Magazine Articles |
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Bourg N., S. S., Dupuis G., Lévêque-Fort S. (2015). De la microscopie à la nanoscopie de fluorescence. L'actualité Chimique, (397-398), 35–40.
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Farcy, R., Benoit, C., Moustie, R., Eyrignoux, T., Beaumel, P., Toullec, A., & Fontaine-Aupart, M. P. (2015). Aiguille fibrée pour l’aide au diagnostic du cancer du sein par fluorescence endogène. Photoniques, 79, 22–25.
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Keller A., & Milman P. (2015). La téléportation révolutionne la communication. La Recherche, 501(Juillet).
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Peer-reviewed Publications |
Abed, N., Said-Hassane, F., Zouhiri, F., Mougin, J., Nicolas, V., Desmaele, D., Gref, R., & Couvreur, P. (2015). An efficient system for intracellular delivery of beta-lactam antibiotics to overcome bacterial resistance. Scientific Reports, 5.
Résumé: The “Golden era” of antibiotics is definitely an old story and this is especially true for intracellular bacterial infections. The poor intracellular bioavailability of antibiotics reduces the efficency of many treatments and thereby promotes resistances. Therefore, the development of nanodevices coupled with antibiotics that are capable of targeting and releasing the drug into the infected-cells appears to be a promising solution to circumvent these complications. Here, we took advantage of two natural terpenes (farnesyl and geranyl) to design nanodevices for an efficient intracellular delivery of penicillin G. The covalent linkage between the terpene moieties and the antibiotic leads to formation of prodrugs that self-assemble to form nanoparticles with a high drug payload between 55-63%. Futhermore, the addition of an environmentally-sensitive bond between the antibiotic and the terpene led to an efficient antibacterial activity against the intracellular pathogen Staphylococcus aureus with reduced intracellular replication of about 99.9% compared to untreated infected cells. Using HPLC analysis, we demonstrated and quantified the intracellular release of PenG when this sensitive-bond (SB) was present on the prodrug, showing the success of this technology to deliver antibiotics directly into cells.
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Agostoni, V., Horcajada, P., Noiray, M., Malanga, M., Aykac, A., Jicsinszky, L., Vargas-Berenguel, A., Semiramoth, N., Daoud-Mahammed, S., Nicolas, V., Martineau, C., Taulelle, F., Vigneron, J., Etcheberry, A., Serre, C., & Gref, R. (2015). A “green” strategy to construct non-covalent, stable and bioactive coatings on porous MOF nanoparticles. Scientific Reports, 5, 7925.
Résumé: Nanoparticles made of metal-organic frameworks (nanoMOFs) attract a growing interest in gas storage, separation, catalysis, sensing and more recently, biomedicine. Achieving stable, versatile coatings on highly porous nanoMOFs without altering their ability to adsorb molecules of interest represents today a major challenge. Here we bring the proof of concept that the outer surface of porous nanoMOFs can be specifically functionalized in a rapid, biofriendly and non-covalent manner, leading to stable and versatile coatings. Cyclodextrin molecules bearing strong iron complexing groups (phosphates) were firmly anchored to the nanoMOFs' surface, within only a few minutes, simply by incubation with aqueous nanoMOF suspensions. The coating procedure did not affect the nanoMOF porosity, crystallinity, adsorption and release abilities. The stable cyclodextrin-based coating was further functionalized with: i) targeting moieties to increase the nanoMOF interaction with specific receptors and ii) poly(ethylene glycol) chains to escape the immune system. These results pave the way towards the design of surface-engineered nanoMOFs of interest for applications in the field of targeted drug delivery, catalysis, separation and sensing.
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Alata, I., Jallat, A., Gavilan, L., Chabot, M., Cruz-Diaz, G. A., Munoz Caro, G. M., Béroff, K., & Dartois, E. (2015). Vacuum ultraviolet of hydrogenated amorphous carbons. A&A, 584, A123.
Résumé: Context. Hydrogenated amorphous carbons (a–C:H) are a major component of the carbonaceous solids present in the interstellar medium. The production and existence of these grains is connected in particular with the balance between their photolysis, radiolysis, and hydrogenation. During grain processing, H2 and other small organic molecules, radicals, and fragments are released into the gas phase.
Aims. We perform photolytic experiments on laboratory produced interstellar a–C:H analogues to monitor and quantify the release of species and compare to relevant observations in the interstellar medium.
Methods. Hydrogenated amorphous carbon analogues at low temperature are exposed to ultraviolet (UV) photons, under ultra-high vacuum conditions. The species produced are monitored using mass spectrometry and post irradiation temperature-programmed desorption. Additional experiments are performed using deuterated analogues and the species produced are unambiguously separated from background contributions. We implement the laboratory measured yields for the released species in a time dependent model to investigate the effect of the UV photon irradiation of hydrogenated amorphous carbons in a photon dominated region, and estimate the associated time scale.
Results. The UV photolysis of hydrogenated amorphous carbons leads to the production of H2 molecules and small hydrocarbons. The model shows that the photolytic evolution of a–C:Hs in photon dominated regions, such as the Horsehead Nebula, can raise the abundance of carbonaceous molecules by several orders of magnitude at intermediate visual extinctions, i.e., after the C+ maximum and before the dense cloud conditions prevail where models generally show a minimum abundance for such carbonaceous species. The injection time peak ranges from a thousand to ten thousand years in the models, considering only the destruction of such grains and no re-hydrogenation. This time scale is consistent with the estimated advection front of a photon dominated region, which replenishes it with freshly exposed material.
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Alata, I., Scuderi, D., Lepere, V., Steinmetz, V., Gobert, F., Thiao-Layel, L., Le Barbu-Debus, K., & Zehnacker-Rentien, A. (2015). Exotic Protonated Species Produced by UV-Induced Photofragmentation of a Protonated Dimer: Metastable Protonated Cinchonidine. Journal Of Physical Chemistry A, 119(39), 10007–10015.
Résumé: A metastable protonated cinchona alkaloid was produced in the gas phase by UV-induced photodissociation (UVPD) of its protonated dimer in a Paul ion trap. The infrared multiple photon dissociation (IRMPD) spectrum of the molecular ion formed by UVPD was obtained and compared to DFT calculations to characterize its structure. The protonation site obtained thereby is not accessible by classical protonation ways. The protonated monomer directly formed in the ESI source or by collision-induced dissociation (CID) of the dimer undergoes protonation at the most basic alkaloid nitrogen. In contrast, protonation occurs at the quinoline aromatic ring nitrogen in the UVPD-formed monomer.
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Alauddin, M., Gloaguen, E., Brenner, V., Tardivel, B., Mons, M., Zehnacker-Rentien, A., Declerck, V., & Aitken, D. J. (2015). Intrinsic Folding Proclivities in Cyclic β-Peptide Building Blocks: Configuration and Heteroatom Effects Analyzed by Conformer-Selective Spectroscopy and Quantum Chemistry. Chem. Eur. J., 21(46), 16479–16493.
Résumé: This work describes the use of conformer-selective laser spectroscopy following supersonic expansion to probe the local folding proclivities of four-membered ring cyclic β-amino acid building blocks. Emphasis is placed on stereochemical effects as well as on the structural changes induced by the replacement of a carbon atom of the cycle by a nitrogen atom. The amide A IR spectra are obtained and interpreted with the help of quantum chemistry structure calculations. Results provide evidence that the building block with a trans-substituted cyclobutane ring has a predilection to form strong C8 hydrogen bonds. Nitrogen-atom substitution in the ring induces the formation of the hydrazino turn, with a related but distinct hydrogen-bonding network: the structure is best viewed as a bifurcated C8/C5 bond with the N heteroatom lone electron pair playing a significant acceptor role, which supports recent observations on the hydrazino turn structure in solution. Surprisingly, this study shows that the cis-substituted cyclobutane ring derivative also gives rise predominantly to a C8 hydrogen bond, although weaker than in the two former cases, a feature that is not often encountered for this building block.
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Amiaud, L., Fillion, J. - H., Dulieu, F., Momeni, A., & Lemaire, J. - L. (2015). Physisorption and desorption of H2, HD and D2 on amorphous solid water ice. Effect on mixing isotopologue on statistical population of adsorption sites. Phys Chem Chem Phys, 17(44), 30148–30157.
Résumé: We study the adsorption and desorption of three isotopologues of molecular hydrogen mixed on 10 ML of porous amorphous water ice (ASW) deposited at 10 K. Thermally programmed desorption (TPD) of H2, D2 and HD adsorbed at 10 K have been performed with different mixings. Various coverages of H2, HD and D2 have been explored and a model taking into account all species adsorbed on the surface is presented in detail. The model we propose allows to extract the parameters required to fully reproduce the desorption of H2, HD and D2 for various coverages and mixtures in the sub-monolayer regime. The model is based on a statistical description of the process in a grand-canonical ensemble where adsorbed molecules are described following a Fermi-Dirac distribution.
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Arabei, S., McCaffrey, J. G., Galaup, J. - P., Shafizadeh, N., & Crepin, C. (2015). Stimulated emission in cryogenic samples doped with free-base tetraazaporphine. PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 17(22), 14931–42.
Résumé: Thin cryogenic samples of inert gas solids doped with free-base tetraazaporphine (H2TAP) were irradiated with a tunable pulsed laser. Under resonant electronic excitation of the guest, specific vibronic transitions of the fluorescence spectra were found to be strongly enhanced with only a moderate increase of the laser power. This enhancement is due to stimulated emission (SE). The characteristics of SE bands are described in the three hosts (Ar, N2, and Ne) explored, as well as their excitation spectra. SE is observed in transitions involving different vibrational modes of the guest, depending on the host and the electronic excitation. The results are discussed in comparison with previous works on other tetrapyrrolic molecules trapped in inert gas matrices. From this comparison the key features required to observe SE are deduced to be: (1) SE can be obtained with various tetrapyrrolic molecules; (2) free-base molecules are preferable to their metallo-counterparts; (3) the results highlight a specific molecular vibrational mode involved in the process; and (4) cryogenic crystal structures are also of importance in the detection of SE.
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Barbry, M., Koval, P., Marchesin, F., Esteban, R., Borisov, A. G., Aizpurua, J., & Sanchez-Portal, D. (2015). Atomistic near-field nanoplasmonics: reaching atomic-scale resolution in nanooptics. Nano Lett., 15(5), 3410–3419.
Résumé: Electromagnetic field localization in nanoantennas is one of the leitmotivs that drives the development of plasmonics. The near-fields in these plasmonic nanoantennas are commonly addressed theoretically within classical frameworks that neglect atomic-scale features. This approach is often appropriate since the irregularities produced at the atomic scale are typically hidden in far-field optical spectroscopies. However, a variety of physical and chemical processes rely on the fine distribution of the local fields at this ultraconfined scale. We use time-dependent density functional theory and perform atomistic quantum mechanical calculations of the optical response of plasmonic nanoparticles, and their dimers, characterized by the presence of crystallographic planes, facets, vertices, and steps. Using sodium clusters as an example, we show that the atomistic details of the nanoparticles morphologies determine the presence of subnanometric near-field hot spots that are further enhanced by the action of the underlying nanometric plasmonic fields. This situation is analogue to a self-similar nanoantenna cascade effect, scaled down to atomic dimensions, and it provides new insights into the limits of field enhancement and confinement, with important implications in the optical resolution of field-enhanced spectroscopies and microscopies.
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Barros M. R., Farías O. J., Keller A., Coudreau T., Milman P., & Walborn S. P. (2015). Detecting multipartite spatial entanglement with modular variables. Phys. Rev. A, 92, 022308.
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Bergeron, H., Czuchry, E., Gazeau, J. - P., Malkiewicz, P., & Piechocki, W. (2015). Singularity avoidance in a quantum model of the Mixmaster universe. Physical Review D, 92(12), 124018.
Résumé: We present a quantum model of the vacuum Bianchi-IX dynamics. It is based on four main elements. First, we use a compound quantization procedure: an affine coherent state quantization for isotropic variables and a Weyl quantization for anisotropic ones. Second, inspired by standard approaches in molecular physics, we make an adiabatic approximation (Born-Oppenheimer-like approximation). Third, we expand the anisotropy potential about its minimum in order to deal with its harmonic approximation. Fourth, we develop an analytical treatment on the semiclassical level. The resolution of the classical singularity occurs due to a repulsive potential generated by the affine quantization. This procedure shows that during contraction the quantum energy of anisotropic degrees of freedom grows much slower than the classical one. Furthermore, far from the quantum bounce, the classical recollapse is reproduced. Our treatment is put in the general context of methods of molecular physics, which can include both adiabatic and nonadiabatic approximations.
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Bergeron, H., Czuchry, E., Gazeau, J. - P., Malkiewicz, P., & Piechocki, W. (2015). Smooth quantum dynamics of the mixmaster universe. Physical Review D, 92(6), 061302.
Résumé: We present a new approach to the vacuum Bianchi IX model by combining affine coherent state quantization with Born-Oppenheimer-type adiabatic approximation in the analogy with quantum molecular physics. The analytical treatment is carried out on both quantum and semiclassical levels. Our quantization method by itself generates a specific repulsive potential that resolves the classical singularity. The quantized oscillatory degrees of freedom behave as radiation energy density. The Friedmann-like lowest-energy eigenstates of the system are found to be dynamically stable against small anisotropy perturbations, in contrast to the classical case.
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Bergeron, H., Dapor, A., Gazeau, J. P., & Małkiewicz, P. (2015). Smooth bounce in the affine quantization of a Bianchi I model. Phys. Rev. D, 91(12), 124002.
Résumé: We present the affine coherent state quantization of the Bianchi I model. As in our previous paper on quantum theory of Friedmann models, we employ a variable associated with a perfect fluid to play a role of clock. Then we deparametrize the model. A distinctive feature, absent in isotropic models, is an extra nonholonomic constraint, which survives the deparametrization and constrains the range of physical variables. The appearance of the constraint reflects the “amplification” of singularity due to anisotropy. The quantization smoothes the extra constraint and allows quantum contracting trajectories to be smoothly transformed into expanding ones. Making use of an affine coherent state we develop a semiclassical description. Figures are included to illustrate our result.
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Bizau, J. M., Cubaynes, D., Guilbaud, S., Al Shorman, M. M., Gharaibeh, M. F., Ababneh, I. Q., Blancard, C., & McLaughlin, B. M. (2015). K-shell photoionization of O+ and O2+ ions: Experiment and theory. Physical Review A, 92, 023401.
