Peer-reviewed Publications |
Perez-Lloret M, Fraix A, Petralia S, Conoci, S., Tafani V, Cutrone, G., Vargas-Berenguel, A., Gref R, & Sortino S. (2019). One-Step Photochemical Green Synthesis of Water-Dispersible Ag, Au, and Au@Ag Core-Shell Nanoparticles. Chemistry, 25(64), 14638.
Résumé: A simple and green synthetic protocol for the rapid and effective preparation of Ag, Au and Au@Ag core-shell nanoparticles (NPs) is reported based on the light irradiation of a biocompatible, water-soluble dextran functionalized with benzophenone (BP) in the presence of AgNO3 , HAuCl4 , or both. Photoactivation of the BP moiety produces the highly reducing ketyl radicals through fast (<50 ns) intramolecular H-abstraction from the dextran scaffold, which, in turn, ensures excellent dispersibility of the obtained metal NPs in water. The antibacterial activity of the AgNPs and the photothermal action of the Au@Ag core-shell are also shown.
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Aguilar-Galindo, F., Diaz-Tendero, S., & Borisov, A. G. (2019). Electronic Structure Effects in the Coupling of a Single Molecule with a Plasmonic Antenna. J. Phys. Chem. C, 123(7), 4446–4456.
Résumé: Miniaturization of plasmonic devices and the possibility to address single-molecule quantum emitters (QEs) in plasmonic cavities allow one to approach a regime where the characteristic sizes of the system are on the scale of molecular dimensions. In such a situation, the actual spatial profile of the transition electron density associated with a molecular exciton affects the coupling between molecular excitons and metal (nano)objects. Using a quantum approach, we address the energies and lifetimes of the excited states of the zinc phthalocyanine dye molecule placed in the nanometer vicinity of a plasmonic antenna. We demonstrate that the interaction between the molecular excitons and a metal nanoparticle reflects the gross features of the atomic structure in the molecule. The possibility to “look” inside the molecule does not require the presence of atomic scale probes on the surfaces of plasmonic nanoparticles, which would lead to the corresponding localization of the optical field. We show that the QE itself simultaneously generates highly localized fields and probes them via self-interaction.
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Aguirregabiria, G., Marinica, D. C., Ludwig, M., Brida, D., Leitenstorfer, A., Aizpurua, J., & Borisov, A. G. (2019). Dynamics of electron-emission currents in plasmonic gaps induced by strong fields. Faraday Discus., 214, 147–157.
Résumé: The dynamics of ultrafast electron currents triggered by femtosecond laser pulse irradiation of narrow gaps in a plasmonic dimer is studied using quantum mechanical Time-Dependent Density Functional Theory (TDDFT). The electrons are injected into the gap due to the optical field emission from the surfaces of the metal nanoparticles across the junction. Further evolution of the electron currents in the gap is governed by the locally enhanced electric fields. The combination of TDDFT and classical modelling of the electron trajectories allows us to study the quiver motion of the electrons in the gap region as a function of the Carrier Envelope Phase (CEP) of the incident pulse. In particular, we demonstrate the role of the quiver motion in establishing the CEP-sensitive net electric transport between nanoparticles.
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Alyabyeva, N., Ouvrard, A., Lazzari, R., & Bourguignon B. (2019). Ordered Hybrid Assembly of Palladium Nanoparticles and Perylene Molecules on an Alumina Template. J. Phys. Chem. C, 123(31), 19175–19182.
Résumé: Combining in a synergic way inorganic and organic matter at a nanometer level has become a key research pathway for nanoelectronics, light harvesting, energy storage, or sensing. Herein, we demonstrate the nanoscale ordering at room temperature of a two-dimensional hybrid assembly combining a long-range ordered array of Pd nanoparticles (NPs) with perylene molecules. The ordering, driven by the periodic superstructure of the Al2O3 ultrathin layer support, has been achieved for 0.9 nm diameter NPs and flat-lying molecules with a 2:1 perylene/NP relative ratio. At a larger NP size and perylene coverage, molecules tilt up on alumina and adsorb on NPs. Combined near-field microscopy and optical spectroscopies provide a detailed understanding of the structural properties as a function of NP size and molecular coverage. This hybrid assembly opens the way to study at the molecular level the optical and electronic properties resulting from the coupling of organic molecules and nanoparticles using multiscale surface sensitive techniques.
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Alyabyeva, N., Ouvrard, A., Zakaria, A. M., & Bourguignon, B. (2019). Probing nanoparticle geometry down to subnanometer size: The benefits of vibrational spectroscopy. J. Phys. Chem. Lett., 10(3), 624–629.
