization of a transient collisional Ni-like molybdenum soft-x-ray laser pumped in grazing incidence. PHYSICAL REVIEW A, 77(3), 033812.
Résumé: We present experimental results from an extensive investigation of a Ni-like Mo x-ray laser pumped in the transient regime and GRIP configuration (GRazing Incidence Pumping). The pump laser is a 10 Hz, 1 J, Ti: sapphire laser system. The main diagnostic is a monochromatic near-field imaging system with a 1.7 micron spatial resolution that shows the soft-x-ray laser source size and position relative to the target surface. Changes of those characteristics are observed for different GRIP angles, varied between 15 and 21, while keeping all other parameters constant. Intense lasing is observed routinely at 18.9 nm with up to 3 microjoule output energy and stable operation is demonstrated at 10 Hz. We have investigated the role of several pumping parameters, in particular, the relative energy and delay between the long and short pulse. We show that this multiparameter scan leads to a well-defined optimal regime of operation and better understanding of the GRIP configuration. Finally, as the GRIP scheme requires careful tailoring of the plasma conditions to the specific soft-x-ray laser under investigation, we add a prepulse before the plasma producing long pulse to generate large-scale preplasmas. This increases the brightness of the soft-x-ray beam and leads to an almost Gaussian near-field spatial profile.
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Kheifets, A. S., Naja, A., Casagrande, E. M. S., & Lahmam-Bennani, A. (2008). DWBA-G calculations of electron impact ionization of noble gas atoms. JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS, 41(14).
Résumé: We perform calculations of electron impact ionization of noble gas atoms within the distorted wave Born approximation (DWBA) corrected by the Gamow factor (G) to account for the post-collision interaction. We make an extensive comparison with experimental data on He 1s(2), Ne 2s(2), 2p(6) and Ar 3p(6) under kinematics characterized by large energy transfer and close to minimum momentum transfer from the projectile to the target. For all atoms, good agreement between theory and experiment is achieved. In the case of Ar, the disagreement of experimental data with theory reported earlier by Catoire et al (2006 J. Phys. B: At. Mol. Opt. Phys. 39 2827) is reconciled.
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Lafosse, A., Bertin, M., Michaelson, S., Azria, R., Akhvlediani, R., & Hoffman, A. (2008). Surface defects induced by in-situ annealing of hydrogenated polycrystalline diamond studied by high resolution electron energy loss spectroscopy. DIAMOND AND RELATED MATERIALS, 17(6), 949–953.
Résumé: Plasma hydrogenation of polycrystalline diamond films results in a fully hydrogenated well-ordered diamond surface and etching of the amorphous phase located at grain boundaries. Vacuum annealing to 1000 degrees C followed by in-situ hydrogenation by thermal activated hydrogen of the bared diamond surface results in the formation of sp(3)-CH(x) adsorbed groups located on the top surface. Annealing of the in-situ hydrogenated surface to 600 degrees C results in desorption of these species and partial reconstruction of the film surface. Some irreversible surface degradation was detected in the in-situ annealed and hydrogenated surface compared to the state of the surface obtained upon plasma hydrogenation. (C) 2008 Elsevier B.V. All rights reserved.
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Lastapis, M., Martin, M., Riedel, D., & Dujardin, G. (2008). Role of the dopant in silicon on the dynamics of a single adsorbed molecule. Phys. Rev. B, 77(12), 125316.
Résumé: We investigate the role of the dopant in silicon on the dynamics of a single adsorbed molecule. We demonstrate that the dynamics of a single bistable molecule, a biphenyl molecule, adsorbed on a Si (100)-(2x1) surface is markedly dependent on the silicon type of doping (p or n) even though the electronic excitation and relaxation processes are unchanged. Both strongly and weakly chemisorbed individual biphenyl molecules are shown to interact differently with p- or n-doped Si (100) surfaces, thus inducing different stabilities of the adsorption configurations and different molecular dynamics. These effects rely on electrostatic interactions between distributed charges inside the molecule and charged surface states. The described phenomenon, which is a priori general, should be applicable to most of the molecules adsorbed on doped semiconductors having surface states in their band gap. This result is anticipated to have important applications in molecular electronic for positioning individual molecules with precision.
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Le Barbu-Debus, K., Broquier, M., Mahjoub, A., & Zehnacker-Rentien, A. (2008). Chiral recognition between alpha-hydroxylesters: A double-resonance IR/UV study of the complexes of methyl mandelate with methyl glycolate and methyl lactate. JOURNAL OF PHYSICAL CHEMISTRY A, 112(40), 9731–9741.