Résumé: Absolute cross sections for the single and double K-shell photoionization of carbonlike O2+ and nitrogenlike O+ ions were measured in the 526-620-eV photon energy range by employing the ion-photon merged-beam technique at the SOLEIL synchrotron radiation facility. High-resolution spectroscopy up to E/Lambda E approximate to 5300 was achieved. Rich resonance structures observed in the experimental spectra are analyzed and identified with the aid of R-matrix and multiconfiguration Dirac-Fock (MCDF) methods. For these two atomic oxygen ions of particular astrophysical interest we characterized the strong 1s -> 2p and the weaker 1s -> np (n > 2) resonances observed. A detailed comparison of the energies of the 1s -> 2p resonances in the first members of the oxygen isonuclear sequence measured by synchrotron based experiments and the Chandra and XMM-Newton x-ray satellites is presented.
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Bobrov K., K. N., Guillemot L. (2015). True perylene epitaxy on Ag(110) driven by site recognition effect. J. Chem. Phys., 142(10), 101929.
Résumé: We present a STM study of room temperature perylene adsorption on the Ag(110) surface. We have found a 2D perylene crystalline phase coexisting with the perylene liquid phase under thermal equilibrium. The reversible precipitation of the liquid phase at sub-monolayer coverage reveals the well ordered chiral crystalline phase existing in two enantiomorphic configurations of the ((-2)(3) (5)(2)) and ((2)(3) (5)(-2)) symmetry. This chiral phase is spatially separated into the 2D enantiopure islands of tens of nanometers size randomly distributed on the substrate and surrounded by the liquid medium. Analysis of surface registry of the crystalline phase combined with modeling of the intermolecular interactions indicates that its structure and symmetry is determined by a specific balance between the intermolecular attraction and intrinsic ability of the perylene aromatic board to recognize adsorption sites. The recognition effect was found to be strong enough to pin half of the perylene molecules into defined adsorption sites providing the structure skeleton. The attractive intermolecular interaction was found to be strong enough to bind another half of the molecules to the perylene skeleton shaping the true epitaxial structure.
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Bon, P., Bourg, N., Lecart, S., Monneret, S., Fort, E., Wenger, J., & Leveque-Fort, S. (2015). Three-dimensional nanometre localization of nanoparticles to enhance super-resolution microscopy. Nat Commun, 6, 7764.
Résumé: Meeting the nanometre resolution promised by super-resolution microscopy techniques (pointillist: PALM, STORM, scanning: STED) requires stabilizing the sample drifts in real time during the whole acquisition process. Metal nanoparticles are excellent probes to track the lateral drifts as they provide crisp and photostable information. However, achieving nanometre axial super-localization is still a major challenge, as diffraction imposes large depths-of-fields. Here we demonstrate fast full three-dimensional nanometre super-localization of gold nanoparticles through simultaneous intensity and phase imaging with a wavefront-sensing camera based on quadriwave lateral shearing interferometry. We show how to combine the intensity and phase information to provide the key to the third axial dimension. Presently, we demonstrate even in the occurrence of large three-dimensional fluctuations of several microns, unprecedented sub-nanometre localization accuracies down to 0.7 nm in lateral and 2.7 nm in axial directions at 50 frames per second. We demonstrate that nanoscale stabilization greatly enhances the image quality and resolution in direct stochastic optical reconstruction microscopy imaging.
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Boucher G., Douce T., Bresteau D., Walborn S. P., Keller A., Coudreau T., Ducci S., & Milman P. (2015). Toolbox for continuous-variable entanglement production and measurement using spontaneous parametric down-conversion. PHYSICAL REVIEW A, 92, 023804.
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Bouchet, A., Klyne, J., Piani, G., Dopfer, O., & Zehnacker, A. (2015). Diastereo-specific conformational properties of neutral, protonated and radical cation forms of (1R,2S)-cis- and (1R,2R)-trans-amino-indanol by gas phase spectroscopy. Physical Chemistry Chemical Physics, 17(39), 25809–25821.
Résumé: Chirality effects on the intramolecular interactions strongly depend on the charge and protonation states. Here, the influence of chirality on the structure of the neutral, protonated, and radical cation forms of (1R,2S)-cis- and (1R,2R)-trans-1-amino-2-indanol diastereomers, prototypical molecules with two chiral centers, is investigated in a molecular beam by laser spectroscopy coupled with quantum chemical calculations. The neutral systems are structurally characterised by double resonance IR-UV spectroscopy, while IR-induced dissociation spectroscopy is employed for the charged molecules. The sterical constraints due to the cyclic nature of the molecule emphasise the chirality effects, which manifest themselves by the formation of an intramolecular hydrogen bond in neutral or protonated (1R,2S)-cis-amino-indanol. In contrast, this interaction is not possible in (1R,2R)-trans-amino-indanol. In the protonated species, chirality also influences the spectroscopic probes in the NH/OH stretch range by fine-tuning subtle effects such as the hyperconjugation between the sigma(OH) orbital and sigma* orbitals localised on the alicyclic ring. The radical cation undergoes opening of the alicyclic ring, which results in an ionisation-induced loss of the chirality effects.
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Boulet, C., & Ma, Q. and T., R.H. (2015). Line mixing in parallel and perpendicular bands of CO2: A further refined Robert-Bonamy formalism. Journal of Chemical Physics, 143(12), 124313.
Résumé: Starting from the refined Robert-Bonamy formalism [Q. Ma, C. Boulet, and R. H. Tipping, J. Chem. Phys. 139, 034305 (2013)], we propose here an extension of line mixing studies to infrared absorptions of linear polyatomic molecules having stretching and bending modes. The present formalism does not neglect the internal degrees of freedom of the perturbing molecules, contrary to the energy corrected sudden (ECS) modelling, and enables one to calculate the whole relaxation matrix starting from the potential energy surface. Meanwhile, similar to the ECS modelling, the present formalism properly accounts for roles played by all the internal angular momenta in the coupling process, including the vibrational angular momentum. The formalism has been applied to the important case of CO2 broadened by N2. Applications to two kinds of vibrational bands (Σ → Σ and Σ → Π) have shown that the present results are in good agreement with both experimental data and results derived from the ECS model.
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Bourg, N., Mayet, C., Dupuis, G., Barroca, T., Bon, P., Lecart, S., Fort, E., & Leveque-Fort, S. (2015). Direct optical nanoscopy with axially localized detection. Nature Photonics, 9(9), 587–+.
Résumé: Evanescent light excitation is widely used in super-resolution fluorescence microscopy to confine light and reduce background noise. Here, we propose a method of exploiting evanescent light in the context of emission. When a fluorophore is located in close proximity to a medium with a higher refractive index, its near-field component is converted into light that propagates beyond the critical angle. This so-called supercritical-angle fluorescence can be captured using a high-numerical-aperture objective and used to determine the axial position of the fluorophore with nanometre precision. We introduce a new technique for three-dimensional nanoscopy that combines direct stochastic optical reconstruction microscopy (dSTORM) with dedicated detection of supercritical-angle fluorescence emission. We demonstrate that our approach of direct optical nanoscopy with axially localized detection (DONALD) typically yields an isotropic three-dimensional localization precision of 20 nm within an axial range of similar to 150 nm above the coverslip.
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Broquier, M., Soorkia, S., & Gregoire, G. (2015). A comprehensive study of cold protonated tyramine: UV photodissociation experiments and ab initio calculations. Phys Chem Chem Phys, 17, 25854–25862.
Résumé: We present a comprehensive experimental study of protonated tyramine ions in a cold 3D quadrupole ion trap coupled to a time-of-flight mass spectrometer. Multiple UV photodissociation techniques have been developed, including single and double resonance spectroscopy along with time-resolved excited state lifetime measurements through a picosecond pump-probe scheme. An original UV-UV hole burning method is presented which can be used without modification of the quadrupole ion trap. The electronic spectrum of the cold protonated tyramine exhibits well-defined vibronic transitions, allowing the firm assignment of its two low-lying energy conformations by comparison with CC2 ab initio excited state calculations.
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Calvo, F., Li, Y., Kiawi, D. M., Bakker, J. M., Parneix, P., & Janssens, E. (2015). Nonlinear effects in infrared action spectroscopy of silicon and vanadium oxide clusters: experiment and kinetic modeling. PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 17(39), 25956–25967.
Résumé: For structural assignment of gas phase compounds, infrared action spectra are usually compared to computed linear absorption spectra. However, action spectroscopy is highly nonlinear owing to the necessary transfer of the excitation energy and its subsequent redistribution leading to statistical ionization or dissociation. Here, we examine by joint experiment and dedicated modeling how such nonlinear effects affect the spectroscopic features in the case of selected inorganic clusters. Vibrational spectra of neutral silicon clusters are recorded by tunable IR-UV two-color ionization while IR spectra for cationic vanadium oxide clusters are obtained by IR multiphoton absorption followed by dissociation of the bare cluster or of its complex with Xe. Our kinetic modeling accounts for vibrational anharmonicities, for the laser interaction through photon absorption and stimulated emission rates, as well as for the relevant ionization or dissociation rates, all based on input parameters from quantum chemical calculations. Comparison of the measured and calculated spectra indicates an overall agreement as far as trends are concerned, except for the photodissociation of the V3O7+-Xe messenger complex, for which anharmonicities are too large and poorly captured by the perturbative anharmonic model. In all systems studied, nonlinear effects are essentially manifested by variations in the intensities as well as spectral broadenings. Differences in some band positions originate from inaccuracies of the quantum chemical data rather than specific nonlinear effects. The simulations further yield information on the average number of photons absorbed, which is otherwise unaccessible information: several to several tens of photons need to be absorbed to observe a band through dissociation, while three to five photons can be sufficient for detection of a band via IR-UV ionization.
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Chan, A. J., Steenkeste, K., Canette, A., Eloy, M., Brosson, D., Gaboriaud, F., & Fontaine-Aupart, M. - P. (2015). Natural Rubber-Filler Interactions: What Are the Parameters? Langmuir, 31(45), 12437–12446.
Résumé: Reinforcement of a polymer matrix through the incorporation of nanoparticles (fillers) is a common industrial practice that greatly enhances the mechanical properties of the composite material. The origin of such mechanical reinforcement has been linked to the interaction between the polymer and filler as well as the homogeneous dispersion of the filler within the polymer matrix. In natural rubber (NR) technology, knowledge of the conditions necessary to achieve more efficient NR-filler interactions is improving continuously. This study explores the important physicochemical parameters required to achieve NR-filler interactions under dilute aqueous conditions by varying both the properties of the filler (size, composition, surface activity, concentration) and the aqueous solution (ionic strength, ion valency). By combining fluorescence and electron microscopy methods, we show that NR and silica interact only in the presence of ions and that heteroaggregation is favored more than homoaggregation of silica-silica or NR-NR. The interaction kinetics increases with the ion valence, whereas the morphology of the heteroaggregates depends on the size of silica and the volume percent ratio (dry silica/dry NR). We observe dendritic structures using silica with a diameter (d) of 100 nm at a similar to 20-50 vol % ratio, whereas we obtain raspberry-like structures using silica with d = 30 nm particles. We observe that in liquid the interaction is controlled by the hydrophilic bioshell, in contrast to dried conditions, where hydrophobic polymer dominates the interaction of NR with the fillers. A good correlation between the nanoscopic aggregation behavior and the macroscopic aggregation dynamics of the particles was observed. These results provide insight into improving the reinforcement of a polymer matrix using NR-filler films.
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Chan, A. J., Steenkeste, K., Ely, M., Brssn, D., Gaboriaud, F., & Fontaine-Aupart, M. - P. (2015). Lipid Content In Small And Large Natural Rubber Particles. Rubber Chemistry And Technology, 88(2), 248–257.
Résumé: Knowledge of the surface composition of natural rubber (NR) latex is essential to manufacturers of latex goods. Films made from only small rubber particles (SRPs) and a mix of SRPs and large rubber particles (LRPs) differ in mechanical properties. The reason for this difference, which is still under debate, is hypothesized to be linked with biomolecules (proteins and lipids) present in the NR particle surface. In this study, we characterize the surface chemistry, particularly lipid content of the SRP and LRP, by performing investigations directly on these particles in aqueous conditions. Fluorescent probes were used to display protein and lipid affinity and analyze them in situ with steady-state fluorescence spectroscopy, fluorescence correlation spectroscopy, and fluorescence lifetime measurements. Results are atypical in showing that lipids are more abundant in LRPs than in SRPs, suggesting thicker and/or denser membranes in LRPs. The degree of membrane compacity affects rigidity, influences biomolecular interactions, and might impact natural rubber coagulation. These results provide additional insights into colloidal behavior of NR for more efficient industrial applications.
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Chaussard, F., Vieillard, T., Billard, F., Faucher, O., Hartmann, J. - M., Boulet, C., & Lavorel, B. (2015). Dissipation of post-pulse laser-induced alignment of CO2 through collisions with Ar. J. Raman Spectrosc., 46(8), 691–694.
Résumé: In this paper, laser-induced field-free alignment of CO2 in mixtures with Ar is investigated under dissipative conditions (up to 15 bars) at room temperature. The degree of alignment is temporally monitored by a polarization spectroscopy technique, where a weak probe pulse measures the transient birefringence resulting from the alignment. The data are analyzed with a quantum mechanical density matrix formalism using properly J-dependent and M-dependent state-to-state transfer rates, which was previously successfully tested on pure CO2 and CO2–He mixtures. The same consistency is obtained between experiments and calculations, in particular the decay times of both the transient revivals and the permanent component of the alignment are accurately predicted by the model.
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Chiaravalloti, F., Dujardin, G. & Riedel, R. (2015). Atomic scale control of hexaphenyl molecules manipulation along functionalized ultra-thin insulating layer on the Si(100) surface at low temperature (9 K). JOURNAL OF PHYSICS-CONDENSED MATTER, 27(5), 054006.
Résumé: Ultra-thin CaF2 layers are grown on the Si(100) surface by using a Knudsen cell evaporator. These epitaxial structures are studied with a low temperature (9 K) scanning tunneling microscope and used to electronically decouple hexaphenyl molecules from the Si surface. We show that the ultra-thin CaF2 layers exhibit stripe structures oriented perpendicularly to the silicon dimer rows and have a surface gap of 3.8 eV. The ultra-thin semi-insulating layers are also shown to be functionalized, since 80 % of the hexaphenyl molecules adsorbed on these structures self-orients along the stripes. Numerical simulations using time-dependent density functional theory allow comparison of computed orbitals of the hexaphenyl molecule with experimental data. Finally, we show that the hexaphenyl molecules can be manipulated along or across the stripes, enabling the molecules to be arranged precisely on the insulating surface.