Résumé: Understanding the role of nanoparticle size and shape in the binding of molecules is very relevant for heterogeneous catalysis and molecular electronics. The geometry of Pd nanoparticles (NPs) has been studied from very small clusters containing 4 atoms up to large (>500 atoms), well-faceted NPs. Their geometry was retrieved by combining scanning tunneling microscopy and vibrational sum frequency generation (SFG) spectroscopy of adsorbed CO. SFG has been revealed to be highly sensitive to the geometry of NPs smaller than 100 atoms by identifying the nature of CO adsorption sites. NP growth could be followed layer by layer in the critical size range corresponding to the transition from a nonmetallic to a metallic state and to oscillations of CO adsorption energy. NP height remained at two Pd planes up to 30 atoms, and adsorption energy minima correspond to the completion of successive layers.
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Amri S., Corgier R., Sugny D., Rasel E. M., Gaaloul N., & Charron E. (2019). Optimal control of the transport of Bose-Einstein condensates with atom chips. Sci. Rep., 9, 5346.
Résumé: Using Optimal Control Theory (OCT), we design fast ramps for the controlled transport of Bose-Einstein condensates with atom chips’ magnetic traps. These ramps are engineered in the context of precision atom interferometry experiments and support transport over large distances, typically of the order of 1 mm, i.e. about 1,000 times the size of the atomic clouds, yet with durations not exceeding 200 ms. We show that with such transport durations of the order of the trap period, one can recover the ground state of the final trap at the end of the transport. The performance of the OCT procedure is compared to that of a Shortcut-To-Adiabaticity (STA) protocol and the respective advantages/disadvantages of the OCT treatment over the STA one are discussed.
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Asselin, P., Bruckhuisen, J., Roucou, A., Goubet, M., Martin-Drumel, M. - A., Jabri, A., Belkhodja, Y., Soulard, P., Georges, R., & Cuisset, A. (2019). Jet-cooled rovibrational spectroscopy of methoxyphenols using two complementary FTIR and QCL based spectrometers. The Journal of Chemical Physics, 151(19), 194302.
Résumé: Methoxyphenols (MPs) are a significant component of biomass burning emissions which mainly exists in our atmosphere in the gas phase where they contribute to the formation of secondary organic aerosols (SOAs). Rovibrational spectroscopy is a promising tool to monitor atmospheric MPs and infer their role in SOA formation. In this study, we bring a new perspective on the rovibrational analysis of MP isomers by taking advantage of two complementary devices combining jet-cooled environments and absorption spectroscopy: the Jet-AILES and the SPIRALES setups. Based on Q-branch frequency positions measured in the Jet-AILES Fourier-transform infrared (FTIR) spectra and guided by quantum chemistry calculations, we propose an extended vibrational and conformational analysis of the different MP isomers in their fingerprint region. Some modes such as far-IR out-of-plane –OH bending or mid-IR in-plane –CH bending allow us to assign individually all the stable conformers. Finally, using the SPIRALES setup with three different external cavity quantum cascade laser sources centered on the 930–990 cm−1 and the 1580–1690 cm−1 ranges, it was possible to proceed to the rovibrational analysis of the ν18 ring in-plane bending mode of the MP meta isomer providing a set of reliable excited state parameters, which confirms the correct assignment of two conformers. Interestingly, the observation of broad Q-branches without visible P- and R-branches in the region of the C–C ring stretching bands was interpreted as being probably due to a vibrational perturbation. These results highlight the complementarity of broadband FTIR and narrowband laser spectroscopic techniques to reveal the vibrational conformational signatures of atmospheric compounds over a large infrared spectral range.
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Atabek, O., & Lefebvre, R. (2019). Zero-width resonances in the context of Fano's configuration interaction formalism. Molecular Physics, 117(15-16), 2010–2013.
Résumé: We examine how to link two approaches for resonance width calculations, in a situation of crossing of two diatomic molecular potentials. One is the semiclassical formalism of Child. The other is Fano's configuration interaction approach leading to the Fermi golden rule. We build a case where the vanishing of the width in the two formalisms can be reduced to the same conditions.
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Augé, B., Dartois, E., Duprat, J., Engrand, C., Slodzian, G., Wu, T. D., Guerquin-Kern, J. L., Vermesse, H., Agnihotri, A. N., Boduch, P., & Rothard, H. (2019). Hydrogen isotopic anomalies in extraterrestrial organic matter: role of cosmic ray irradiation and implications for UCAMMs. A&A, 627.