Résumé: Chiral recognition between alpha hydroxylesters has been studied in jet-cooled complexes of methyl mandelate with methyl lactate. The complex with nonchiral methyl glycolate has also been studied for the sake of comparison. The hydrogen-bond topology of the complexes has been interrogated by means of IR/UV double-resonance spectroscopy in the range of 3 μm. A theoretical approach has been conducted in conjunction with the experimental work to assist in the analysis of the spectra. Owing to the conformational flexibility of the subunits at play, emphasis has been put on the methodology used for the exploration of the potential-energy surface. The hydrogen-bond topology is very similar in the homo- and heterochiral complexes. It involves insertion of the hydroxyl group of methyl mandelate within the intramolecular hydrogen bond of methyl lactate or methyl glycolate, resulting in a five-membered ring. This contrasts with methyl lactate clusters previously studied by FTIR spectroscopy in a filet jet.(1).
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Le Padellec, A., Lievin, J., Staicu-Casagrande, E. M., Nzeyimana, T., Naji, E. A., & Urbain, X. (2008). Competitive processes in the associative ionization of C- with C+, N+, and O+. PHYSICAL REVIEW A, 78(6).
Résumé: Absolute integral cross sections have been measured for associative ionization reactions involving the C- and C+, N+, and O+ reactants. These measurements, obtained using a merged-beam setup in the keV range, provide us with useful experimental information on the efficiency and mechanisms of molecular ion formation from ionic reactants. The relative magnitudes of the different cross sections are rationalized by considering the spin multiplicities of initial and final states, and the exothermicities of the detachment and transfer ionization channels. The very different production efficiencies of CO+ ions via the O-+C+ and C-+O+ channels are explained by statistical and energetic considerations. The potential energy curves of CO and CO+ have been calculated by quantum ab initio methods in order to characterize the reactive pathways leading to autoionization. Thermal rate coefficients are derived to serve the plasma physics community.
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Lemaire, J. L., Fillion, J. H., Dulieu, F., Momeni, A., Baouche, S., Amiaud, L., & Cobut, V. (2008). Formation of molecules in the interstellar medium. In search for formation mechanisms of molecular H2 on the interstellar dust grains: the FORMOLISM experiment. Actual Chim., (315), III-IX.
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Lucas, B., Barat, M., Fayeton, J. A., Jouvet, C., Çarçabal, P., & Grégoire, G. (2008). Statistical versus non-statistical photo-fragmentation of protonated GWG tri-peptide induced by UV excitation. Chemical Physics, 347(1-3), 324–330.
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Lucas, B., Barat, M., Fayeton, J. A., Perot, M., Jouvet, C., Gregoire, G., & Brondsted Nielsen, S. (2008). Mechanisms of photoinduced Calpha[Single Bond]Cbeta bond breakage in protonated aromatic amino acids. J Chem Phys, 128(16), 164302.
Résumé: Photoexcitation of protonated aromatic amino acids leads to C(alpha)[Single Bond]C(beta) bond breakage among other channels. There are two pathways for the C(alpha)[Single Bond]C(beta) bond breakage, one is a slow process (microseconds) that occurs after hydrogen loss from the electronically excited ion, whereas the other is a fast process (nanoseconds). In this paper, a comparative study of the fragmentation of four molecules shows that the presence of the carboxylic acid group is necessary for this fast fragmentation channel to occur. We suggest a mechanism based on light-induced electron transfer from the aromatic ring to the carboxylic acid, followed by a fast internal proton transfer from the ammonium group to the negatively charged carboxylic acid group. The ion formed is a biradical since the aromatic ring is ionized and the carbon of the COOH group has an unpaired electron. Breakage of the weak C(alpha)[Single Bond]C(beta) bond gives two even-electron fragments and is expected to quickly occur. The present experimental results together with the ab initio calculations support the interpretation previously proposed.
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M.Wiesenmayer, M. B., S.Mathias, M.Wessendorf, E.V.Chulkov, V.M.Silkin, A.G.Borisov, J.P.Gauyacq, P.M.Echenique et M.Aeschlimann. (2008). Lifetime of an adsorbate excitation modified by a tunable two-dimensional substrate. Phys. Rev. B, 78, 245410.
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Mamatkulov, M., Stauffer, L., Sonnet, P., Mayne, A. J., Comtet, G., & Dujardin, G. (2008). Theoretical simulations of the tip-induced configuration changes of the 4,4 '-diacetyl-p-terphenyl molecule chemisorbed on Si(001). J. Chem. Phys., 128(24), 244710.
Résumé: We have investigated from a theoretical point of view modifications of the 4,4'-diacetyl-p-terphenyl molecule chemisorbed on Si(001) induced by the scanning tunneling microscope (STM). In previous experiments, these modifications were observed to occur preferentially at the end of the molecule after a +4.0 V voltage pulse and at the center after a +4.5 V voltage pulse. In the framework of ab initio simulations, we have realized a systematic energetic study of the dissociative chemisorption of one, two, or three phenyl rings of the substituted p-terphenyl molecule. Charge densities were then calculated for the investigated configurations and compared to the STM topographies. Before manipulation with the STM tip, the substituted p-terphenyl molecule is preferentially adsorbed without phenyl ring dissociation, allowing a partial rotation of the central phenyl ring. Our results show that the STM induced modifications observed at the end of the molecule might originate from the dissociation of two phenyl rings (one central and one external ring), while the modifications occurring at the central part of the molecule can be interpreted as a dissociation of the two external rings. (c) 2008 American Institute of Physics.