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De Wit, R., Gautret, P., Bettarel, Y., Roques, C., Marliere, C., Ramonda, M., Thanh, T. N., Quang, H. T., & Bouvier, T. (2015). Viruses Occur Incorporated in Biogenic High-Mg Calcite from Hypersaline Microbial Mats. Plos One, 10(6), e0130552.
Résumé: Using three different microscopy techniques (epifluorescence, electronic and atomic force microscopy), we showed that high-Mg calcite grains in calcifying microbial mats from the hypersaline lake “La Salada de Chiprana”, Spain, contain viruses with a diameter of 50-80 nm. Energy-dispersive X-ray spectrometer analysis revealed that they contain nitrogen and phosphorus in a molar ratio of similar to 9, which is typical for viruses. Nucleic acid staining revealed that they contain DNA or RNA. As characteristic for hypersaline environments, the concentrations of free and attached viruses were high (>10(10) viruses per g of mat). In addition, we showed that acid treatment (dissolution of calcite) resulted in release of viruses into suspension and estimated that there were similar to 15 x 109 viruses per g of calcite. We suggest that virus-mineral interactions are one of the possible ways for the formation of nano-sized structures often described as “nanobacteria” and that viruses may play a role in initiating calcification.
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Depauw, A., Kumar, N., Ha-Thi, M. - H., & Leray, I. (2015). Calixarene-Based Fluorescent Sensors for Cesium Cations Containing BODIPY Fluorophore. The Journal of Physical Chemistry A, 119(23), 6065–6073.
Résumé: New fluorescent molecular sensors based on a calix[4]arene biscrown-6 ether as coordination site and BODIPY derivative as signaling unit were synthesized, and their photophysical properties were characterized. The complexation properties of these sensors with potassium and cesium cations were investigated using both steady-state and time-resolved fluorescence methods. The studies show that the sensitivity with cations depends upon the position of substituted coordination site on the BODIPY core. The complexation with cations does not have much effect on the absorption and emission wavelength when the coordination site (calix[4]arene biscrown-6 ether) is introduced at the meso position of the BODIPY core. In contrast, the same calix[4]arene biscrown-6 ether attached via a styryl linker to the α-position of BODIPY core leads to a sensitive sensor for alkali cations thanks to the better conjugation between the coordination site and the BODIPY core. The complexation of cations induces a hypsochromic shift of the absorption and emission maximums due to the diminution of donor character of the oxygen atoms in the coordination site. The stability constants of complexes with potassium and cesium ion were measured.
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Douin, S., Gronowski, M., Lamarre, N., Phung, V. - T., Boyé-Péronne, S., Crépin, C., & and Kołos, R. (2015). Cavity Ring Down Spectroscopy Measurements for High-Overtone Vibrational Bands of HC3N. Journal of Physical Chemistry A, 119(36), 9494–9505.
Résumé: Overtone (5ν1 and 6ν1) and combination (4ν1+ν3 and 4ν1+ν2) vibrational bands of gaseous HC3N, located in the visible range (14 600-15 800 cm-1 and 17 400-18 600 cm-1), were investigated by cavity ring-down absorption spectroscopy. The 5ν1+ν3 and 5ν1+ν2 combinations as well as the 6ν1+ν5-ν5 hot overtone band have also been identified, based on previous overtone assignments. Absolute integrated intensity values and the ensuing oscillator strengths have been measured here for the first time; f –values are typically confined between 4×10-12 and 7×10-11. For the even weaker 5ν1+ν2 combination band, the oscillator strength was estimated as 9×10-13.
The values concerning CH-stretch overtones (nν1) are similar to those found in the literature for HCN and C2H2, the molecules with sp-hybridized carbon atoms. Data presented here may prove useful for studying the photochemistry triggered with visible or near-IR radiation within the atmospheres of certain Solar System bodies, including Titan.
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El-Daher, M. T., Hangen, E., Bruyere, J., Poizat, G., Al-Ramahi, I., Pardo, R., Bourg, N., Souquere, S., Mayet, C., Pierron, G., Leveque-Fort, S., Botas, J., Humbert, S., & Saudou, F. (2015). Huntingtin proteolysis releases non-polyQ fragments that cause toxicity through dynamin 1 dysregulation. Embo Journal, 34(17), 2255–2271.
Résumé: Cleavage of mutant huntingtin (HTT) is an essential process in Huntington's disease (HD), an inherited neurodegenerative disorder. Cleavage generates N-ter fragments that contain the polyQ stretch and whose nuclear toxicity is well established. However, the functional defects induced by cleavage of full-length HTT remain elusive. Moreover, the contribution of non-polyQ C-terminal fragments is unknown. Using time- and site-specific control of full-length HTT proteolysis, we show that specific cleavages are required to disrupt intramolecular interactions within HTT and to cause toxicity in cells and flies. Surprisingly, in addition to the canonical pathogenic N-ter fragments, the C-ter fragments generated, that do not contain the polyQ stretch, induced toxicity via dilation of the endoplasmic reticulum (ER) and increased ER stress. C-ter HTT bound to dynamin 1 and subsequently impaired its activity at ER membranes. Our findings support a role for HTT on dynamin 1 function and ER homoeostasis. Proteolysis-induced alteration of this function may be relevant to disease.
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Esteban, R., Aguirregabiria, G., Borisov, A. G., Wang, Y. M., Nordlander, P., Bryant, G. W., & Aizpurua, J. (2015). The Morphology of Narrow Gaps Modifies the Plasmonic Response. ACS Photonics, 2(2), 295–305.
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Esteban, R., Zugarramurdi, A., Zhang, P., Nordlander, P., Garcia-Vidal, F. J., Borisov, A. G., & Aizpurua, J. (2015). A classical treatment of optical tunneling in plasmonic gaps: extending the quantum corrected model to practical situations. Faraday Discuss., 178, 151–183.
Résumé: The optical response of plasmonic nanogaps is challenging to address when the separation between the two nanoparticles forming the gap is reduced to a few nanometers or even subnanometer distances. We have compared results of the plasmon response within different levels of approximation, and identified a classical local regime, a nonlocal regime and a quantum regime of interaction. For separations of a few Angstroms, in the quantum regime, optical tunneling can occur, strongly modifying the optics of the nanogap. We have considered a classical effective model, so called Quantum Corrected Model (QCM), that has been introduced to correctly describe the main features of optical transport in plasmonic nanogaps. The basics of this model are explained in detail, and its implementation is extended to include nonlocal effects and address practical situations involving different materials and temperatures of operation.
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Falvo, C., Daniault, L., Vieille, T., Kemlin, V., Lambry, J. - C., Meier, C., Vos, M. H., Bonvalet, A., & and Joffre, M. (2015). Ultrafast Dynamics of Carboxy-Hemoglobin: Two-Dimensional Infrared Spectroscopy: Experiments and Simulations. J. Phys. Chem. Lett., 6, 2216–2222.
Résumé: This Letter presents a comparison between experimental and simulated 2D mid-infrared spectra of carboxy-hemoglobin in the spectral region of the carbon monoxide stretching mode. The simulations rely on a fluctuating potential energy surface that includes both the effect of heme and the protein surroundings computed from molecular dynamics simulations. A very good agreement between theory and experiment is obtained with no adjustable parameters. The simulations show that the effect of the distal histidine through the hydrogen bond is strong and is directly responsible for the slow decay of the frequency-frequency correlation function on a 10 ps time scale. This study confirms that fluctuations in carboxy-hemoglobin are more inhomogeneous than those in the more frequently studied carboxy-myoglobin. The comparison between simulations and experiments brings valuable information on the complex relation between protein structure and spectral diffusion.
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Feraud, G., Broquier, M., Dedonder, C., Jouvet, C., Gregoire, G., & Soorkia, S. (2015). Excited State Dynamics of Protonated Phenylalanine and Tyrosine: Photo-Induced Reactions Following Electronic Excitation. J Phys Chem A, 119(23), 5914–5924.
Résumé: The electronic spectroscopy and the electronic excited state properties of cold protonated phenylalanine and protonated tyrosine have been revisited on a large spectral domain and interpreted by comparison with ab initio calculations. The protonated species are stored in a cryogenically cooled Paul trap, maintained at approximately 10 K, and the parent and all the photofragment ions are mass-analyzed in a time-of-flight mass spectrometer, which allows detecting the ionic species with an improved mass resolution compared to what is routinely achieved with a quadrupole mass spectrometer. These new results emphasize the competition around the band origin between two proton transfer reactions from the ammonium group toward either the aromatic chromophore or the carboxylic acid group. These reactions are initiated by the coupling of the locally excited pipi* state with higher charge transfer states, the positions and coupling of which depend on the conformation of the protonated molecules. Each of these reaction processes gives rise to specific fragmentation channels that supports the conformer selectivity observed in the photofragmentation spectra of protonated tyrosine and phenylalanine.
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Ferrand, L., Soorkia, S., Gregoire, G., Broquier, M., Soep, B., & Shafizadeh, N. (2015). Bonding of heme FeIIIwith dioxygen: Observation and characterization of an incipient bond. Phys. Chem. Chem. Phys., 17, 25693–25699.
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Finkelstein-Shapiro, D., Urdaneta, I., Calatayud, M., Atabek, O., Mujica, V., & Keller, A. (2015). Fano-Liouville Spectral Signatures in Open Quantum Systems. Physical Review Letters, 115, 113006.
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Fraix, A., Kandoth, N., Gref, R., & Sortino, S. (2015). A Multicomponent Gel for Nitric Oxide Photorelease with Fluorescence Reporting. Asian Journal Of Organic Chemistry, 4(3), 256–261.
Résumé: An engineered hydrogel platform has been developed, in the absence of any toxic solvents or reagents, by the supramolecular self-assembly of three different components: a poly--cyclodextrin polymer, a hydrophobically modified dextran, and a photoactivatable bichromophoric molecular conjugate designed to photorelease nitric oxide (NO) with a fluorescent reporting function. The multivalent character of the interactions between the all components and the poor solubility of the conjugate in aqueous medium ensure the stability of the hydrogel and the lack of leaching of the photoactive cargo from the gel network under physiological conditions, even in the absence of protective coating agents. The photochemical properties of the molecular conjugate are retained in the supramolecular matrix, as demonstrated by the remote-controlled release of NO upon visible light excitation simultaneously to the activation of a fluorescent reporting function, which allows easy monitoring of the photoreleased NO.
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Garcia, G. A., Gans, B., Tanga, X., Ward, M., Batut, S., Nahon, L., Fittschen, C., & Loison, J. - C. (2015). Threshold photoelectron spectroscopy of the imidogen radical. Journal of Electron Spectroscopy and Related Phenomena, 203, 25–30.
Résumé: We present the threshold photoelectron spectroscopy of the imidogen radical (NH) recorded in the photon energy region up to 1 eV above its first ionization threshold. The radical was produced by reaction of NH3 and F in a microwave discharge flow-tube and photoionized using vacuum ultraviolet (VUV) synchrotron radiation. A double imaging coincidence spectrometer was used to record mass-selected spectra and avoid contributions from the byproducts present in the reactor and background gas. The energy region includes the ground X+2Π and first electronically excited a+4Σ− states of NH+. Strong adiabatic transitions and weak vibrational progressions up to v+ = 2 are observed for both electronic states. The rotational profile seen in the origin band has been modeled using existing neutral and cationic spectroscopic constants leading to a precise determination of the adiabatic ionization energy at 13.480 ± 0.002 eV.
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Gauyacq, J. - P., & Lorente, N. (2015). Decoherence-governed magnetic-moment dynamics of supported atomic objects. J. Phys. Condens. Matter., 27(45), 455301.
Résumé: Due to the quantum evolution of molecular magnetic moments, the magnetic state of nanomagnets can suffer spontaneous changes. This process can be completely quenched by environment-induced decoherence. However, we show that for typical small supported atomic objects, the substrate-induced decoherence does change the magnetic-moment evolution but does not quell it. To be specific and to compare with experiment, we analyze the spontaneous switching between two equivalent magnetization states of atomic structures formed by Fe on Cu2N/Cu (1 0 0), measured by Loth et al (2012 Science 335 196-9). Due to the substrate-induced decoherence, the Rabi oscillations proper to quantum tunneling between magnetic states are replaced by an irreversible decay of long characteristic times leading to the observed stochastic magnetization switching. We show that the corresponding switching rates are small, rapidly decreasing with system's size, with a 1/T thermal behavior and in good agreement with experiments. Quantum tunneling is recovered as the switching mechanism at extremely low temperatures below the muK range for a six-Fe-atom system and exponentially lower for larger atomic systems. The unexpected conclusion of this work is that experiments could detect the switching of these supported atomic systems because their magnetization evolution is somewhere between complete decoherence-induced stability and unobservably fast quantum-tunneling switching.
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Goubet, M., Soulard, P., Pirali, O., Asselin, P., Réal, F., Gruet, S., Huet, T. R., & Roy, P. and G., R. (2015). Standard free energy of the equilibrium between the trans-monomer and the cyclic-dimer of acetic acid in the gas phase from infrared spectroscopy. Physical Chemistry Chemical Physics, 17(11), 7477–7488.
Résumé: Survey jet-cooled spectra of acetic acid have been recorded in the infrared region (200-4000 cm(-1)) over a wide range of expansion conditions. From the variations of the relative intensities of the signals, vibrational transitions have been assigned unambiguously to the trans-monomer and cyclic-dimer. The IR-active fundamental frequencies have been determined at the instrumental accuracy of 0.5 cm(-1). This analysis of the jet-cooled spectra supported by electronic structure calculations permitted us to characterize the trans-monomer/cyclic-dimer equilibrium. From static cell spectra at 298 K, variations of the molar fractions ratio as a function of the total pressure were used to estimate the equilibrium constant and the Gibbs free energy of dimerization at 298 K. The very good agreement with the literature data shows that the present method is able to produce, from a single study, a free energy value as reliable as the one obtained from a large collection of data. In addition, the semi-empirical free energy value was used to estimate the accuracy of electronic structure calculations and in turn the accuracy of the derived useful information such as the dissociation energy of the complex (i.e. the strength of the hydrogen bonds) or the relative energies within the conformational landscape.