Résumé: Context. Micrometeorites represent, at timescales shorter than a few million years, the dominant source of extraterrestrial matter at the surface of the Earth. Analyses of ultracarbonaceous micrometeorites recovered from Antarctica, known as UCAMMs reveal an exceptionally N-rich organic matter associated with spatially extended high D enrichments. Experiments show that this specific organic matter might have been formed in the outer solar system by energetic irradiation of N-rich icy surfaces.
Aims. We experimentally investigate the hydrogen isotopic fractionation resulting from irradiation of normal and D-rich N2-CH4 ices by high energy ions, simulating the exposition to Galactic cosmic rays of icy bodies surfaces orbiting at large heliocentric distances.
Methods. Films of N2-CH4 ices and a N2-CH4/CD4/N2-CH4 “sandwich” ice were exposed to 129Xe13+ ion beams at 92 and 88 MeV. The chemical evolution of the samples was monitored using in situ Fourier transform infrared spectroscopy. After irradiation, targets were annealed to room temperature. The solid residues of the whole process left after ice sublimation were characterized in situ by infrared spectroscopy, and the hydrogen isotopic composition measured ex situ by imaging secondary ion mass spectrometry at the sub-micron scale (NanoSIMS).
Results. Irradiation leads to the formation of new molecules and radicals. After annealing, the resulting poly-HCN-like macro-molecular residue exhibits an infrared spectrum close to that of UCAMMs. The residue resulting from irradiation of N2-CH4 ices does not exhibit a significant deuterium enrichment comparable to that found in extraterrestrial organic matter. The residue formed by irradiation of D-rich ices shows the formation of isotopic heterogeneities with localised hotspots and an extended contribution likely due to the diffusion of the radiolytic products from the D-rich layer.
Conclusions. These results show that high-energy cosmic ray irradiation does not induce the large hydrogen isotopic fractionation observed at small spatial scale in interplanetary organics. By contrast, large D/H ratio heterogeneities at the sub-micron spatial scale in extraterrestrial organic matter can result from isotopically heterogeneous ices mixtures (i.e. condensed with different D/H ratios), which were transformed into refractory organic matter upon irradiation.
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Ben Nasr, F., Alata, I., Scuderi, D., Lepere, V., Brenner, V., Jaidane, N. E., & Zehnacker, A. (2019). Effects of complexation with sulfuric acid on the photodissociation of protonated Cinchona alkaloids in the gas phase. Physical Chemistry Chemical Physics, 21(28), 15439–15451.
Résumé: The effect of complexation with sulfuric acid on the photo-dissociation of protonated Cinchona alkaloids, namely cinchonidine (Cd), quinine (Qn) and quinidine (Qd), is studied by combining laser spectroscopy with quantum chemical calculations. The protonated complexes are structurally characterized in a room-temperature ion trap by means of infra-red multiple photon dissociation (IRMPD) spectroscopy in the fingerprint and the nu(XH) (X = C, N, O) stretch regions. Comparison with density functional theory calculations including dispersion (DFT-D) unambiguously shows that the complex consists of a doubly protonated Cinchona alkaloid strongly bound to a bisulfate HSO4- anion, which bridges the two protonated sites of the Cinchona alkaloid. UV excitation of the complex does not induce loss of specific photo fragments, in contrast to the protonated monomer or dimer, for which photo-specific fragments were observed. Indeed the UV-induced fragmentation pattern is identical to that observed in collision-induced dissociation experiments. Analysis of the nature of the first electronic transitions at the second order approximate coupled-cluster level (CC2) explains the difference in the behavior of the complex relative to the monomer or dimer towards UV excitation.
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Boutéraon, T., Habart, E., Ysard, N., Jones, A. P., Dartois, E., & Pino, T. (2019). Carbonaceous nano-dust emission in proto-planetary discs: the aliphatic-aromatic components★. A&A, 623.
Résumé: Context. In the interstellar medium, carbon (nano-)grains are a major component of interstellar dust. This solid phase is more vulnerable to processing and destruction than its silicate counterpart. It exhibits a complex, size-dependent evolution that is due to interactions within different radiative and dynamical environments. Infrared signatures of these carbon nano-grains are seen in a large number of discs around Herbig HAeBe stars.
Aims. We probe the composition and evolution of carbon nano-grains at the surface of (pre-)transitional proto-planetary discs around Herbig stars.