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Manson, J. R., Khemliche, H., & Roncin, P. (2008). Theory of grazing incidence diffraction of fast atoms and molecules from surfaces. Phys. Rev. B, 78(15), 155408.
Résumé: Prompted by recent experimental developments, a theory of surface scattering of fast atoms at grazing incidence is developed. The theory gives rise to a quantum-mechanical limit for ordered surfaces that describes coherent diffraction peaks whose thermal attenuation is governed by a Debye-Waller factor, however, this Debye-Waller factor has values much larger than would be calculated using simple models. A classical limit for incoherent scattering is obtained for high energies and temperatures. Between these limiting classical and quantum cases is another regime in which diffraction features appear that are broadened by the motion in the fast direction of the scattered beam but whose intensity is not governed by a Debye-Waller factor. All of these limits appear to be accessible within the range of currently available experimental conditions.
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Marinica, D. C., Borisov, A. G., & Shabanov, S. V. (2008). Bound States in the continuum in photonics. Phys. Rev. Lett., 100(18), 183902.
Résumé: With examples of two parallel dielectric gratings and two arrays of thin parallel dielectric cylinders, it is shown that the interaction between trapped electromagnetic modes can lead to scattering resonances with practically zero width. Such resonances are the bound states in the radiation continuum first discovered in quantum systems by von Neumann and Wigner. Potential applications of such photonic systems include: large amplification of electromagnetic fields within photonic structures and, hence, enhancement of nonlinear phenomena, biosensing, as well as perfect filters and waveguides for a particular frequency, and impurity detection.
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Meyer, M., Cubaynes, D., Glijer, D., Dardis, J., Hayden, P., Hough, P., Richardson, V., Kennedy, E. T., Costello, J. T., Radcliffe, P., Duesterer, S., Azima, A., Li, W. B., Redlin, H., Feldhaus, J., Taieb, R., Maquet, A., Grum-Grzhimailo, A. N., Gryzlova, E. V., & Strakhova, S. I. (2008). Polarization Control in Two-Color Above-Threshold Ionization of Atomic Helium. PHYSICAL REVIEW LETTERS, 101(19), 193002.
Résumé: Two-color multiphoton ionization of atomic helium was investigated by combining extreme ultraviolet (XUV) radiation from the Free Electron Laser in Hamburg with an intense synchronized optical laser. In the photoelectron spectrum, lines associated with direct ionization and above-threshold ionization show strong variations of their amplitudes as a function of both the intensity of the optical dressing field and the relative orientation of the linear polarization vectors of the two fields. The polarization dependence provides direct insight into the symmetry of the outgoing electrons in above-threshold ionization. In the high field regime, the monochromaticity of the XUV radiation enables the unperturbed observation of nonlinear processes in the optical field.
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Morisset, S., & Allouche, A. (2008). Quantum dynamic of sticking of a H atom on a graphite surface. JOURNAL OF CHEMICAL PHYSICS, 129(2).
Résumé: A quantum study of the sticking of a hydrogen atom chemisorbed onto graphite (0001) surface was carried out also including the phonon modes of the system in the collinear scattering approximation. A new model was developed to extract the substrate vibrational modes from density functional theory (DFT) calculation and include them in the total system dynamics. The resulting coupled-channel equations are numerically developed along time using the wave packet methods. The sticking coefficients are calculated for hydrogen atoms incident energies ranging from 0.17 and 1.3 eV for a surface temperature of 10 K and between 0.17 and 0.2 eV for a surface temperature of 150 K. The results are found to be in good agreement with the experimental work. (C) 2008 American Institute of Physics.
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Naja, A., Casagrande, E. M. S., Lahmam-Bennani, A., Stevenson, M., Lohmann, B., Dal Cappello, C., Bartschat, K., Kheifets, A., Bray, I., & Fursa, D. V. (2008). (e, 2e) triple differential cross-sections for ionization beyond helium: the neon case at large energy transfer. JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS, 41(8).
Résumé: We report new coplanar (e, 2e) results for ionization of the He 1s and Ne 2p and 2s subshells under kinematics which have remained rather unexplored to date and characterized by large energy transfer and close to minimum momentum transfer from the projectile to the target. The experimental results obtained in two laboratories are used as a sensitive test of a number of state-of-the-art available theoretical models for multi-electron atoms. The He results are in excellent agreement with convergent close-coupling predictions as well as with distorted-wave + Gamow and hybrid distorted-wave + R-matrix models. In the Ne case, an overall satisfactory agreement with experiments is obtained for all considered models. The importance of post-collisional interaction effects is demonstrated whereas second-order effects in the projectile-target interaction at small distances are shown to be negligibly small. Remaining discrepancies between theories and experiments are discussed.