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Guilbaud, O., Cojocaru, G. V., Li, L., Delmas, O., Ungureanu, R. G., Banici, R. A., Kazamias, S., Cassou, K., Neveu, O., Demailly, J., Baynard, E., Pittman, M., Le Marec, A., Klisnick, A., Zeitoun, P., Ursescu, D., & Ros, D. (2015). Gain dynamics in quickly ionized plasma for seeded operated soft x-ray lasers. Optics Letters, 40(20), 4775–4778.
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He, X., Wang, W., Li, S., Liu, Y., Zheng, W., Shi, Q., & Luo, X. (2015). Experimental and theoretical analysis of ZnO/Au/ZnO transparent conducting thin films. Vacuum, 120, 17–21.
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He, X., Wang, W., Li, S., Wang, Q., Zheng, W., Shi, Q., & Liu, Y. (2015). High Efficiency Electron Transfer Layer based on Ag-Al Co-Doped ZnS in Organic Lighting Emission Devices. ECS SOLID STATE LETTERS, 4(2), R10–R12.
Résumé: Electron transmission improvement in organic light-emitting devices with Ag-Al co-doped ZnS has been demonstrated. The electroluminescence (EL) of device with co-doped ZnS electron transfer layer (ETL) is more than that of devices without ETL and the co-doped ZnS ETL device performs higher EL compared to pure ZnS ETL device. The using of co-doped ZnS can reduce the thickness of ETL from 40 nm to 8 nm and performs comparable efficiency and higher EL. According to the PL spectra studies and current density-voltage characters, the improved electron transmission is attributed to the introduction of impurity energy level and the increased concentration of electron. (C) 2014 The Electrochemical Society. All rights reserved.
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He, X., Wang, W., Li, S., Wang, Q., Zheng, W., Shi, Q., & Liu, Y. (2015). Localized Surface Plasmon-Enhanced Electroluminescence in OLEDs by Self-Assembly Ag Nanoparticle Film. Nanoscale Res Lett, 10(1), 468.
Résumé: We fabricated Ag nanoparticle (NP) film in organic light emission diodes (OLEDs), and a 23 times increase in electroluminescence (EL) at 518 nm was probed by time-resolved EL measurement. The luminance and relative external quantum efficiency (REQE) were increased by 5.4 and 3.7 times, respectively. There comes a new energy transport way that localized surface plasmons (LSPs) would absorb energy that corresponds to the electron-hole pair before recombination, promoting the formation of electron-hole pair and exciting local surface plasmon resonance (LSPR). The extended lifetime of Alq3 indicates the existence of strong interaction between LSPR and exciton, which decreases the nonradiative decay rate of OLEDs.
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Hernandez, F. J., Capello, M. C., Naito, A., Manita, S., Tsukada, K., Miyazaki, M., Fujii, M., Broquier, M., Gregoire, G., Dedonder-Lardeux, C., Jouvet, C., & Pino, G. A. (2015). Trapped Hydronium Radical Produced by Ultraviolet Excitation of Substituted Aromatic Molecule. J Phys Chem A, 119(51), 12730–12735.
Résumé: The gas phase structure and excited state dynamics of o-aminophenol-H2O complex have been investigated using REMPI, IR-UV hole-burning spectroscopy, and pump-probe experiments with picoseconds laser pulses. The IR-UV spectroscopy indicates that the isomer responsible for the excitation spectrum corresponds to an orientation of the OH bond away from the NH2 group. The water molecule acts as H-bond acceptor of the OH group of the chromophore. The complexation of o-aminophenol with one water molecule induced an enhancement in the excited state lifetime on the band origin. The variation of the excited state lifetime of the complex with the excess energy from 1.4 +/- 0.1 ns for the 0-0 band to 0.24 +/- 0.3 ns for the band at 0-0 + 120 cm(-1) is very similar to the variation observed in the phenol-NH3 system. This experimental result suggests that the excited state hydrogen transfer reaction is the dominant channel for the non radiative pathway. Indeed, excited state ab initio calculations demonstrate that H transfer leading to the formation of the H3O(*) radical within the complex is the main reactive pathway.
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Houplin, J., Amiaud, L., Dablemont, C., & Lafosse, A. (2015). DOS and electron attachment effects in the electron-induced vibrational excitation of terphenylthiol SAMs. Phys Chem Chem Phys, 17(45), 30721–30728.
Résumé: Low energy electron scattering on terphenylthiol (TPT, HS-(C6H4)2-C6H5) self-assembled monolayers (SAMs) deposited onto gold was investigated using high resolution electron energy loss spectroscopy (HREELS) by recording specular elastic and inelastic excitation functions. The electron elastic reflectivity could be directly compared to the sample density-of-states (DOS) above vacuum level. A high reflectivity region was observed in the range 7.2-8.6 eV. Inelastic excitation functions were studied to get insights into the mechanisms involved in the excitation of a selection of vibrational modes (dipolar and impact scattering). In particular, a resonant mechanism was observed in the excitation of the stretching mode nu(CC) at 196 meV. The purely resonant contribution to the electron-induced excitation of the stretching modes nu(CH) (379 meV) could be extracted from the overtone excitation. It is located at 7.2 eV above the vacuum level and is characterized by a width of 3.4 eV.
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Houplin, J., Amiaud, L., Sedzik, T., Dablemont, C., Teillet-Billy, D., Rougeau, N., & Lafosse, A. (2015). A combined DFT/HREELS study of the vibrational modes of terphenylthiol SAMs. Eur. Phys. J. D, 69(9), 9 pp.
Résumé: Self-assembled monolayers of p-terphenylthiol (TPT, HS-(C6H4)(2)-C6H5) deposited onto gold can serve as model systems for aromatic lithography resists. Such thin molecular films are suitably probed using high resolution electron energy loss spectroscopy, due to its high surface sensitivity. Extended energy loss spectra were measured at different probing energies. The TPT monolayer overlapping.(CH) stretching modes could be modelled by a single effective anharmonic oscillator sustained by a Morse potential energy curve, thanks to the resonant excitation of the associated overtone series at 6 eV. A remarkably good agreement was obtained between the TPT monolayer energy loss spectrum and the computer-simulated infrared vibrational spectrum of the isolated TPT molecule. Density Functional Theory calculations for TPT, fully deuterated TPT and benzenethiol isolated molecules were performed with the exchange correlation functional B3LYP and a dispersion correction, using a triple zeta+ polarisation basis set. By comparing the vibrational patterns obtained for these parent systems, (re-) assignments of all the features observed in the TPT self-assembled monolayer energy loss spectrum are discussed. The obtained vibrational assignments can be confidently transposed to other related systems, such as benzenethiol and biphenyl self-assembled monolayers.
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Houplin, J., Dablemont, C., Sala, L., Lafosse, A., & Amiaud, L. (2015). Electron Processing at 50 eV of Terphenylthiol Self-Assembled Monolayers: Contributions of Primary and Secondary Electrons. Langmuir, 31(50), 13528–13534.
Résumé: Aromatic self-assembled monolayers (SAMs) can serve as platforms for development of supramolecular assemblies driven by surface templates. For many applications, electron processing is used to locally reinforce the layer. To achieve better control of the irradiation step, chemical transformations induced by electron impact at 50 eV of terphenylthiol SAMs are studied, with these SAMs serving as model aromatic SAMs. High-resolution electron energy loss spectroscopy (HREELS) and electron-stimulated desorption (ESD) of neutral fragment measurements are combined to investigate electron-induced chemical transformation of the layer. The decrease of the CH stretching HREELS signature is mainly attributed to dehydrogenation, without a noticeable hybridization change of the hydrogenated carbon centers. Its evolution as a function of the irradiation dose gives an estimate of the effective hydrogen content loss cross-section, sigma = 2.7-4.7 x 10(-17) cm(2). Electron impact ionization is the major primary mechanism involved, with the impact electronic excitation contributing only marginally. Therefore, special attention is given to the contribution of the low-energy secondary electrons to the induced chemistry. The effective cross-section related to dissociative secondary electron attachment at 6 eV is estimated to be 1 order of magnitude smaller. The 1 eV electrons do not induce significant chemical modification for a 2.5 mC cm(-2) dose, excluding their contribution.
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Jacovella, U., Holland, D. M. P., Boyé-Péronne, S., Gans, B., Joyeux, D., Archer, L. E., de Oliveira, N., Nahon, L., Lucchese, R. R., & Xu, H. and P., S. T. (2015). High-resolution vacuum-ultraviolet photoabsorption spectra of 1-butyne and 2-butyne. J. Chem. Phys., 143, 034304.
Résumé: The absolute photoabsorption cross section of propyne was recorded between 62 000 and 88 000 cm−1 by using the vacuum-ultraviolet, Fourier-transform spectrometer at the Synchrotron Soleil. This cross section spans the region including the lowest Rydberg bands and extends above the Franck-Condon envelope for ionization to the ground electronic state of the propyne cation, ˜X+.
Room-temperature spectra were recorded in a flowing cell at 0.9 cm−1 resolution, and jet-cooled spectra were recorded at 1.8 cm−1 resolution and a rotational temperature of ∼100 K. The reduced widths of the rotational band envelopes in the latter spectra reveal new structure and simplify a number of assignments. Although nf Rydberg series have not been assigned previously in the photoabsorption spectrum of propyne, arguments are presented for their potential importance,
and the assignment of one nf series is proposed. As expected from previous photoelectron spectra, Rydberg series are also observed above the adiabatic ionization threshold that converge to the v3 + = 1 and 2 levels of the C≡C stretching vibration.
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Jacovella, U., Gans, B., & Merkt, F. (2015). Internal rotation, spin–orbit coupling, and low-frequency vibrations in the ground state of CH3–CC–CH+3 and CD3–CC–CD+3. Molecular Physics, 113(15-16), 2115–2124.
Résumé: Pulsed-field-ionisation zero-kinetic-energy (PFI-ZEKE) photoelectron spectra of 2-butyne (CH3–CC–CH3) and its fully deuterated isotopomer have been recorded in the region of the origin band of the ionising transition. The spectral congestion originating from the combined effects of the internal rotation of the methyl groups, the spin–orbit coupling, and the Jahn–Teller effect prevented the full resolution of the rotational structure of the photoelectron spectra. A tentative analysis of the rotational branch structure of the photoelectron spectra using rovibronic photoionisation selection rules derived in the permutation–inversion spin double group G36(M2) suggests a splitting of ∼10.5 cm−1 between the two spin–orbit components E3/2 and E1/2 of the 2 E1 ground state and an almost free internal rotation of the methyl groups in the cations. Assignments are proposed for several low-lying vibrational levels of the cations.
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Jacovella, U., Holland, D. M. P., Boyé-Péronne, S., Gans, B., de Oliveira, N., Ito, K., Joyeux, D., Archer, L. E., Lucchese, R. R., Xu, H., & Pratt, S. T. (2015). A Near-Threshold Shape Resonance in the Valence-Shell Photoabsorption of Linear Alkynes. The Journal of Physical Chemistry A, 119(50), 12339–12348.
Résumé: The room-temperature photoabsorption spectra of a number of linear alkynes with internal triple bonds (e.g., 2-butyne, 2-pentyne, and 2- and 3-hexyne) show similar resonances just above the lowest ionization threshold of the neutral molecules. These features result in a substantial enhancement of the photoabsorption cross sections relative to the cross sections of alkynes with terminal triple bonds (e.g., propyne, 1-butyne, 1-pentyne, ...). Based on earlier work on 2-butyne [Xu et al., J. Chem. Phys. 2012, 136, 154303], these features are assigned to excitation from the neutral highest occupied molecular orbital (HOMO) to a shape resonance with g (l = 4) character and approximate π symmetry. This generic behavior results from the similarity of the HOMOs in all internal alkynes, as well as the similarity of the corresponding gπ virtual orbital in the continuum. Theoretical calculations of the absorption spectrum above the ionization threshold for the 2- and 3-alkynes show the presence of a shape resonance when the coupling between the two degenerate or nearly degenerate π channels is included, with a dominant contribution from l = 4. These calculations thus confirm the qualitative arguments for the importance of the l = 4 continuum near threshold for internal alkynes, which should also apply to other linear internal alkynes and alkynyl radicals. The 1-alkynes do not have such high partial waves present in the shape resonance. The lower l partial waves in these systems are consistent with the broader features observed in the corresponding spectra.
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Jaouadi, A., Telmini, M., & Charron, E. (2015). Bose-Einstein condensation with a finite number of particles in a power-law trap. Phys. Rev. A, 92(1), 017602.
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Jia, J., Kara, A., Pasquali, L., Bendounan, A., Sirotti, F., & Esaulov, V. A. (2015). On sulfur core level binding energies in thiol self-assembly and alternative adsorption sites: An experimental and theoretical study. J.Phys.Chem C, 143(10), 104702.
Résumé: Characteristic core level binding energies (CLBEs) are regularly used to infer the modes of molecular adsorption: orientation, organization, and dissociation processes. Here, we focus on a largely debated situation regarding CLBEs in the case of chalcogen atom bearing molecules. For a thiol, this concerns the case when the CLBE of a thiolate sulfur at an adsorption site can be interpreted alternatively as due to atomic adsorption of a S atom, resulting from dissociation. Results of an investigation of the characteristics of thiol self-assembled monolayers (SAMs) obtained by vacuum evaporative adsorption are presented along with core level binding energy calculations. Thiol ended SAMs of 1,4-benzenedimethanethiol (BDMT) obtained by evaporation on Au display an unconventional CLBE structure at about 161.25 eV, which is close to a known CLBE of a S atom on Au.Adsorption and CLBE calculations for sulfur atoms and BDMT molecules are reported and allow delineating trends as a function of chemisorption on hollow, bridge, and atop sites and including the presence of adatoms. These calculations suggest that the 161.25 eV peak is due to an alternative adsorption site, which could be associated to an atop configuration. Therefore, this may be an alternative interpretation, different from the one involving the adsorption of atomic sulfur resulting from the dissociation process of the S–C bond. Calculated differences in S(2p) CLBEs for free BDMT molecules, SH group sulfur on top of the SAM, and disulfide are also reported to clarify possible errors in assignments.