Methods. We present spatially resolved infrared emission spectra obtained with the Nasmyth Adaptive Optics System (NAOS) Near-Infrared Imager and Spectrograph (CONICA) at the Very Large Telescope (VLT) in the 3–4 μm range with a spatial resolution of 0.1′′, which allowed us to trace aromatic, olefinic, and aliphatic bands that are attributed to sub-nanometer hydrocarbon grains. We applied a Gaussian fitting to analyse the observed spectral signatures. Finally, we propose an interpretation in the framework of the The Heterogeneous dust Evolution Model of Interstellar Solids (THEMIS).
Results. We show the presence of several spatially extended spectral features that are related to aromatic and aliphatic hydrocarbon material in discs around Herbig stars, from ~10 to 50–100 au, and even in inner gaps that are devoid of large grains. The correlation and constant intensity ratios between aliphatic and aromatic CH stretching bands suggests a common nature of the carriers. Given their expected high destruction rates through UV photons, our observations suggest that they are continuously replenished at the disc surfaces.
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Brand, C., Debiossac, M., Susi, T., Aguillon, F., Kotakoski, J., Roncin P., & Arndt, M. (2019). Coherent diffraction of hydrogen through the 246 pm lattice of graphene. New J. Phys., 21, 033004.
Résumé: We study the diffraction of neutral hydrogen atoms through suspended single-layer graphene using molecular dynamics simulations based on density functional theory. Although the atoms have to overcome a transmission barrier, we find that the de Broglie wave function for H at 80 eV has a high probability to be coherently transmitted through about 18% of the graphene area, contrary to the case of He. We propose an experiment to realize the diffraction of atoms at the natural hexagon lattice period of 246 pm, leading to a more than 400-fold increase in beam separation of the coherently split atomic wave function compared to diffraction experiments at state-of-the art nano-machined masks. We expect this unusual wide coherent beam splitting to give rise to novel applications in atom interferometry.
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Brand, C., Debiossac, M., Susi, T., Aguillon, F., Kotakoski, J., Roncin, P., & Arndt, M. (2019). Coherent diffraction of hydrogen through the 246 pm lattice of graphene. NEW JOURNAL OF PHYSICS, 21(3), 033004.
Résumé: We study the diffraction of neutral hydrogen atoms through suspended single-layer graphene using molecular dynamics simulations based on density functional theory. Although the atoms have to overcome a transmission barrier, we find that the de Broglie wave function for H at 80 eV has a high probability to be coherently transmitted through about 18% of the graphene area, contrary to the case of He. We propose an experiment to realize the diffraction of atoms at the natural hexagon lattice period of 246 pm, leading to a more than 400-fold increase in beam separation of the coherently split atomic wave function compared to diffraction experiments at state-of-the art nano-machined masks. We expect this unusual wide coherent beam splitting to give rise to novel applications in atom interferometry.
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Cabriel C,., Bourg N, Jouchet, P., Dupuis, G., Leterrier, C., Baron A, Badet-Denisot, M. - A., Vauzeilles,, Fort, E.,, & Leveque-Fort S. (2019). Combining 3D single molecule localization strategies for reproducible bioimaging. Nat Commun, 10, 1980.
Résumé: Here, we present a 3D localization-based super-resolution technique providing a slowly varying localization precision over a 1 mum range with precisions down to 15 nm. The axial localization is performed through a combination of point spread function (PSF) shaping and supercritical angle fluorescence (SAF), which yields absolute axial information. Using a dual-view scheme, the axial detection is decoupled from the lateral detection and optimized independently to provide a weakly anisotropic 3D resolution over the imaging range. This method can be readily implemented on most homemade PSF shaping setups and provides drift-free, tilt-insensitive and achromatic results. Its insensitivity to these unavoidable experimental biases is especially adapted for multicolor 3D super-resolution microscopy, as we demonstrate by imaging cell cytoskeleton, living bacteria membranes and axon periodic submembrane scaffolds. We further illustrate the interest of the technique for biological multicolor imaging over a several-mum range by direct merging of multiple acquisitions at different depths.
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Cao, S., Achlan, M., Bryche, J. - F., Gogol, P., Dujardin, G., Raşeev, G., Le Moal, E., & Boer-Duchemin, E. (2019). An electrically induced probe of the modes of a plasmonic multilayer stack. Opt. Express, 27(23), 33011.