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Oughaddou, H., Aufray, B., Biberian, J. P., Ealet, B., Le Lay, G., Treglia, G., Kara, A., & Rahman, T. S. (2008). Self-organization of Ge tetramers on Ag(001) surface: A 2D realization of unusual substrate mediated interactions. SURFACE SCIENCE, 602(2), 506–510.
Résumé: Scanning tunneling microscopy (STM) images recorded during dissolution of a half-monolayer Ge on a Ag(0 0 1) show that it proceeds by the disappearance of tetramer entities. Moreover, they reveal that the successive slowing down in the kinetics, observed during this dissolution, correspond to the formation of ordered 2D arrangements of tetramer vacancies. A lattice gas analysis of the latter predicts a very unusual sequence of pair interactions between these vacancies, probably mediated by the substrate. (C) 2007 Elsevier B.V. All rights reserved.
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Pino, T., Dartois, E., Cao, A. - T., Carpentier, Y., Chamaille, T., Vasquez, R., Jones, A. P., d'Hendecourt, L., & Brechignac, P. (2008). The 6.2 μm band position in laboratory and astrophysical spectra: a tracer of the aliphatic to aromatic evolution of interstellar carbonaceous dust. ASTRONOMY & ASTROPHYSICS, 490(2), 665–672.
Résumé: Context. The infrared emission features observed in the mid-infrared wavelength range in astronomical objects, often called the Aromatic Infrared Bands, exhibit differences in shape and position. Three astrophysical spectral classes have been proposed based on the spectral characteristics. The band positions in most sources are similar to those of aromatic materials, however, the exact nature of the emitters is still unknown. Aims. The spectral diversity of the bands provides a clue to the nature of the materials. An evolutionary scenario for the nature of the emitters can be inferred by comparison with laboratory analogues. Methods. The laboratory spectra of a wide range of soot material samples were recorded and a global analysis of the infrared absorption spectra performed. This spectral analysis, allied to the band shape and position variations, were then used to interpret the diversity and evolution of the features in the astronomical spectra. Results. We find correlations between the spectral regions characteristic of the CC and CH modes and use these to shed light on the origin of the infrared emission features. In particular, the observed shift in the position of the 6.2-6.3 μm band is shown to be a key tracer of the evolution of the aliphatic to aromatic component of carbonaceous dust.
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Poisson, L., Shafizadeh, N., & Haacke, S. (2008). Femtosecond dynamic of complexe molecules. ACTUALITE CHIMIQUE, (317), 62–64.
Résumé: Electronic relaxation is the first step in photochemistry which either guides these systems into the reacting states or dissipates the energy to form non reactive states and stop photochemistry. This relaxation operates often at femtosecond time scales, driven by molecular movements. It has become possible to explore these relaxation processes in many complex systems by femtosecond pump probe methods to investigate the flux of energy leading to photochemistry or stopping photochemistry. Gas phase methods are specifically interesting to understand the initial processes in these systems, for instance in photochromic molecules and metalloporphyrins. In the liquid phase, femtosecond fluorescence up-conversion methods combine temporal and spectral resolution. This combination offers a clearer picture of the nature of the excited population and its de-excitation.
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Quijada, M., Borisov, A. G., & Muino, R. D. (2008). Time-dependent density functional calculation of the energy loss of antiprotons colliding with metallic nanoshells. Phys. Status Solidi, 205(6), 1312–1316.
Résumé: Time-dependent density functional theory is used to study the interaction between antiprotons and metallic nanoshells. The ground state electronic proper-ties of the nanoshell are obtained in the jellium approximation. The energy lost by the antiproton during the collision is calculated and compared to that suffered by antiprotons traveling in metal clusters. The resulting energy loss per unit path length of material in thin nanoshells is larger than the corresponding quantity for clusters. It is shown that the collision process can be interpreted as the antiproton crossing of two nearly bi-dimensional independent metallic systems. (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Reddish, T. J., Colgan, J., Bolognesi, P., Avaldi, L., Gisselbrecht, M., Lavollee, M., Pindzola, M. S., & Huetz, A. (2008). Physical interpretation of the “kinetic energy release” effect in the double photoionization of H(2). PHYSICAL REVIEW LETTERS, 100(19), 193001.
Résumé: A physical interpretation is given for the variation with internuclear separation of the fully differential cross section for double photoionization of H2. This effect is analyzed in a geometry where the fourbody interaction is completely probed. Excellent agreement is found between experiment and time-dependent close-coupling theory after convoluting the latter over the relevant solid angles. We show the observed variations are purely due to the epsilon(Sigma) component of the polarization vector epsilon along the molecular axis, a conclusion which is supported through calculations of the photoionization of H2(+).
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Romanzin, C., Gans, B., Douin, S., Boye-Peronne, S., & Gauyacq, D. (2008). 193 nm photolysis of CHCl3: Probe of the CH product by CRDS. CHEMICAL PHYSICS, 351(1-3), 77–82.