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Ketterer A., Keller A., Coudreau T., & Milman P. (2015). Testing the Clauser-Horne-Shimony-Holt inequality using observables with arbitrary spectrum. Phys. Rev. A, 91, 012106.
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Kisiel, Z., Martin-Drumel, M. - A., & Pirali, O. (2015). Lowest vibrational states of acrylonitrile from microwave and synchrotron radiation spectra. Spectroscopy with Synchrotron Radiation, 315, 83–91.
Résumé: The high resolution Fourier-transform spectrum of acrylonitrile covering the 40–700cm−1 spectral region was recorded at the AILES infrared beamline of the SOLEIL synchrotron. The spectrum allowed assignment of vibration–rotation transitions in four different fundamental bands, five hot bands, one overtone band, as well as of some pure rotational transitions. The new infrared data and previous measurements made with microwave techniques have been combined into a single global fit encompassing over 31000 measured transitions. Precise vibrational term values have been determined for the eight lowest excited vibrational states, including ν11=228.299930(4), ν15=332.678207(4), ν10=560.716701(5), and ν14=681.793862(13)cm−1. The new values are compared with those obtained previously entirely on the basis of rotational perturbations. Several anharmonicity coefficients are determined and compared with abinitio anharmonic force field calculations. The assignment of the ν10 mode is also clarified.
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Labaigt, G., Jorge, A., Illescas, C., Béroff, K., Dubois, A., Pons, B., & Chabot, M. (2015). Electron capture and ionization processes in high-velocity C+ n , C – Ar and He collisions. J. Phys. B, 48, 075201.
Résumé: Single and double electron capture as well as projectile single and multiple
ionization processes in 125 keV/u C+n- He (n=1-5) and C+n-Ar (n=1,2,4) collisions
have been studied experimentally and theoretically. Helium target single and double
ionization cross sections are also reported for C+n- He (n=1,4) collisions in the 100-400 keV/u impact energy domain. These results are compared with predictions from the Independent Atom and Electron (IAE) model developed to describe cluster-atom collisions. The ion/atom-atom probabilities required for the IAE simulations have been determined by Classical Trajectory Monte Carlo (CTMC) and SemiClassical AtomicOrbital Close-Coupling (SCAOCC) calculations for the Ar and He targets, respectively.
For comparison electron capture cross sections were also measured in C – He and Ar
collisions. In general the agreement between experiment and IAE calculations has been found rather good with the exception of double electron capture leading to anionic Cn- species.
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Ladaviere, C., & Gref, R. (2015). Toward an optimized treatment of intracellular bacterial infections: input of nanoparticulate drug delivery systems. Nanomedicine, 10(19), 3033–3055.
Résumé: Intracellular pathogenic bacteria can lead to some of the most life-threatening infections. By evolving a number of ingenious mechanisms, these bacteria have the ability to invade, colonize and survive in the host cells in active or latent forms over prolonged period of time. A variety of nanoparticulate systems have been developed to optimize the delivery of antibiotics. Main advantages of nanoparticulate systems as compared with free drugs are an efficient drug encapsulation, protection from inactivation, targeting infection sites and the possibility to deliver drugs by overcoming cellular barriers. Nevertheless, despite the great progresses in treating intracellular infections using nanoparticulate carriers, some challenges still remain, such as targeting cellular subcompartments with bacteria and delivering synergistic drug combinations. Engineered nanoparticles should allow controlling drug release both inside cells and within the extracellular space before reaching the target cells.
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Lamarre, N., Falvo, C., Alcaraz, C., Cunha de Miranda, B., Douin, S., Flütsch, A., Romanzin, C., Guillemin, J. - C., & Boyé-Péronne, S., Gans, B. (2015). Photoionization spectroscopy of CH3C3N in the vacuum-ultraviolet range. Journal of Molecular Spectroscopy, 315, 206–216.
Résumé: Using vacuum-ultraviolet (VUV) synchrotron radiation, threshold and dissociative photoionization of cyanopropyne (CH3C3N) in the gas phase have been studied from 86000 cm-1 up to 180000 cm-1 by recording Threshold-PhotoElectron Spectrum (TPES)
and PhotoIon Yield (PIY). Ionization energies of the four lowest electronic states X+ 2E, A+ 2A1, B+ 2E and C+ of CH3C3N+ are derived from the TPES with a better accuracy than previously reported. The adiabatic ionization potential of CH3C3N is measured as 86872 +/- 20 cm-1. A description of the vibrational structure of these states is proposed leading to the first determination of the vibrational frequencies for most modes. The vibrational assignments of the X+ state are supported by density functional theory calculations. In addition, dissociative photoionization spectra have been recorded for several cationic fragments in the range 12- 15.5 eV (96790-125000 cm-1) and they bring new information on the photophysics of CH3C3N+. Threshold energies for the cationic dissociative channels leading to CH2C3N+, CHC3N+, HC3H+, HCNH+ and CH+3 have been measured for the first time and are compared with quantum chemical calculations.
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Lamarre, N., Gans, B., Alcaraz, C., Cunha de Miranda, B., Guillemin, J. - C., Broquier, M., Liévin, J., & Boyé-Péronne, S. (2015). Vibronic structure of the 2Πu ground electronic state of dicyanoacetylene cation revisited by PFI-ZEKE photoelectron spectroscopy and ab initio calculations. Molecular Physics, 113(24), 3946–3954.
Résumé: The X+ 2Piu ← X 1Sigma+ g transition of dicyanoacetylene has been recorded for the first time using Pulsed-Field-Ionization ZEro-Kinetic Energy (PFI-ZEKE) photoelectron spectroscopy.
The analysis of the photoelectron spectrum allowed an accurate determination of the adiabatic ionization potential of C4N2 (Ei, ad./hc = 95479±2 cm−1) and a description of the vibrational structure of the electronic ground state of the cation which is affected by Renner-Teller effect and spin-orbit interaction. The spin-orbit coupling constant was measured as −52 ± 2 cm−1.
These results are supported by ab initio calculations performed at the Complete Active Space Self Consistent Field and Second order Perturbation Theory (CASSCF and CASPT2) levels of theory, with extrapolation to the complete basis set limit.
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Le Marec A., K. M., Nejdl J., Tissandier F., Meng L., Guilbaud O., Calisti A., and Klisnick A. (2015). Measurement of a sub-picosecond coherence time in a quasi-steady state XUV laser. Phys. Rev. A, 92, 033852.
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Lefebvre, R. (2015). Factorized molecular wave functions: Analysis of the nuclear factor. J Chem Phys, 142(21), 214105.
Résumé: The exact factorization of molecular wave functions leads to nuclear factors which should be nodeless functions. We reconsider the case of vibrational perturbations in a diatomic species, a situation usually treated by combining Born-Oppenheimer products. It was shown [R. Lefebvre, J. Chem. Phys. 142, 074106 (2015)] that it is possible to derive, from the solutions of coupled equations, the form of the factorized function. By increasing artificially the interstate coupling in the usual approach, the adiabatic regime can be reached, whereby the wave function can be reduced to a single product. The nuclear factor of this product is determined by the lowest of the two potentials obtained by diagonalization of the potential matrix. By comparison with the nuclear wave function of the factorized scheme, it is shown that by a simple rectification, an agreement is obtained between the modified nodeless function and that of the adiabatic scheme.
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Lefebvre, R. (2015). Perturbations in vibrational diatomic spectra: factorization of the molecular wave function. J Chem Phys, 142(7), 074106.
Résumé: The coupling between two electronic states of a diatomic molecule may lead to an erratic behaviour of the associated vibrational energies. An example is the homogeneous coupling between the valence b' state and the Rydberg c' state of the N2 molecule, both of symmetry (1)Sigmau (+). The standard treatment of such a situation is to write the wave function as a sum of two Born-Oppenheimer products. It has recently been argued [L. S. Cederbaum, J. Chem. Phys. 138, 224110 (2013); N. I. Gidopoulos and E. K. U. Gross, Philos. Trans. R. Soc., A 372, 20130059 (2014)] that even in such a case the wave function should be representable as a single product, with an electronic factor depending parametrically on nuclear positions and a nuclear factor. We setup such a representation in the case of the perturbations in the N2 molecule.
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Lefebvre-Brion, H., & Majumder, M. (2015). Isotopic dependence of the predissociations of the E(1)Pi state of CO. J Chem Phys, 142(16), 164306.
Résumé: The predissociations of the E(1)Pi state of CO are again studied. They include both the background predissociation attributed to the continuum of the A(1)Pi state and the accidental predissociation due to the k(3)Pi state. They are calculated using a coupled equations method. The three components of the k state are introduced. These predissociations are studied for different isotopologues and are shown to decrease with increasing reduced mass, in agreement with the experimental results of Ubachs et al. [J. Chem. Phys. 113, 547 (2000)].
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Lin, L., Zapata, M., Xiong, M., Liu, Z., Wang, S., Xu, H., Borisov, A. G., Gu, H., Nordlander, P., Aizpurua, J., & Ye, J. (2015). Nanooptics of Plasmonic Nanomatryoshkas: Shrinking the Size of a Core-Shell Junction to Subnanometer. Nano Lett., 15(10), 6419–6428.
Résumé: Quantum effects in plasmonic systems play an important role in defining the optical response of structures with subnanometer gaps. Electron tunneling across the gaps can occur, altering both the far-field optical response and the near-field confinement and enhancement. In this study, we experimentally and theoretically investigate plasmon coupling in gold “nanomatryoshka” (NM) nanoparticles with different core-shell separations. Plasmon coupling effects between the core and the shell become significant when their separation decreases to 15 nm. When their separation decreases to below 1 nm, the near- and far-field properties can no longer be described by classical approaches but require the inclusion of quantum mechanical effects such as electron transport through the self-assembled monolayer of molecular junction. In addition, surface-enhanced Raman scattering measurements indicate strong electron-transport induced charge transfer across the molecular junction. Our quantum modeling provides an estimate for the AC conductances of molecules in the junction. The insights acquired from this work pave the way for the development of novel quantum plasmonic devices and substrates for surface-enhanced Raman scattering.
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Liu, R., Xian, Z., Zhang, S., Chen, C., Yang, Z., Li, H., Zheng, W., Zhang, G., & Cao, H. (2015). Electrochemical-reduction-assisted assembly of ternary Ag nanoparticles/polyoxometalate/graphene nanohybrids and their activity in the electrocatalysis of oxygen reduction. RSC ADVANCES, 5(91), 74447–74456.
Résumé: The green, facile, electrochemical-reduction-assisted assembly of ternary Ag nanoparticles (NPs)@polyoxometalate (POM)/reduced graphene oxide (rGO) is reported. The POM served as an electrocatalyst and bridging molecule. Characterization using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman and FT-IR spectroscopy analysis, etc., was performed and verified the structure of the prepared nanohybrids of Ag NPs@POM/rGO. The density and size of the Ag NPs on the rGO can be simply tuned by changing the concentration of Ag+. Most importantly, it is interesting to find that the ternary Ag NPs@POM/rGO nanohybrids showed much better electrocatalytic activities towards the oxygen reduction reaction than binary Ag NPs@POM and POM/rGO nanohybrids, and a direct four-electron transfer pathway was observed because of the synergistic effect of the Ag NPs and rGO. The electrocatalytic performance of Ag NPs@POM/rGO depended on the loading amount of Ag NPs, and 30% Ag NPs@POM/rGO showed the best electrocatalytic performance.
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Lozada-Garcia, R., Rojas-Lorenzo, G., Crepin, C., Ryan, M., & McCaffrey, J. G. (2015). Hg-Xe Exciplex Formation in Mixed Xe/Ar Matrices: Molecular Dynamics and Luminescence Study. Journal Of Physical Chemistry A, 119(11), 2307–2317.
Résumé: Luminescence of Hg(P-3(1)) atoms trapped in mixed Ar/Xe matrices containing a small amount of Xe is reported. Broad emission bands, strongly red-shifted from absorption are recorded which are assigned to strong complexes formed between the excited mercury Hg* and xenon atoms. Molecular dynamics calculations are performed on simulated Xe/Ar samples doped with Hg to follow the behavior of Hg* in the mixed rare gas matrices leading to exciplex formation. The role of Xe atoms in the first solvation shell (SS1) around Hg was investigated in detail, revealing the formation of two kinds of triatomic exciplexes; namely, Xe-Hg*-Xe and Ar-Hg*-Xe. The first species exists only when two xenon atoms are present in SS1 with specific geometries allowing the formation of a linear or quasi-linear exciplex. In the other geometries, or in the presence of only one Xe in SS1, a linear Ar-Hg*-Xe exciplex is formed. The two kinds of exciplexes have different emission bands, the most red-shifted being that involving two Xe atoms, whose emission is very close to that observed in pure Xe matrices. Simulations give a direct access to the analysis of the experimental absorption, emission, and excitation spectra, together with the dynamics of exciplexes formation.
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Lupone, S., Damoy, S., Husseen, A., Briand, N., Debiossac, M., Tall, S., & Roncin, P. (2015). A large open ratio, time and position sensitive detector for time of ight measurements in UHV. RSI, 86, 126115.
Résumé: We report on the construction of an UHV compatible 40 mm active diameter detector based on micro channel plates and assembled directly on the feed-throughs of a DN63CF flange. It is based on the charge division technique and uses a standard 2 inch Si wafer as a collector. The front end electronic is placed directly on the air side of the flange allowing excellent immunity to noise and a very good timing signal with reduced ringing. The important aberrations are corrected empirically
providing an absolute positioning accuracy of 500 μm while a 150 μm resolution is measured in the center.
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Marinica, D. C., Zapata, M., Nordlander, P., Kazansky, A. K., M Echenique, P., Aizpurua, J., & Borisov, A. G. (2015). Active quantum plasmonics. Sci. Adv., 1(11), e1501095.
Résumé: The ability of localized surface plasmons to squeeze light and engineer nanoscale electromagnetic fields through electron-photon coupling at dimensions below the wavelength has turned plasmonics into a driving tool in a variety of technological applications, targeting novel and more efficient optoelectronic processes. In this context, the development of active control of plasmon excitations is a major fundamental and practical challenge. We propose a mechanism for fast and active control of the optical response of metallic nanostructures based on exploiting quantum effects in subnanometric plasmonic gaps. By applying an external dc bias across a narrow gap, a substantial change in the tunneling conductance across the junction can be induced at optical frequencies, which modifies the plasmonic resonances of the system in a reversible manner. We demonstrate the feasibility of the concept using time-dependent density functional theory calculations. Thus, along with two-dimensional structures, metal nanoparticle plasmonics can benefit from the reversibility, fast response time, and versatility of an active control strategy based on applied bias. The proposed electrical manipulation of light using quantum plasmonics establishes a new platform for many practical applications in optoelectronics.