Résumé: A new single-image acquisition technique for the determination of the dispersion relation of the propagating modes of a plasmonic multilayer stack is introduced. This technique is based on an electrically-driven, spectrally broad excitation source which is nanoscale in size: the inelastic electron tunnel current between the tip of a scanning tunneling microscope (STM) and the sample. The resulting light from the excited modes of the system is collected in transmission using a microscope objective. The energy-momentum dispersion relation of the excited optical modes is then determined from the angle-resolved optical spectrum of the collected light. Experimental and theoretical results are obtained for metal-insulator-metal (MIM) stacks consisting of a silicon oxide layer (70, 190 or 310 nm thick) between two gold films (each with a thickness of 30 nm). The broadband characterization of hybrid plasmonic-photonic transverse magnetic (TM) modes involved in an avoided crossing is demonstrated and the advantages of this new technique over optical reflectivity measurements are evaluated
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Chamakhi R., Telmini M., Atabek O., & Charron E. (2019). Anisotropy control in photoelectron spectra: A coherent two-pulse interference strategy. Phys. Rev. A, 100, 033402.
Résumé: Coherence among rotational ion channels during photoionization is exploited to control the anisotropy of the resulting photoelectron angular distributions at specific photoelectron energies. The strategy refers to a robust and single parameter control using two ultrashort light pulses delayed in time. The first pulse prepares a superposition of a few ion rotational states, whereas the second pulse serves as a probe that gives access to a control of the molecular asymmetry parameter β for individual rotational channels. This is achieved by tuning the time delay between the pulses, leading to channel interferences that can be turned from constructive to destructive. The illustrative example is the ionization of the E(1Σg+) state of Li2. Quantum wave-packet evolutions are conducted including both electronic and nuclear degrees of freedom to reach angle-resolved photoelectron spectra. A simple interference model based on coherent phase accumulation during the field-free dynamics between the two pulses is precisely exploited to control the photoelectron angular distributions from almost isotropic to marked anisotropic.
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Chin, A. W., Mangaud, E., Chevet, V., Atabek, O., & Desouter-Lecomte, M. (2019). Visualising the role of non-perturbative environment dynamics in the dissipative generation of coherent electronic motion. Chemical Physics, 525, 110392.
Résumé: Targeted exciton transport is crucial for efficient light-harvesting, but its microscopic description in biological systems is complicated by strong environmental coupling, highly structured vibrational environments and non-Markovian open system dynamics. In this article we employ the non-perturbative hierarchical equations of motion (HEOM) technique to explore how structured environments and tuned electronic properties can lead to the generation of coherent motion across a directed transport network, i.e. one containing an energy gradient. By further exploiting the information contained in the auxiliary HEOM matrices, we also visualize the complete displacement distributions of the main reaction coordinate during the ultrafast relaxation, and show that highly non-Gaussian profiles emerge when the electronic dynamics become quasi-reversible and involve bath-induced delocalized states. These coherent dynamics are spontaneously generated by earlier incoherent relaxation events, and we also demonstrate the correlation between the environmental coordinates and a quantitative volume-based measure of non-Markovianity.
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Coudert, L. H., Billard, F., Hertz, E., Faucher, O., & Lavorel, B. (2019). Torsional control of the methyl group in methanol. Physical Review A, 100(4), 043425.
Résumé: Experimental and theoretical investigations of the field-free alignment of the nonrigid methanol molecule are reported. The molecule is subject to a 140−TW/cm^2-intensity laser pulse with a 100-fs duration. The experimental signal displays a constant permanent alignment and a fast decaying transient alignment consistent with a prolatelike molecule with (B+C)/2 on the order of 0.808 cm^{−1}. The theoretical model takes into account the large-amplitude internal rotation of the methyl group with respect to the hydroxyl group. In the case of a continuous-wave laser field, a rotational alignment close to that of a rigid molecule is predicted. Torsional alignment also occurs even though there is no explicit dependence of the polarizability tensor on the angle of internal rotation. In the case of a strong short laser pulse, the theoretical approach shows that permanent and transient rotational alignment take place. The latter displays an exponential-like decay due to the high density of rotation-torsion levels. Torsional alignment also occurs and depends on the temperature. The theoretical model allows us to reproduce the experimental signal provided one component of the polarizability tensor is adjusted and dissipation effects due to molecular collisions are taken into account.
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Coudert, L. H., Margulès, L., Vastel, C., Motiyenko, R., Caux, E., & Guillemin, J. - C. (2019). Astrophysical detections and databases for the mono deuterated species of acetaldehyde CH2DCOH and CH3COD⋆. A&A, 624, A70.
Résumé: Context. Detection of deuterated species may provide information on the evolving chemistry in the earliest phases of star-forming regions. For molecules with two isomeric forms of the same isotopic variant, gas-phase and solid-state formation pathways can be differentiated using their abundance ratio.
Aims. Spectroscopic databases for astrophysical purposes are built for the two mono deuterated isomeric species CH2DCOH and CH3COD of the complex organic molecule acetaldehyde. These databases can be used to search and detect these two species in astrophysical surveys, retrieving their column density and therefore abundances.