Résumé: The CH radical production induced by 193 nm two-photon photolysis ofCHC13 has been measured for the first time via the cavity ring-down absorption spectroscopy of its A-X bands, using a commercial nanosecond pulsed dye laser. The range of pressure and laser intensity, as well as the time window detection, have been carefully chosen to ensure a constant CH number density during the measurement and to avoid post-photolysis reactivity. Internal energy distribution of the CH((XII)-I-2) fragment has been derived from population distribution simulations, leading to an average vibrational temperature T-vib = 1900 +/- 50 K and rotational temperature Tr t = 300 +/- 20 K. Two competing mechanisms can be i nvoked for the CH production channel: either two-photon absorption via resonant excited states of CHCl3 leading to dissociation of excited CHCl3, or two-photon sequential dissociation via the formation of the vibrationally excited CHCl2 fragment. The latter mechanism is proposed to be the prominent process for CH formation. (c) 2008 Elsevier B.V. All rights reserved.
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Saugout, S., Charron, E., & Cornaggia, C. (2008). H2 double ionization with few-cycle laser pulses. PHYSICAL REVIEW A, 77, 023404.
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Shafizadeh, N., Poisson, L., & Soep, B. (2008). Ultrafast electronic relaxation of excited state vitamin B(12) in the gas phase. CHEMICAL PHYSICS, 350(1-3), 2–6.
Résumé: The time evolution of electronically excited vitamin B(12) (cyanocobalamin) has been observed for the first time in the gas phase. It reveals an ultrafast decay to a state corresponding to metal excitation. This decay is interpreted as resulting from a ring to metal electron transfer. This opens the observation of the excited state of other complex biomimetic systems in the gas phase, the key to the characterisation of their complex evolution through excited electronic states. (C) 2007 Elsevier B.V. All rights reserved.
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Teperik, T. V., Garcia de Abajo, F. J., Borisov, A. G., Abdelsalam, M., Bartlett, P. N., Sugawara, Y., & Baumberg, J. J. (2008). Omnidirectional absorption in nanostructured metal surfaces. Nature Photon., 2(5), 299–301.
Résumé: Light absorbers available at present provide far from optimal black-body performance. The need for more efficient absorbers is particularly acute on the microscale, where they can play a significant role in preventing crosstalk between optical interconnects, and also as thermal light-emitting sources. Several efforts have been made in this context to achieve near-total but directionally dependent absorption using periodic grating structures(1-7). However, the ability to absorb light completely for any incident direction of light remains a challenge. Here we show that total omnidirectional absorption of light can be achieved in nanostructured metal surfaces that sustain localized optical excitations. The effect is realized over a full range of incident angles and can be tuned throughout the visible and near-infrared regimes by scaling the nanostructure dimensions. We suggest that surfaces displaying omnidirectional absorption will play a key role in devising efficient photovoltaic cells in which the absorbed light leads to electron-hole pair production.
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Thissen, R., Bizau, J. M., Blancard, C., Coreno, M., Dehon, C., Franceschi, P., Giuliani, A., Lemaire, J., & Nicolas, C. (2008). Photoionization cross section of Xe(+) ion in the pure 5p(5) (2)P(3/2) ground level. PHYSICAL REVIEW LETTERS, 100(22), 223001.
Résumé: Coupling an ion trap with synchrotron radiation is shown here to be a powerful approach to measure photoionization cross sections on ionic species relaxed in their ground state. The photoionization efficiency curve of Xe(+) ions stored in a Fourier transform ion cyclotron resonance ion trap was recorded at ELETTRA in the 20-23 eV photon energy range. Absolute cross sections were derived by comparison of the photoionization yield of Xe(+) with measurements from the ASTRID merged-beam experiment. Multiconfiguration Dirac-Fock calculations were performed for the interpretation of these new data.
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Tuna, T., Chabot, M., Pino, T., Desesquelles, P., Le Padellec, A., Martinet, G., Barat, M., Lucas, B., Mezdari, F., Montagnon, L., Van-Oanh, N. T., Lavergne, L., Lachaize, A., Carpentier, Y., & Beroff, K. (2008). Fragmentation branching ratios of highly excited hydrocarbon molecules C(n)H and their cations C(n)H(+) (n <= 4). JOURNAL OF CHEMICAL PHYSICS, 128(12).
Résumé: We have measured fragmentation branching ratios of neutral C(n)H and C(n)H(+) cations produced in high velocity (4.5 a.u) collisions between incident C(n)H(+) cations and helium atoms. Electron capture gives rise to excited neutral species C(n)H and electronic excitation to excited cations C(n)H(+). Thanks to a dedicated setup, based on coincident detection of all fragments, the dissociations of the neutral and cationic parents were recorded separately and in a complete way. For the fragmentation of C(n)H, the H-loss channel is found to be dominant, as already observed by other authors. By contrast, the H-loss and C-loss channels equally dominate the two-fragment break up of C(n)H(+) species. For these cations, we provide the first fragmentation data (n > 2). Results are also discussed in the context of astrochemistry. (c) 2008 American Institute of Physics.