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Marliere, C., & Dhahri, S. (2015). An in vivo study of electrical charge distribution on the bacterial cell wall by atomic force microscopy in vibrating force mode. Nanoscale, 7(19), 8843–8857.
Résumé: We report an in vivo electromechanical atomic force microscopy (AFM) study of charge distribution on the cell wall of Gram+ Rhodococcus wratislaviensis bacteria, naturally adherent to a glass substrate, under physiological conditions. The method presented in this paper relies on a detailed study of AFM approach/retract curves giving the variation of the interaction force versus distance between the tip and the sample. In addition to classical height and mechanical (as stiffness) data, mapping of local electrical properties, such as bacterial surface charge, was proved to be feasible at a spatial resolution better than a few tens of nanometers. This innovative method relies on the measurement of the cantilever's surface stress through its deflection far from (>10 nm) the repulsive contact zone: the variations of surface stress come from the modification of electrical surface charge of the cantilever (as in classical electrocapillary measurements) likely stemming from its charging during contact of both the tip and the sample electrical double layers. This method offers an important improvement in local electrical and electrochemical measurements at the solid/liquid interface, particularly in high-molarity electrolytes when compared to techniques focused on the direct use of electrostatic force. It thus opens a new way to directly investigate in situ biological electrical surface processes involved in numerous practical applications and fundamental problems such as bacterial adhesion, biofilm formation, microbial fuel cells, etc.
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Martin-Drumel, M. - A., Mouret, G., Pirali, O., & Cuisset, A. (2015). High-resolution synchrotron far infrared spectroscopy of thionyl chloride: Analysis of the ν3 and ν6 fundamental bands. Spectroscopy with Synchrotron Radiation, 315, 30–36.
Résumé: Thionyl chloride (SOCl2) is a volatile inorganic compounds used extensively in industry. Its monitoring in gas phase is critical both for environmental and defense concerns. Previous high-resolution gas phase spectroscopic studies were focused on the microwave region (below 40GHz) and no rotationally-resolved study of the IR spectrum has been reported to date. We present in this article a rovibrational analysis of the two lowest frequency infrared active bending modes ν3 and ν6 of SOCl2. By means of synchrotron based Fourier-Transform far-infrared spectroscopy on the AILES beamline of the SOLEIL facility, the spectra of the symmetric ν3 (346cm−1) and asymmetric ν6 (283cm−1) fundamental bands have been rotationally resolved and analyzed.
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Martin-Drumel, M. A., Endres, C. P., Zingsheim, O., Salomon, T., van Wijngaarden, J., Pirali, O., Gruet, S., Lewen, F., Schlemmer, S., McCarthy, M. C., & Thorwirth, S. (2015). The SOLEIL view on sulfur rich oxides: The S2O bending mode ν2 at 380cm−1 and its analysis using an Automated Spectral Assignment Procedure (ASAP). Spectroscopy with Synchrotron Radiation, 315, 72–79.
Résumé: The fundamental vibrational bending mode ν2 of disulfur monoxide, S2O, and the associated hot band 2ν2-ν2 have been observed at high spectral resolution for the first time at the SOLEIL synchrotron facility using Fourier-transform far-infrared spectroscopy. This transient species has been produced in a radio-frequency discharge by flowing SO2 over elemental sulfur. The spectroscopic analysis has been performed using the newly developed Automated Spectral Assignment Procedure (ASAP) which has enabled the accurate determination of more than 3500 energy levels of the v2=1and2 vibrational states. The procedure provides a fast and convenient way to analyze large data sets in a straightforward manner, if one of the two vibrational states involved in the transition is accurately known from prior work. In addition to the high-resolution synchrotron study, pure rotational spectra of S2O in the v2=1 and 2 vibrational states were observed in the frequency range 250–500GHz by absorption spectroscopy in a long-path absorption cell. From these combined measurements, extensive molecular parameter sets have been determined, including full sets of sextic and two octic centrifugal distortion terms. Highly accurate band centers (to better than 10-5cm−1) have been derived for both vibrational bands.
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Mengesha, E. T., Zehnacker-Rentien, A., Sepiol, J., Kijak, M., & Waluk, J. (2015). Spectroscopic Study of Jet-Cooled Deuterated Porphycenes: Unusual Isotopic Effects on Proton Tunneling. J. Phys. Chem. B, 119(6), 2193–2203.
Résumé: Porphycene (Pc) is a well-known model for studying double hydrogen transfer, which shows vibrational-mode-specific tunneling splitting when isolated in supersonic jets or helium nanodroplets. The effect of deuteration on tunneling splitting is reported for jet-cooled heterogeneous, deuterated Pc samples (Pc-d(mix)) with the prevailing contribution of Pc-d(12) isotopologue. The sample introduced into the gas phase using laser desorption is studied by means of laser-induced fluorescence (LIF) and single vibronic level fluorescence (SVLF) measurements, in combination with quantum chemical calculations. The influence of molecular symmetry is studied by comparing Pc, Pc-d(12), and Pc-d(11). The spectra of Pc-d(12) show strong similarity to those of the parent undeuterated porphycene (Pc). Comparable tunneling splitting is observed in the two isotopologues, both for the 00 transition and the most efficient promoting 2A(g) mode. In contrast, an unusual isotopic effect is observed for the totally symmetrical 4A(g) mode. While this vibration behaves as a neutral mode in Pc, neither enhancing nor decreasing the tunneling efficiency, it strongly promotes hydrogen transfer in Pc-d(12). This observation is explained in terms of modification of the displacement vectors of the 4A(g) mode upon deuteration. It demonstrates that isotope substitution affects hydrogen transfer even when the weak structural modifications are far from the reaction center, emphasizing the strongly multidimensional nature of the tunneling process.
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Moreira S. V., Keller A., Coudreau T., & Milman P. (2015). Modeling Leggett-Garg inequality violation. Phys. Rev. A, 92, 062132.
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Nie, S. Y., Zhang, X. F., Gref, R., Couvreur, P., Qian, Y., & Zhang, L. J. (2015). Multilamellar Nanoparticles Self-Assembled from Opposite Charged Blends: Insights from Mesoscopic Simulation. Journal Of Physical Chemistry C, 119(35), 20649–20661.
Résumé: Multi lamellar nanoparticles (NPs) are spontaneously formed when mixing two components with opposite charges, meaningful for drug delivery. However, details of NPs association and mechanisms of this process remain largely unknown, due to the limitation of experimental technique. In this work, we use dissipative particle dynamics (DPD) simulation for the first time to determine the structure property relationships of multilamellar NPs formed by charged blends. As a case study, a system with polyanionic fondparinux (Fpx) and cationic derivatives squalenoyl (CSq, including Sql(+) and Sq(++)) in aqueous media is investigated, with a focus on the optimized formation condition and mechanism of regular spherical multilamellar NPs. In particular, we find that highly ordered multilamellar structures tend to form when the nonbonded interaction between Fpx CSq and hydrophobic interaction contributed by CSq are well-balanced. The DPD results strongly agree with corresponding experimental results of this novel nanoparticulate drug carrier. This study could help develop promising multilamellar NPs formed by charged blends through self-assembly for drug delivery.
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Oughaddou, H., Enriquez, H., Tchalala, M.R., Yildirim, H., Mayne, A.J., Bendounan, A., Dujardin, G., Ait Ali, M. & Kara, A. (2015). Silicene: A promising new 2D material. PROGRESS IN SURFACE SCIENCE, 90, 46–83.
Résumé: Silicene is emerging as a two-dimensional material with very attractive electronic properties for a wide range of applications; it is a particularly promising material for nano-electronics in silicon-based technology. Over the last decade, the existence and stability of silicene has been the subject of much debate. Theoretical studies were the first to predict a puckered honeycomb structure
with electronic properties resembling those of graphene. Though these studies were for free-standing silicene, experimental fabrication of silicene has been achieved so far only through epitaxial growth on crystalline surfaces. Indeed, it was only in 2010 that researchers presented the first experimental evidence of the formation
of silicene on Ag(110) and Ag(111), which has launched silicene in a similar way to graphene. This very active field has naturally led to the recent growth of silicene on Ir(111), ZrB2(0001)and Au(110) substrates. However, the electronic properties of epitaxially grown silicene on metal surfaces are influenced by the
strong silicene–metal interactions. This has prompted experimental studies of the growth of multi-layer silicene, though the nature of its ‘‘silicene’’ structure remains questionable. Of course, like graphene, synthesizing free-standing silicene represents the ultimate challenge. A first step towards this has been reported recently through chemical exfoliation from calcium disilicide (CaSi2). In this review, we discuss the experimental and theoretical studies of silicene performed to date. Special attention is given to different experimental studies of the electronic properties of silicene on metal substrates. New avenues for the growth of silicene on other substrates with different chemical characteristics are presented along with foreseeable applications such as nano-devices and novel batteries.
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Palaudoux, J., Sheinerman, S., Soronen, J., Huttula, S. M., Huttula, M., Jankala, K., Andric, L., Ito, K., Lablanquie, P., Penent, F., Bizau, J. M., Guilbaud, S., & Cubaynes, D. (2015). Valence Auger decay following 3s photoionization in potassium. Physical Review A, 92(1), 012510.
Résumé: We have studied photoionization in the inner valence 3s subshell of K and the spectroscopic properties of the two 3s(-1) (S-1) and (S-3) resulting states. Similar to the Rb and Cs cases, the lifetime widths of the (S-1) and (S-3) states are found to be markedly different, due to the electron correlation effects. The main part of the study deals with the subsequent Auger decay of the 3s(-1) states, which have the particularity to involve low energy (similar to 5 eV) Auger electrons. A magnetic bottle spectrometer with a multicoincidence technique has been used to observe and filter the Auger spectra with respect to the K2+ final state. The evolution of these Auger spectra has been investigated near the ionization threshold. They show strong post-collision interaction (PCI) effects, which are well reproduced by semiclassical and eikonal models. They reveal the importance of the photoelectron-Auger-electron interaction associated with these low energy Auger electrons.
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Pirali, O., & Boudon, V. (2015). Synchrotron-based Fourier transform spectra of the ν23 and ν24 IR bands of hexamethylenetetramine C6N4H12. Spectroscopy with Synchrotron Radiation, 315, 37–40.
Résumé: Hexamethylenetetramine (HMT), C6N4H12 is a spherical top with nine IR-active modes. Because of its relevance for astrophysics, we recorded the absorption spectra in the full range of its fundamental bands. In total, we detected eight fundamental bands and recently published the rotational analysis of the four most intense bands (ν19,ν20,ν21,ν22) located in the 1000–1500cm−1 range as a support for astronomical searches (Pirali et al., 2014). While the CH stretch modes are unresolved broad features, in this article we report the analysis of the two remaining fundamental bands exhibiting rotationally resolved structures: ν23–GS and ν24–GS located at about 820cm−1 and 670cm−1, respectively.
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Pirali, O., Kisiel, Z., Goubet, M., Gruet, S., Martin-Drumel, M. A., Cuisset, A., & Hindle, F. and M., G. (2015). Rotation-vibration interactions in the spectra of polycyclic aromatic hydrocarbons: Quinoline as a test-case species. Journal of Chemical Physics, 142(10), 104310.
Résumé: Polycyclic aromatic hydrocarbons (PAHs) are highly relevant for astrophysics as possible, though controversial, carriers of the unidentified infrared emission bands that are observed in a number of different astronomical objects. In support of radio-astronomical observations, high resolution laboratory spectroscopy has already provided the rotational spectra in the vibrational ground state of several molecules of this type, although the rotational study of their dense infrared (IR) bands has only recently become possible using a limited number of experimental set-ups. To date, all of the rotationally resolved data have concerned unperturbed spectra. We presently report the results of a high resolution study of the three lowest vibrational states of quinoline C9H7N, an N-bearing naphthalene derivative. While the pure rotational ground state spectrum of quinoline is unperturbed, severe complications appear in the spectra of the nu(45) and nu(44) vibrational modes (located at about 168 cm(-1) and 178 cm(-1), respectively). In order to study these effects in detail, we employed three different and complementary experimental techniques: Fourier-transform microwave spectroscopy, millimeter-wave spectroscopy, and Fourier-transform far-infrared spectroscopy with a synchrotron radiation source. Due to the high density of states in the IR spectra of molecules as large as PAHs, perturbations in the rotational spectra of excited states should be ubiquitous. Our study identifies for the first time this effect and provides some insights into an appropriate treatment of such perturbations.
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Puthumpally-Joseph, R., Atabek, O., Sukharev, M., & Charron, E. (2015). Theoretical analysis of dipole-induced electromagnetic transparency. PHYSICAL REVIEW A, 91, 043835.
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Ralay-Ranaivo, B., Borgel, D., Couvreur, P., & Gref, R. (2015). Trends in the development of oral anticoagulants. Therapeutic Delivery, 6(6), 685–703.
Résumé: Anticoagulation remains the therapy of choice for the prevention and treatment of venous and arterial thromboembolic disorders which can cause major organ damage or death. Heparins represent the antithrombotic drugs of choice in short and medium-term prophylaxis and therapy of thromboembolic diseases. Fondaparinux, a synthetic and structural analog of the antithrombin-binding pentasaccharide domain of heparin, has selective anti-Xa activity and longer half-life. However, anticoagulants are poorly absorbed by oral route because of their high molecular weight, hydrophilicity and negative charges. Long-term anticoagulation therapy is problematic because of side effects and frequent monitoring. Formulation approaches are particularly promising.
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Rodriguez-Ruiz, V., Maksimenko, A., Anand, R., Monti, S., Agostoni, V., Couvreur, P., Lampropoulou, M., Yannakopoulou, K., & Gref, R. (2015). Efficient “green” encapsulation of a highly hydrophilic anticancer drug in metal-organic framework nanoparticles. Journal Of Drug Targeting, 23(7-8), 759–767.