Methods. Submillimeter wave and terahertz transitions were measured for mono deuterated acetaldehyde CH2DCOH which is a non-rigid species displaying internal rotation of its asymmetrical CH2D methyl group. An analysis of a dataset consisting of previously measured microwave data and the newly measured transition was carried out with a model accounting for the large amplitude torsion.
Results. The frequencies of 2556 transitions are reproduced with a unitless standard deviation of 2.3 yielding various spectroscopic constants. Spectroscopic databases for astrophysical purposes were built for CH2DCOH using the results of the present analysis and for CH3COD using the results of a previous spectroscopic investigation. These two species were both searched for and are detected toward a low-mass star-forming region.
Conclusions. We report the first detection of CH2DCOH (93 transitions) and the detection of CH3COD (43 transitions) species in source B of the IRAS 16293−2422 young stellar binary system located in the ρ Ophiuchus cloud region, using the publicly available ALMA Protostellar Interferometric Line Survey.
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Crépin-Gilbert, C., & Savchenko, E. (2019). Nanostructures and impurity centers in cryogenic environment. Low Temperature Physics, 45(6), 581–582.
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Cutrone G, Q. J., Menendez-Miranda M, Casas-Solvas JM, Aykaç A, Li X, Foulkes D, Moreira-Alvarez B, Encinar JR, Ladavière C, Desmaële D, Vargas-Berenguel A, Gref R. (2019). Comb-like dextran copolymers: A versatile strategy to coat highly porous MOF nanoparticles with a PEG shell. Carbohydr Polym, 223, 115085.
Résumé: Nanoparticles made of metal-organic frameworks (nanoMOFs) are becoming of increasing interest as drug carriers. However, engineered coatings such as poly(ethylene glycol) (PEG) based ones are required to prevent nanoMOFs recognition and clearance by the innate immune system, a prerequisite for biomedical applications. This still presents an important challenge due to the highly porous structure and degradability of nanoMOFs. We provide here a proof of concept that the surface of iron-based nanoMOFs can be functionalized in a rapid, organic solvent-free and non-covalent manner using a novel family of comb-like copolymers made of dextran (DEX) grafted with both PEG and alendronate (ALN) moieties, which are iron complexing groups to anchor to the nanoMOFs surface. We describe the synthesis of DEX-ALN-PEG copolymers by click chemistry, with control of both the amount of PEG and ALN moieties. Stable DEX-ALN-PEG coatings substantially decreased their internalization by macrophages in vitro, providing new perspectives for biomedical applications.
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Dartois, E., Chabot, M., Id Barkach, T., Rothard, H., Augé, B., Agnihotri, A. N., Domaracka, A., & Boduch, P. (2019). Non-thermal desorption of complex organic molecules. A&A, 627.
Résumé: Context. The occurrence of complex organic molecules (COMs) in the gas phase at low temperature in the dense phases of the interstellar medium suggests that a non-thermal desorption mechanism is at work because otherwise, COMs should condense within a short timescale onto dust grains. Vacuum ultraviolet (VUV) photodesorption has been shown to be much less efficient for complex organic molecules, such as methanol, because mostly photoproducts are ejected. The induced photolysis competes with photodesorption for large COMs, which considerably lowers the efficiency to desorb intact molecules.
Aims. We pursue an experimental work that has already shown that water molecules, the dominant ice mantle species, can be efficiently sputtered by cosmic rays. We investigate the sputtering efficiency of complex organic molecules that are observed either in the ice mantles of interstellar dense clouds directly by infrared spectroscopy (CH3OH), or that are observed in the gas phase by millimeter telescopes (CH3COOCH3) and that could be released from interstellar grain surfaces.
Methods. We irradiated ice films containing complex organic molecules (methanol and methyl acetate) and water with swift heavy ions in the electronic sputtering regime. We monitored the infrared spectra of the film as well as the species released to the gas phase with a mass spectrometer.
Results. We demonstrate that when methanol or methyl acetate is embedded in a water-ice mantle exposed to cosmic rays, a large portion is sputtered as an intact molecule, with a sputtering yield close to that of the main water-ice matrix. This must be even more true for the case of more volatile ice matrices, such as those that are embedded in carbon monoxide.
Conclusions. Cosmic rays penetrating deep into dense clouds provide an efficient mechanism to desorb complex organic molecules. Compared to the VUV photons, which are induced by the interaction of cosmic rays, a large portion desorb as intact molecules with a proportion corresponding to the time-dependent bulk composition of the ice mantle, the latter evolving with time as a function of fluence due to the radiolysis of the bulk.