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Turowski, M., Gronowski, M., Boye-Peronne, S., Douin, S., Moneron, L., Crepin, C., & Kolos, R. (2008). The C(3)N(-) anion: First detection of its electronic luminescence in rare gas solids. JOURNAL OF CHEMICAL PHYSICS, 128(16).
Résumé: The 193 nm laser irradiation of cyanoacetylene (HCCCN) that was isolated in rare gas solids led to a long-lived luminescence (origin at 3.58 eV), which was assigned to the (a) over tilde (3)Sigma(+)-(X) over tilde (1)Sigma(+) system of cyanoacetylide (CCCN(-)). The identification, which involved (15)N and (2)H isotopic substitution studies, is based on vibronic spacings in the phosphorescence spectrum (compared to previous infrared absorption measurements and to theoretical results regarding CCCN(-) vibrational frequencies), as well as on a BD(T)/cc-pVTZ prediction for the singlet-triplet energy gap in this anion (3.61 eV). The same emission was also generated from Kr/HC(3)N mixtures subjected to a glow electric discharge immediately before the solidification (cold-window-radial-discharge technique).
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Valdes, J. E., Vargas, P., Celedon, C., Sanchez, E., Guillemot, L., & Esaulov, V. A. (2008). Electronic density corrugation and crystal azimuthal orientation effects on energy losses of hydrogen ions in grazing scattering on a Ag(110) surface. PHYSICAL REVIEW A, 78(3).
Résumé: We present a detailed study of the energy losses of hydrogen ions that are scattered off an Ag (110) single-crystal surface for primary energies between 1 and 4 keV. We performed measurements for grazing angles as a function of crystal azimuthal orientation, which show large differences in energy losses. Experimental results are discussed by means of trajectory calculations of protons scattered under grazing-incidence conditions on the surface. Using nonlinear models for the stopping power, ab initio crystal structure calculations of the electronic density, and semiclassical simulations, we obtain data that are in very good agreement with experimental results. These simulations allow us to properly take into account the variations of the surface electronic density and hence obtain an accurate description of the energy loss processes for ion scattering along various azimuthal orientations of the target.
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Yang, H., Baffou, G., Mayne, A. J., Comtet, G., Dujardin, G., & Kuk, Y. (2008). Topology and electron scattering properties of the electronic interfaces in epitaxial graphene probed by resonant tunneling spectroscopy. Phys. Rev. B, 78(4), 041408.
Résumé: Z-V scanning tunneling spectroscopy is used to probe the topology and electron scattering properties of the electronic interfaces of monolayer and bilayer graphenes, expitaxially grown on SiC(0001). The dZ/dV spectra validate existing calculations of the interface topology and provide evidence for new electron scattering properties due to changes in the electronic character of the bonding. Two sharp boundaries are observed: between the vacuum and the graphene pi state lying above the graphene atom plane and a subsurface barrier between the carbon-rich layer and the bulk SiC.
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Zehnacker, A., & Suhm, M. A. (2008). Chirality recognition between neutral molecules in the gas phase. ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, 47(37), 6970–6992.
Résumé: Noncovalent interactions are particularly intriguing when they involve chiral molecules, because the interactions change in a subtle way upon replacing one of the partners by its mirror image. The resulting phenomena involving chirality recognition are relevant in the biosphere, in organic synthesis, and in polymer design. They may be classified according to the permanent or transient chirality of the interacting partners, leading to chirality discrimination, chirality induction, and chirality synchronization processes. For small molecules, high-level quantum chemical calculations for such processes are feasible. To provide reliable connections between theory and experiment, such phenomena are best studied in vacuum isolation at low temperature, using rotational, vibrational, electronic, and photoionization spectroscopy. We review these techniques and the results which have become available in recent years, with special emphasis on dimers of permanently chiral molecules and on the influence of conformational flexibility. Analogies between the microscopic mechanisms and macroscopic phenomena and between intra- and intermolecular cases are drawn.
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Actes de Conférences |
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Alcaraz, C., Carniato, V., Lecadre, F., Carcabal, P., Broquier, M., Dedonder-Lardeux, C., & Jouvet, C. (2008). A VUV line at the Server Laser at the Paris-Sud University Laser Center. In UVX 2008: 9E COLLOQUE SUR LES SOURCES COHERENTES ET INCOHERENTES UV (pp. 1–6). E D P SCIENCES.
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Blandin, P., Leveque-Fort, S., Lecart, S., Druon, F., Georges, P., Cossec, J. C., Potier, M. C., & Lenkei, Z. (2008). FRET detection in the plasma membrane using Total Internal Reflection Fluorescence Lifetime Imaging Microscopy. In 2008 CONFERENCE ON LASERS AND ELECTRO-OPTICS & QUANTUM ELECTRONICS AND LASER SCIENCE CONFERENCE (pp. 252–253).