Résumé: Metal-organic frameworks (MOFs) are coordination polymers of interest for biomedical applications. Of particular importance, nanoparticles made of iron(III) trimesate (MIL-100, MIL standing for Material Institut Lavoisier) (nanoMOFs) can be conveniently synthesised under mild and green conditions. They were shown to be biodegradable, biocompatible and efficient to encapsulate a variety of active molecules. We have addressed here the challenges to encapsulate a highly hydrophilic anticancer prodrug, phosphated gemcitabin (Gem-MP) known for its instability and inability to bypass cell membranes. MIL-100 nanoMOFs acted as efficient “nanosponges”, soaking Gem-MP from its aqueous solution with almost perfect efficiency (>98%). Maximal loadings reached similar to 30 wt% reflecting the strong interaction between the drug and the iron trimesate matrices. Neither degradation nor loss of crystalline structure was observed after the loading process. Storage of the loaded nanoMOFs in water did not result in drug release over three days. However, Gem-MP was released in media containing phosphates, as a consequence to particle degradation. Drug-loaded nanoMOFs were effective against pancreatic PANC-1 cells, in contrast to free drug and empty nanoMOFs. However, an efflux phenomenon could contribute to reduce the efficacy of the nanocarriers. Size optimization and surface modification of the nanoMOFs are expected to further improve these findings.
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Rogez, B., Horeis, R., Le Moal, E., Christoffers, J., Al-Shamery, K., Dujardin, G., & Boer-Duchemin, E. (2015). Optical and electrical excitation of hybrid guided modes in an organic nanofiber-gold film system. J. Phys. Chem. C, 119, 22217.
Résumé: We report on the optical and electrical excitation of the modes of a “hybrid” waveguide consisting of a single organic nano fiber on a thin gold film. In the first set of experiments, light is used to excite the photoluminescence of an organic nano fiber on a thin gold film and the resulting emission is analyzed using Fourier-space leakage radiation microscopy. Two guided modes and the dispersion relations of this hybrid waveguide are thus determined. From numerical calculations, both a fundamental and excited mode of mixed photonic − plasmonic character are identified. In a second experiment, a local electrical nanosource of surface plasmon polaritons (SPPs) is coupled to the hybrid waveguide. The SPP nanosource consists of the inelastic electron tunnel current between the tip of a scanning tunneling microscope (STM) and the gold film. We show that the electrically excited SPPs couple to the fundamental mode and that the coupling efficiency is highest when the SPP nanosource is aligned with the nano fiber axis. Moreover, the electrically excited SPPs strongly scatter into out-of-plane light at the nano fiber end. This light from scattered SPPs measured in the substrate is phase shifted by about π with respect to the direct light emission from beneath the STM tip. These experiments lead to a better understanding of the processes that must be optimized in order to exploit such hybrid waveguide structures.
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Saideh I., Ribeiro A. D., Ferrini G., Coudreau T., Milman P., & Keller A. (2015). General dichotomization procedure to provide qudit entanglement criteria. Phys. Rev. A, 92, 052334.
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Sarsa, A., Alcaraz-Pelegrina, J. M., & Le Sech, C. (2015). Isotopic Effects on Covalent Bond Confined in a Penetrable Sphere. Journal Of Physical Chemistry B, 119(45), 14364–14372.
Résumé: A model of confinement of the covalent bond by a finite potential beyond the Born-Oppenheimer approximation is presented. A two-electron molecule is located at the center of a penetrable spherical cavity. The Schrodinger equation has been solved by using the diffusion Monte Carlo method. Total energies, internuclear distances, and vibrational frequencies of the confined molecular system have been obtained. Even for confining potentials of a few electronvolts, a noticeable increase in the bond energy and the nuclear vibrational frequency is observed, and the internuclear distance is lowered. The gap between the zero point energy of different molecular isotopes increases with confinement. The confinement of the electron pair might play a role in chemical reactivity, providing an alternative explanation for the tunnel effect, when large values of primary kinetic isotopic effect are observed. The Swain-Schaad relation is still verified when confinement changes the zero point energy. A semiquantitative illustration is proposed using the data relative to an hydrogen transfer involving a C-H cleavage catalyzed by the bovine serum amine oxidase. Changes on the confining conditions, corresponding to a confinement/deconfinement process, result in a significant decrease in the activation energy of the chemical transformation. It is proposed that confinement/deconfinement of the electron-pair bonding by external electrostatic forces inside the active pocket of an enzyme could be one of the basic mechanisms of the enzyme catalysis.
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Saunier, J., Herry, J. M., Marliere, C., Renault, M., Bellon-Fontaine, M. N., & Yagoubi, N. (2015). Modification of the bacterial adhesion of Staphylococcus aureus by antioxidant blooming on polyurethane films. Materials Science & Engineering C-Materials For Biological Applications, 56, 522–531.
Résumé: Medical device-related infections are a major problem in hospital. The risk of developing an infection is linked to the bacterial adhesion ability of pathogen strains on the device and their ability to form a biofilm. Here we focused on polymer surfaces exhibiting a blooming of antioxidant (Irganox 3114 (R)) and Irganox 1076 (R)) on their surface. We tried to put into evidence the effect of such a phenomenon on the bacterial adhesion in terms of number of viable cultivable bacteria and bacteria localization on the surface. We showed that the blooming has a tendency to increase the Staphylococcus aureus adhesion phenomenon in part for topographic reasons. (C) 2015 Elsevier B.V. All rights reserved.
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Schubert, A., Falvo, C., & Meier, C. (2015). Vibrational-coherence measurement of nonequilibrium quantum systems by four-wave mixing. Phys. Rev. A, 92, 053402.
Résumé: We show theoretically that a quantum system in a nonequilibrium state interacting with a set of laser pulses in a four-wave-mixing setup leads to signal emission in directions opposite to the ones usually considered. When combined with a pump mechanism which sets a time origin for the nonequilibrium state creation, this particular optical response can be utilized to directly follow decoherence processes in real time. By varying the time delays within the probe sequence, signals in these unconventional directions can also be used to detect two-dimensional spectra determined by the dynamics of up to three-quantum coherences, revealing energetical anharmonicities and environmental influences. As a numerical example, these findings are demonstrated by considering a model of vibrational decoherence of carbon monoxide after photolysis from a hemeprotein.
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Shen, J., Jia, J., Bobrov, K., Guillemot, L., & Esaulov, V. A. (2015). Electron Transfer Processes on Supported Au Nanoclusters and Nanowires and Substrate Effects. J.Phys.Chem.C, 119(27), 15168–15176.
Résumé: The catalytic activity of metal nanoclusters is considered to depend on their size, morphology, and substrate type. Here we address this problem by studying changes in electron transfer processes, that are important in surface chemistry, on the example of the interaction of Li ions with gold nanostructures as a function of their sizes and substrate type. The Au nanoclusters were grown on highly ordered pyrolytic graphite (HOPG) and Al2O3 surfaces. In the case of Al2O3 and sputtered HOPG surface, a wide surface coverage distribution of nanoclusters is formed, whereas on pristine HOPG scanning tunneling microscopy (STM) images show that Au clusters nucleate at step edges and can coalesce into “nanowires”. We found that electron transfer is much more probable on small clusters than on bulk Au surfaces. For distributed clusters, electron transfer is most probable for lateral size is of the order of 2–3 nm and height is in the 1 nm range, that is, of the order of a few atomic layers. Interestingly, larger electron transfer rates were found on cluster chains or nanowires nucleated on HOPG step edges in the case of pristine HOPG than on isolated clusters on HOPG planes. Our results suggest that the main effects that are observed are largely related to cluster size and morphology.
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Soorkia, S., Dehon, C., S, S. K., Perot-Taillandier, M., Lucas, B., Jouvet, C., Barat, M., & Fayeton, J. A. (2015). Ion-Induced Dipole Interactions and Fragmentation Times: Calpha-Cbeta Chromophore Bond Dissociation Channel. J Phys Chem Lett, 6(11), 2070–2074.
Résumé: The fragmentation times corresponding to the loss of the chromophore (Calpha-Cbeta bond dissociation channel) after photoexcitation at 263 nm have been investigated for several small peptides containing tryptophan or tyrosine. For tryptophan-containing peptides, the aromatic chromophore is lost as an ionic fragment (m/z 130), and the fragmentation time increases with the mass of the neutral fragment. In contrast, for tyrosine-containing peptides the aromatic chromophore is always lost as a neutral fragment (mass = 107 amu) and the fragmentation time is found to be fast (<20 ns). These different behaviors are explained by the role of the postfragmentation interaction in the complex formed after the Calpha-Cbeta bond cleavage.
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Spagnoli, S., Morfin, I., Gonzalez, M. A., Carcabal, P., & Plazanet, M. (2015). Solvent Contribution to the Stability of a Physical Gel Characterized by Quasi-Elastic Neutron Scattering. Langmuir, 31(8), 2554–2560.
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Tammaro, S., Pirali, O., Roy, P., Lampin, J. - F., Ducourneau, G., Cuisset, A., Hindle, F., & Mouret, G. (2015). High density THz frequency comb produced by coherent synchrotron radiation. Nat. Commun., 6, 7733.
Résumé: Frequency combs have enabled significant progress in frequency metrology and high-resolution spectroscopy extending the achievable resolution while increasing the signal-to-noise ratio. In its coherent mode, synchrotron radiation is accepted to provide an intense terahertz continuum covering a wide spectral range from about 0.1 to 1 THz. Using a dedicated heterodyne receiver, we reveal the purely discrete nature of this emission. A phase relationship between the light pulses leads to a powerful frequency comb spanning over one decade in frequency. The comb has a mode spacing of 846 kHz, a linewidth of about 200 Hz, a fractional precision of about 2 × 10^{−10} and no frequency offset. The unprecedented potential of the comb for high-resolution spectroscopy is demonstrated by the accurate determination of pure rotation transitions of acetonitrile.
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Tran, H., Vander Auwera, J., Landsheere, X., Ngo, N. H., Pangui, E., Morales, S. B., El Hamzaoui, H., Capoen, B., Bouazaoui, M., Boulet, C., & Hartmann, J. - M. (2015). Infrared light on molecule-molecule and molecule-surface collisions. PRA, 92(1), 012707.
Résumé: By analyzing measured infrared absorption of pure CH4 gas under both “free” (large sample cell) and “confined” (inside the pores of a silica xerogel sample) conditions we give a demonstration that molecule-molecule and molecule-surface collisions lead to very different propensity rules for rotational-state changes. Whereas the efficiency of collisions to change the rotational state (observed through the broadening of the absorption lines) decreases with increasing rotational quantum number J for CH4-CH4 interactions, CH4-surface collisions lead to J-independent linewidths. In the former case, some (weak) collisions are inefficient whereas, in the latter case, a single collision is sufficient to remove the molecule from its initial rotational level. Furthermore, although some gas-phase collisions leave J unchanged and only modify the angular momentum orientation and/or symmetry of the level (as observed through the spectral effects of line mixing), this is not the case for the molecule-surface collisions since they always change J (in the studied J=0–14 range).
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Turowski, M., Crepin, C., Douin, S., & Kolos, R. (2015). Formation and Spectroscopy of Dicyanotriacetylene (NC8N) in Solid Kr. Journal Of Physical Chemistry A, 119(11), 2701–2708.
Résumé: Thermally induced creation of dicyanotriacetylene (NC8N) was observed in solid krypton. Samples were obtained by cryogenic trapping of gaseous cyanoacetylene/Kr mixtures subjected to electric discharges. Strong a (3)Sigma(+)(u) -> X (1)Sigma(+)(g) phosphorescence of NC8N is reported here for the first time; its vibronic structure permitted the measurement of several ground-state vibrational frequencies. Other chemical species, mostly smaller than the precursor molecule, have also been formed, among them the dicarbon molecule (C-2), and these may serve as indispensable building blocks in the NC8N synthesis. Processes leading to the elongation of cyanoacetylenic chains are of potential importance for the chemistry of icy grains present in the interstellar gas clouds.
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Urbain, X., Bech, D., Van Roy, J. P., Geleoc, M., Weber, S. J., Huetz, A., & Picard, Y. J. (2015). A zero dead-time multi-particle time and position sensitive detector based on correlation between brightness and amplitude. Review Of Scientific Instruments, 86(2), 023305.
Résumé: A new multi-particle time and position sensitive detector using only a set of microchannel plates, a waveform digitizer, a phosphor screen, and a CMOS camera is described. The assignment of the timing information, as taken from the microchannel plates by fast digitizing, to the positions, as recorded by the camera, is based on the COrrelation between the BRightness of the phosphor screen spots, defined as their integrated intensity and the Amplitude of the electrical signals (COBRA). Tests performed by observing the dissociation of HeH, the fragmentation of H-3 into two or three fragments, and the photo-double-ionization of Xenon atoms are presented, which illustrate the performances of the COBRA detection scheme. (C) 2015 AIP Publishing LLC.
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Wakelam, V., Loison, J. C., Herbst, E., Pavone, B., Bergeat, A., Béroff, K., Chabot, M., Faure, A., Galli, D., Geppert, W. D., Gerlich, D., Gratier, P., Harada, N., Hickson, K. M., Honvault, P., Klippenstein, S. J., Le Picard, S. D., Nyman, G., Ruaud, M., Schlemmer, S., Sims, I. R., Talbi, D., Tennyson, J., & and Wester, R. (2015). The 2014 KIDA Network for Interstellar Chemistry. The Astrophysical Journal Supplement Series, 217(2), 20.
Résumé: Chemical models used to study the chemical composition of the gas and the ices in the interstellar medium are based on a network of chemical reactions and associated rate coefficients. These reactions and rate coefficients are partially compiled from data in the literature, when available. We present in this paper kida.uva.2014, a new updated version of the kida.uva public gas-phase network first released in 2012. In addition to a description of the many specific updates, we illustrate changes in the predicted abundances of molecules for cold dense cloud conditions as compared with the results of the previous version of our network, kida.uva.2011.
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Wang, T., Rogez, B., Comtet, G., Le Moal, E., Abidi, W., Remita, H., Dujardin, G., & Boer-Duchemin, E. (2015). Scattering of electrically excited surface plasmon polaritons by gold nanoparticles studied by optical interferometry with a scanning tunneling microscope. Phys. Rev. B, 92(4), 045438.