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de Pujo, P., Ryan, M., Crépin, C., Mestdagh, J. M., & McCaffrey, J. G. (2019). The role of spin-orbit coupling in the optical spectroscopy of atomic sodium isolated in solid xenon. Low Temperature Physics, 45(7), 715–720.
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Declerck, V., Perez-Mellor, A., Guillot, R., Aitken, D. J., Mons, M., & Zehnacker, A. (2019). Vibrational circular dichroism as a probe of solid-state organisation of derivatives of cyclic beta-amino acids: Cis- and trans-2-aminocyclobutane-1-carboxylic acid. Chirality, 31(8), 547–560.
Résumé: Peptide models built from cis- and trans-2-aminocyclobutane-1-carboxylic acids (ACBCs) are studied in the solid phase by combining Fourier-transform infrared spectroscopy (FTIR) absorption spectroscopy, vibrational circular dichroism (VCD), and quantum chemical calculations using density functional theory (DFT). The studied systems are N-tert-butyloxycarbonyl (Boc) derivatives of 2-aminocyclobutanecarboxylic acid (ACBC) benzylamides, namely Boc-(cis-ACBC)-NH-Bn and Boc-(trans-ACBC)-NH-Bn. These two diastereomers show very different VCD signatures and intensities, which of the trans-ACBC derivative being one order of magnitude larger in the region of the nu (CO) stretch. The spectral signature of the cis-ACBC derivative is satisfactorily reproduced by that of the monomer extracted from the solid-state geometry of related ACBC derivatives, which shows that no long-range effects are implicated for this system. In terms of hydrogen bonds, the geometry of this monomer is intermediate between the C6 and C8 structures (exhibiting a 6- or 8-membered cyclic NHMIDLINE HORIZONTAL ELLIPSISO hydrogen bond) previously evidenced in the gas phase. The benzyl group must be in an extended geometry to reproduce satisfactorily the shape of the VCD spectrum in the nu (CO) range, which qualifies VCD as a potential probe of dispersion interaction. In contrast, reproducing the IR and VCD spectrum of the trans-ACBC derivative requires clusters larger than four units, exhibiting strong intermolecular H-bonding patterns. A qualitative agreement is obtained for a tetramer, although the intensity enhancement is not reproduced. These results underline the sensitivity of VCD to the long-range organisation in the crystal.
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Devolder, A., Luc-Koenig, E., Atabek, O., Desouter-Lecomte, M., & Dulieu, O. (2019). Laser-assisted self-induced Feshbach resonance for controlling heteronuclear quantum gas mixtures. Phys. Rev. A, 100(5), 052703.
Résumé: We propose a type of Feshbach resonance occurring when two different ultracold atoms in their ground state undergo an s-wave collision in the presence of a laser. The collisional levels of the atom pair are coupled by the laser to a rovibrational molecular level of the same electronic ground state: We name it a laser-assisted self-induced Feshbach resonance. This mechanism, valid for all heteronuclear quantum gas mixtures, is analyzed on the example of ultracold 87Rb and 84Sr atoms for which the resonant laser frequency falls in the subterahertz range. The interspecies scattering length can be controlled with the laser frequency and intensity without atom loss. Moreover, chirping slowly, the frequency allows for the adiabatic formation of ultracold 87Rb84Sr molecules in a manner very similar to a magnetic Feshbach resonance. A stimulated Raman adiabatic passage follows for stabilizing the molecules in their rovibronic ground state.
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Gans, B., Boyé-Péronne, S., & Liévin, J. (2019). Vibronic structure of the cyanobutadiyne cation. II. Theoretical exploration of the complex energy landscape of HC5N+. The Journal of Chemical Physics, 150(24), 244303.
Résumé: The results of an extensive ab initio study of the cyanobutadiyne cation, initially motivated by threshold-photoelectron spectroscopy experiments [see the study by Gans et al., J. Chem. Phys. 150, 244304 (2019)], are reported in the present paper. Calculations at the internally contracted multireference configuration interaction level of theory have been performed to derive the rovibronic properties of the seven lowest electronic states of HC5N+. Equilibrium geometries, rotational constants, vibrational frequencies, electric dipole moments, and spin-orbit constants have been calculated and compared with experimental data when available. Adiabatic and vertical ionization energies from the neutral ground state as well as transition energies within the cation electronic manifold are predicted, using the convergence to the complete basis set limit. The accurate description of the complex energy landscape up to 32 000 cm−1 above the ionization potential allows us to perform Franck-Condon simulations of the photoionization spectrum to the X+ 2Π, A+ 2Π, B+ 2Σ+, and C+ 2Π states and allows us to simulate the A+ 2Π → X+ 2Π emission spectrum. The vibronic perturbations occurring on the excited potential energy surfaces are revealed and discussed, in particular, for the 3 2Π surface, which presents a double-well topography.