Résumé: We developed a Total Internal Reflection Fluorescence Lifetime Imaging Microscope to perform functional imaging of living cells membranes labeled with FRET couples. Forster Resonance Energy Transfer efficiency can thus be followed with subwavelength axial resolution. (C) 2008 Optical Society of America
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Bundaleski, N., Khemliche, H., Rousseau, P., Cassimi, A., Soulisse, P., & Roncin, P. (2008). COLLISIONS OF IONS WITH INSULATOR SURFACES: CHARGING AND DISCHARGING DYNAMICS. In 24TH SUMMER SCHOOL AND INTERNATIONAL SYMPOSIUM ON THE PHYSICS OF IONIZED GASES (Vol. 133, 012016).
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Cafarelli, P., Carcabal, P., Champeaux, J. - P., Le Padellec, A., Moretto-Capelle, P., Rabier, J., & Sence, M. (2008). Ionization and Fragmentation of 5-Chlorouracil induced by 100 keV protons collisions. In AIP Conference Proceedings (Vol. 1080, pp. 71–77).
Résumé: We present preliminary experimental results on the dissociation of singly and doubly ionized 5-Chlorouracil induced by collisions with proton of 100 keV energy. Multiple coincidence techniques are used to detect the ionic fragments from single dissociation events. This enables a thorough analysis of kinetic momentums of the charged and neutral species involved in the dissociation. In many cases, this leads to the establishment of the scenario the molecule undergoes after ionization as well as the determination of the nature of intermediate (undetected) species. In other cases, the dissociation scenario cannot be unambiguously identified and further analysis as well as theoretical support is needed.
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Elkharrat, C., Picard, Y. J., Billaud, P., Houver, J. C., & Dowek, D. (2008). Electron-ion vector correlations for the study of photoionization of molecules in the UVX range: From synchrotron radiation to short light pulses. In UVX 2008: 9E COLLOQUE SUR LES SOURCES COHERENTES ET INCOHERENTES UV (pp. 35–43).
Résumé: Molecular frame photoemission is a very sensitive probe of the photoionization (PI) dynamics of molecules. The electron-ion vector correlation (VC) method takes advantage of dissociative photoionization (DPI) reactions of small molecules to measure such observables. It relies on the coincident detection of the photoelectron and the ion fragment emitted from the same DPI event and the determination of their velocity vectors. Most of the VC studies so far have been performed using synchrotron radiation (SR) light sources which benefit from a high repetition rate (1-10 MHz) favorable for coincidence experiments. In this paper we discuss the extension of this method to the study of PI processes induced by ultra-short VUV light sources, which provide the capability for investigating processes characterized by femtosecond or subfemtosecond dynamics. We first illustrate the VC method by the report of recent results of a comparative study of resonant photoionization of the H(2) and D(2) molecules induced by VUV circularly polarized synchrotron radiation at SOLEIL in the region involving resonant excitation of Q(1) and Q(2) doubly excited state series. This problem is of particular interest since autoionization and dissociation of selected Q, or Q(2) states occur on a comparable time scale of few femtoseconds, which implies a coupling between the electronic and nuclear motion. The extension of the VC method using femtosecond laser sources is then demonstrated by results for multiphoton PI of the Xe atom induced by 70 fs pulses centered at 400 nm delivered by the SOFOCKLE and PLFA Sources (SLIC, CEA-Saclay) after frequency doubling of a 1 kHz Ti:sapphire laser.
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Gauyacq, J. - P., Borisov, A. G., & Kazansky, A. K. (2008). Theoretical study of excited electronic states at surfaces, link with photo-emission and photo-desorption experiments. In 24TH SUMMER SCHOOL AND INTERNATIONAL SYMPOSIUM ON THE PHYSICS OF IONIZED GASES (Vol. 133, 012009).
Résumé: Excited electronic states at surfaces play a very important role in a variety of surface processes. These excited states have a finite lifetime due to electron-transfer processes and their efficiency as reaction intermediates depends crucially on their lifetime. A review of several physical situations, where an excited electronic state localized on an atom interacting with a metal surface intervenes in a surface process, is presented with an emphasis on the way the metal electronic structure influences the excited state dynamics. Examples are chosen among the alkali/metal systems, stressing how the same transient electronic state can influence different dynamical processes.
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Goddet, J. - P., Sebban, S., Guilbaud, O., Maynard, G., Cros, B., Gautier, J., Zeitoun, P., Valentin, C., Tissandier, F., Marchenko, T., Lambert, G., Benredjem, D., Boudaa, A., Klisnick, A., Ros, D., Kazamias, S., Cassou, K., Habib, J., Jamelot, G., Lagron, J. - C., Joyeux, D., De Rossi, S., Phalippou, D., Delmotte, F., Ravet, M. F., Calisti, A., Mocek, T., Kozlova, M., & Jakubczak, K. (2008). Spatio-temporal characterization of an injected XUV laser. In UVX 2008: 9E COLLOQUE SUR LES SOURCES COHERENTES ET INCOHERENTES UV (pp. 51–56).