Résumé: We study the scattering of electrically excited surface plasmon polaritons (SPP) from individual nanostructures. The tunneling electrons from a scanning tunneling microscope (STM) are used to excite an out-going, circular SPP wave on a thin (50-nm) gold film on which isolated gold nanoparticles (NPs) have been deposited. Interaction of the excited SPPs with theNPs leads to both in-plane (SPP-to-SPP) and out-of-plane (SPP-to-photon) scattering. We use SPP leakage radiation microscopy to monitor the interference between the incident and in-plane scattered SPP waves in the image plane. By changing the location of the STM tip, the distance of the pointlike SPP source to the scatterers can be varied at will, which constitutes a key advantage over other existing techniques. As well, the out-of-plane scattered radiation interferes with the direct light emission from the STM tip in the back focal plane (Fourier plane). This confirms the mutual coherence of the light and SPP emission resulting from the inelastic tunneling of an electron in the STM junction. We use this effect to demonstrate that SPP-to-photon scattering at NPs is highly directional.
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Wardé, M., Herinx, M., Ledieu, J., Serkovic Loli, L. N., Fournée, V., Gille, P., Le Moal, S., & Barthés-Labrousse, M. - G. (2015). Adsorption of O2 and C2Hn (n=2, 4, 6) on the Al9Co2(001) and o-Al13Co4(100) complex metallic alloy surfaces. Appl. Surf. Sci., 357, 1666–1676.
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Weber, S. J., Manschwetus, B., Billon, M., Bottcher, M., Bougeard, M., Breger, P., Geleoc, M., Gruson, V., Huetz, A., Lin, N., Picard, Y. J., Ruchon, T., Salieres, P., & Carre, B. (2015). Flexible attosecond beamline for high harmonic spectroscopy and XUV/near-IR pump probe experiments requiring long acquisition times. Review Of Scientific Instruments, 86(3), 033108.
Résumé: We describe the versatile features of the attosecond beamline recently installed at CEA-Saclay on the PLFA kHz laser. It combines a fine and very complete set of diagnostics enabling high harmonic spectroscopy (HHS) through the advanced characterization of the amplitude, phase, and polarization of the harmonic emission. It also allows a variety of photo-ionization experiments using magnetic bottle and COLTRIMS (COLd Target Recoil Ion Momentum Microscopy) electron spectrometers that may be used simultaneously, thanks to a two-foci configuration. Using both passive and active stabilization, special care was paid to the long term stability of the system to allow, using both experimental approaches, time resolved studies with attosecond precision, typically over several hours of acquisition times. As an illustration, applications to multi-orbital HHS and electron-ion coincidence time resolved spectroscopy are presented.(C) 2015 AIP Publishing LLC.
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Wei, F., Tian, K., & Zheng, W. (2015). Interfacial Structure and Transformation of Guanine-Rich Oligonucleotides on Solid Supported Lipid Bilayer Investigated by Sum Frequency Generation Vibrational Spectroscopy. J. Phys. Chem. C, 119(48), 27038–27044.
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Wei, F., Xiong, W., Li, W., Lu, W., Allen, H. C., & Zheng, W. (2015). Assembly and relaxation behaviours of phosphatidylethanolamine monolayers investigated by polarization and frequency resolved SFG-VS. PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 17(38), 25114–22.
Résumé: The assembly conformation and kinetics of phosphatidylethanolamine (PE) lipids are the key to their membrane curvatures and activities, such as exocytosis, endocytosis and Golgi membrane fusion. In the current study, a polarization and frequency resolved (bandwidth 1 cm(-1)) picosecond sum frequency generation (SFG) system was developed to characterize phosphatidylethanolamine monolayers. In addition to obtaining pi-A isotherms and Brewster angle microscopy (BAM) images, the conformational changes and assembly behaviors of phosphatidylethanolamine molecules are investigated by analyzing the SFG spectra collected at various surface pressures (SPs). The compression kinetics and relaxation kinetics of phosphatidylethanolamine monolayers are also reported. The conformational changes of PE molecules during the monolayer compression are separated into several stages: reorientation of the head group PO2(-) in the beginning of the liquid-expanded (LE) phase, conformational changes of head group alkyl chains in the LE phase, and conformational changes of tail group alkyl chains in the LE-liquid condensed (LE-LC) phase. Such an understanding may help researchers to effectively control the lipid molecular conformation and membrane curvatures during the exocytosis/endocytosis processes.
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Yengui, M., & Riedel, D. (2015). Evidence of Low Schottky Barrier Effects and the Role of Gap State in the Electronic Transport Through Individual CoSi2 Silicide Nano-Islands at Low Temperature (9K). JOURNAL OF PHYSICAL CHEMISTRY C, 119, 22700.
Résumé: In this paper, we study the electronic properties of CoSi2 metallic islands grown on a Si(100) surface with a low-temperature (9 K) scanning tunneling microscope (STM). The atomic scale structures of the flat and ridge silicide islands surfaces are described with an ultimate resolution, thanks to the stability of low-temperature STM. A statistical study of the I−V and dI/dV signals acquired along the islands shows their metallic-like properties and a very small residual conduction band gap of ∼30 mV. This reveals that the electronic transport through the individual metallic islands at the silicide−silicon interface is mainly ruled by electronic tunnel processes for positive sample biases and driven by the presence of gap states for negative sample voltage. The role of the gap states is demonstrated by performing conductance measurements along the dimer vacancy lines in which interstitial Co atoms are accessible at the silicon surface. Hence, the electronic transport that occurs from the silicide−silicon interface toward the macroscopic contact of the sample can be explained.
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Yengui, M., Pinto, H., Leszczynski, J. & Riedel, D. (2015). Atomic scale study of corrugating and anticorrugating states on the bare Si(1 0 0) surface. JOURNAL OF PHYSICS-CONDENSED MATTER, 27(4), 045001.
Résumé: In this article, we study the origin of the corrugating and anticorrugating states through the electronic properties of the Si(1 0 0) surface via a low-temperature (9 K) scanning tunneling microscope (STM). Our study is based on the analysis of the STM topographies corrugation variations when related to the shift of the local density of states (LDOS) maximum in the [1-10] direction. Our experimental results are correlated with numerical simulations using the density-functional theory with hybrid Heyd–Scuseria–Ernzerhof (HSE06) functional to simulate the STM topographies, the projected density of states variations at different depths in the silicon surface as well as the three dimensional partial charge density distributions in real-space. This work reveals that the Si(1 0 0) surface exhibits two anticorrugating states at +0.8 and +2.8V that are associated with a phase shift of the LDOS maximum in the unoccupied states STM topographies. By comparing the calculated data with our experimental results, we have been able to identify the link between the variations of the STM topographies corrugation and the shift of the LDOS maximum observed experimentally. Each surface voltage at which the STM topographies corrugation drops is defined as anticorrugating states. In addition, we have evidenced a sharp jump in the tunnel current when the second LDOS maximum shift is probed, whose origin is discussed and associated with the presence of Van Hove singularities.
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Zapata, M., Camacho Beltran, A. S., Borisov, A. G., & Aizpurua, J. (2015). Quantum effects in the optical response of extended plasmonic gaps: validation of the quantum corrected model in core-shell nanomatryushkas. Opt. Express, 23(6), 8134–8149.
Résumé: Electron tunneling through narrow gaps between metal nanoparticles can strongly affect the plasmonic response of the hybrid nanostructure. Although quantum mechanical in nature, this effect can be properly taken into account within a classical framework of Maxwell equations using the so-called Quantum Corrected Model (QCM). We extend previous studies on spherical cluster and cylindrical nanowire dimers where the tunneling current occurs in the extremely localized gap regions, and perform quantum mechanical time dependent density functional theory (TDDFT) calculations of the plasmonic response of cylindrical core-shell nanoparticles (nanomatryushkas). In this axially symmetric situation, the tunneling region extends over the entire gap between the metal core and the metallic shell. For core-shell separations below 0.5 nm, the standard classical calculations fail to describe the plasmonic response of the cylindrical nanomatryushka, while the QCM can reproduce the quantum results. Using the QCM we also retrieve the quantum results for the absorption cross section of the spherical nanomatryushka calculated by V. Kulkarni et al. [Nano Lett. 13, 5873 (2013)]. The comparison between the model and the full quantum calculations establishes the applicability of the QCM for a wider range of geometries that hold tunneling gaps.
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Zehnacker, A. (2015). Optical spectroscopy coupled with mass spectrometry methods. Physical Chemistry Chemical Physics, 17(39), 25672–25675.
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Zugarramurdi, A., Momeni, A., Debiossac, M., Lunca-Popa, P., Mayne, A.J., Borisov, A.G., Mu, Z., Roncin, P. & Khemliche, H. (2015). Determination of the geometric corrugation of graphene on SiC(0001) by grazing incidence fast atom diffraction. Appl. Phys. Lett., 106(10), 101902.
Résumé: We present a grazing incidence fast atom diffraction (GIFAD) study of monolayer graphene on 6H-SiC(0001). This system shows a Moiré-like 13x13 superlattice above the reconstructed carbon buffer layer. The averaging property of GIFAD results in electronic and geometric corrugations that are well decoupled; the graphene honeycomb corrugation is only observed with the incident beam parallel to the zigzag direction while the geometric corrugation arising from the superlattice is revealed along the armchair direction. Full-quantum calculations of the diffraction patterns show the very high GIFAD sensitivity to the amplitude of the surface corrugation. The best agreement between the calculated and measured diffraction intensities yields a corrugation height of 0.27 +- 0.3A° .
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Procédures de Conférences |
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Briant, M., Poisson, L., Shafizadeh, N., & Soep, B. (2015). Tribute to Jean-Michel Mestdagh (Vol. 119). American Chemical Society.
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Klisnick, A., & Menoni, C. S. (2015). X-Ray Lasers and Coherent X-Ray Sources: Development and Applications XI Introduction (Vol. 9589).
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Actes de Conférences |
Bizau, J. M., Cubaynes, D., Guilbaud, S., Al Shorman, M. M., Penent, F., Lablanquie, P., Andric, L., Palaudoux, J., & Blancard, C. (2015). Auger decay of the 4d(9)5s(2)5pnf excited states of Xe5+ ion. In Xxix International Conference On Photonic (Vol. 635).
Résumé: The Auger decay of the 4d --> nf (n = 4 to 6) photoexcitations in Xe5+ ion has been measured using electron spectrometry. MCDF calculations allow to interpret the recorded electron spectra.
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Boer-Duchemin, E., Wang, T., Le Moal, E., Dujardin, G. (2015). Electrically-driven surface plasmon nanosources. In PROCEEDINGS OF SPIE (Vol. 9361, 93610R).
Résumé: Electrical nanosources of surface plasmons will be an integral part of any future plasmonic circuits. Three different types of such nanosources (based on inelastic electron tunneling, high energy electron bombardment, and the electrical injection of a semiconductor device) are briefly described here. An example of a fundamental experiment using an electrical nanosource consisting of the tunnel junction formed between a scanning tunneling microscope (STM) and a metallic sample is given. In this experiment, the temporal coherence of the broadband STM-plasmon source is probed using a variant of Young's double slit experiment, and the coherence time of the broadband source is estimated to be about 5-10 fs.
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Gharaibeh, M. F., Bizau, J. M., Cubaynes, D., Guilbaud, S., Al Shorman, M. M., Ababneh, I. Q., Sakho, I., Blancard, C., & McLaughlin, B. M. (2015). K-Shell Photoionization of the Oxygen Isonuclear Sequence. In Xxix International Conference On Photonic (Vol. 635).
Résumé: K-shell photoionization cross-section measurements for the oxygen isonuclear sequence from N-like to Li-like made at the SOLEIL Light Source are compared with SUNC, MCDF and R-matrix calculations.
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Lefebvre R. (2015). Intense-field molecular photodissociation : the adiabatic views. In Frontiers in Quantum Methods and Applications in Chemistry and Physics, XIX (pp. 135–145).
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Sheinerman, S., Lablanquie, P., Andric, L., Ito, K., Palaudoux, J., Huttula, S. M., Huttula, M., Jankala, K., Soronen, J., Bizau, J., Guilbaud, S., Cubaynes, D., & Penent, F. (2015). Post-collision interaction in Potassium 3s photoionization. In Xxix International Conference On Photonic (Vol. 635).
Résumé: The post-collision interaction (PCI) distortion of the Auger electron line shapes after K 3s photoionization is revealed in coincidence measurements and confirmed by calculations.
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Urbain, X., Bech, D., Van Roy, J. P., Geleoc, M., Weber, S. J., Huetz, A., & Picard, Y. (2015). COBRA: a zero-deadtime camera based multiparticle detector. In Xxix International Conference On Photonic (Vol. 635).
Résumé: A new time and position sensitive detector is described, which combines an MCP stack with phosphor screen, a CMOS camera and a waveform digitizer. Particle identification relies on the correlation between brightness of phosplior screen spots and amplitude of electrical signals (COBRA).
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Veyrinas, K., Gruson, V., Weber, S. J., Barreau, L., Ruchon, T., Houver, J. C., Carre, B., Lucchese, R. R., Salieres, P., & Dowek, D. (2015). Molecular frame photoemission: a sensitive probe of the complete polarization state of high harmonic generation. In J. Phys.: Conf. Ser. (Vol. 635, 112140).
Résumé: Molecular polarimetry, based on the determination of molecular frame photoemission in dissociative photoionization (DPI) studied by electron-ion coincident momentum spectroscopy, allows us to measure the complete state of elliptically polarized light. Here, we demonstrate the first complete characterization of high-order harmonic polarization state for three benchmark generation processes with inherent symmetry breaking based on the polarization of the generating beam (elliptical or counter-rotating fields) or on anisotropic targets e.g. aligned molecules. The ability to disentangle circular and unpolarized components of the XUV pulses is of particular interest to qualify the HHG sources.
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Chapitres de Livres |
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Cocinero, E. J., & Carcabal, P. (2015). Carbohydrates. In Gas-Phase Ir Spectroscopy And Structure Of Biological Molecules (Vol. 364, pp. 299–333).
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Giesen, T. R., G.A., Maier, J. P., Carpentier, Y., Rouillé, G., Steglich, M., Jäger, C., Henning, T., Huisken, F., Oomens, J., Pirali, O., Tielens, A. G. G. M. and Müller, H. S. P. (2015). In Wiley-VCH (Ed.), Molecular Spectroscopy In Laboratory Astrochemistry. From Molecules through Nanoparticles to Grains (pp. 13–108).
Résumé: pp. 13–108 Wiley-VCH, 2015 – ISBN: 9783527408894 (Print) – ISBN: 9783527653133 (Online)
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