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Guilbaud, O., Ros, D., Kazamias, S., Zielbauer, B., Habib, J., Pittman, M., Cassou, K., Ple, F., Farinet, M., Klisnick, A., de Dortan, F., Lacombe, S., Porcel, E., Le Sech, C., du Penhoat, M. - A., Touati, A., Marsi, M., Fajardo, M., Zeitoun, P., & Joyeux, D. (2008). LASERIX: first record from the plant. In UVX 2008: 9E COLLOQUE SUR LES SOURCES COHERENTES ET INCOHERENTES UV (pp. 57–63).
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Habib, J., Klisnick, A., Guilbaud, O., Joyeux, D., Zielbauer, B., Kazamias, S., Pittman, M., Ros, D., & de Dortan, F. (2008). Temporal coherence and spectral linewidth of XUV transitory lasers pumped in grazing incidence. In UVX 2008: 9E COLLOQUE SUR LES SOURCES COHERENTES ET INCOHERENTES UV (pp. 157–161).
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Khemliche, H., Soulisse, P., Bundaleski, N., & Roncin, P. (2008). SURFACE AND THIN FILM ANALYSIS USING GRAZING INCIDENCE FAST ATOM DIFFRACTION (GIFAD). In Publications of the Astronomical Observatory of Belgrade (Vol. 84, p. 142).
Résumé: Grazing collisions at surfaces offer rather contrasted conditions. For well ordered flat surfaces, the scattering is spread among several lattice sites, each of which produces only a tiny elementary deflection. If, in addition, the atomic projectile is aligned along a crystallographic direction, the surface appears as made of parallel furrows which act as a diffraction grating for the atomic wave. We will show that the analysis of characteristic diffraction pattern recorded on the position sensitive detector located downstream allow a sensitive measure of the shape of the surface electronic density. At variance, if a terrace edge or an ad-atom is sitting on the surface along the trajectory, a quasi-binary collision will follow in which energy and momentum conservation allow identification of the mass of the collision partner.
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Pino, T., Cao, A. T., Carpentier, Y., Dartois, E., d'Hendecourt, L., & Brechignac, P. (2008). Laboratory analogues of hydrocarbonated interstellar nanograins. In IAU: ORGANIC MATTER IN SPACE (Vol. 4, pp. 393–394).
Résumé: Carbonaceous extraterrestrial matter is observed in a wide variety of astrophysical environments. The spectroscopic signatures revealed a large variety of chemical structure illustrating the rich carbon chemistry that occurs in space. In order to produce laboratory analogues of carbonaceous cosmic dust, a new chemical reactor has been built, in the Laboratoire de Photophysique Moleculaire. It is a low pressure flat burner providing flames of premixed hydrocarbon/oxygen gas mixtures, closely following the model system used by the combustion community. hi such a device the flame is a one-dimensional chemical reactor that, offers a broad range of combustion conditions and sampling which allows production of many and various by-products hi the present work, we studied: i) the infrared transmission spectra of thin film deposit samples whose nature ranges from strongly aromatic to strongly aliphatic materials; ii) Hie resonant two-photon photoionisation spectra of gas phase PAHs formed in the flame.
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Rousseau, P., Khemliche, H., Bundaleski, N., Soulisse, P., Momeni, A., & Roncin, P. (2008). Surface analysis with grazing incidence fast atom diffraction (GIFAD). In 24TH SUMMER SCHOOL AND INTERNATIONAL SYMPOSIUM ON THE PHYSICS OF IONIZED GASES (Vol. 133, 012013).
Résumé: Grazing collisions at surfaces offer rather contrasted conditions. For well ordered flat surfaces, the scattering is spread among several lattice sites, each of which produces only a tiny elementary deflection. If, in addition, the atomic projectile is aligned along a crystallographic direction, the surface appears as made of parallel furrows or as a washboard which act as a diffraction grating for the atomic wave. We will show that the analysis of characteristic diffraction pattern recorded on a position sensitive detector located downstream allows a sensitive measure of the shape of the surface electronic density. A modified Debye Waller factor is proposed to explain the observed diffraction signal.
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Chapitres de Livres |
Mayne, A. J., & Dujardin, G. (2008). STM manipulation and Dynamics. In Dynamics (Vol. 3, pp. 681–759). Handbook of Surface Science. E. Hasselbrink and B.I. Lundqvist.
Résumé: This volume of the Handbook of Surface Science covers all aspects of the dynamics of surface processes. Two dozen world leading experts in this field address the subjects of energy exchange in gas atoms, surface collisions, the rules governing dissociative adsorption on surfaces, the formation of nanostructures on surfaces by self-assembly, and the study of surface phenomena using ultra-fast lasers. The chapters are written for both newcomers to the field as well as researchers.
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