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Gans, B., Garcia, G. A., Boyé-Péronne, S., Pratt, S. T., Guillemin, J. - C., Aguado, A., Roncero, O., & Loison, J. - C. (2019). Origin band of the first photoionizing transition of hydrogen isocyanide. Phys. Chem. Chem. Phys., 21, 2337–2344.
Résumé: The photoelectron spectrum of the X1Σ+ → X+2Σ+ ionizing transition of hydrogen isocyanide (HNC) is measured for the first time at a fixed photon energy (13 eV). The assignment of the spectrum is supported by wave-packet calculations simulating the photoionization transition spectrum and using ab initio calculations of the potential energy surfaces for the three lowest electronic states of the cation. The photoelectron spectrum allows the retrieval of the fundamental of the CN stretching mode of the cationic ground state ([small nu, Greek, tilde]3 = 2260 ± 80 cm−1) and the adiabatic ionization energy of hydrogen isocyanide: IE(HNC) = 12.011 ± 0.010 eV, which is far below that of HCN (IE(HCN) = 13.607 eV). In light of this latter result, the thermodynamics of the HCN+/HNC+ isomers is discussed and a short summary of the values available in the literature is given.
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Gans, B., Lamarre, N., Guillemin, J. - C., Douin, S., Alcaraz, C., Romanzin, C., Garcia, G. A., Liévin, J., & Boyé-Péronne, S. (2019). Vibronic structure of the cyanobutadiyne cation. I. VUV photoionization study of HC5N. The Journal of Chemical Physics, 150(24), 244304.
Résumé: We report the vacuum-ultraviolet threshold-photoelectron spectrum of HC5N recorded over a wide spectral range, from 84 000 to 120 000 cm−1, with a 120 cm−1 spectral resolution, better than what was achieved in previous photoelectron studies, and with mass selectivity. The adiabatic ionization potential of cyanobutadiyne is measured at 85 366 (±40) cm−1. Assignment of the vibrational bands of the four lowest electronic states X+2Π, A+2Π, B+2Σ+, and C+2Π are performed, supported by high level ab initio calculations which are fully detailed in Paper II [B. Gans et al., J. Chem. Phys. 150, 244303 (2019)] and by Franck-Condon simulations. Only vibrational stretching modes are observed in the threshold-photoelectron spectra. The ground state of HC5N+ exhibits a vibrational progression in the ν2 stretching mode involving mainly the elongation of the C≡C triple bonds, whereas the A+ and C+ excited electronic states show a progression in the stretching mode mainly associated with the elongation of the C≡N bond, i.e., ν4 and ν3, respectively. The B+ state appears almost as a vibrationless structure in close vicinity to the A+ state.
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Gonon, B., Lasorne, B., Karras, G., Joubert-Doriol, L., Lauvergnat, D., Billard, F., Lavorel, B., Faucher, O., Guerin, S., Hertz, E., & Gatti, F. (2019). A generalized vibronic-coupling Hamiltonian for molecules without symmetry: Application to the photoisomerization of benzopyran. J Chem Phys, 150(12), 124109.
Résumé: We present a model for the lowest two potential energy surfaces (PESs) that describe the photoinduced ring-opening reaction of benzopyran taken as a model compound to study the photochromic ring-opening reaction of indolinobenzospiropyran and its evolution toward its open-chain analog. The PESs are expressed in terms of three effective rectilinear coordinates. One corresponds to the direction between the equilibrium geometry in the electronic ground state, referred to as the Franck-Condon geometry, and the minimum of conical intersection (CI), while the other two span the two-dimensional branching space at the CI. The model correctly reproduces the topography of the PESs. The ab initio calculations are performed with the extended multiconfiguration quasidegenerate perturbation theory at second order method. We demonstrate that accounting for electron dynamic correlation drastically changes the global energy landscape since some zwitterionic states become strongly stabilized. Quantum dynamics calculations using this PES model produce an absorption spectrum that matches the experimental one to a good accuracy.
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Grazon, C., Si, Y., Placial, J. - P., Rieger, J., Méallet-Renault, R., & Clavier, G. (2019). Core–shell polymeric nanoparticles comprising BODIPY and fluorescein as ultra-bright ratiometric fluorescent pH sensors. Photochem. Photobiol. Sci., 18(5), 1156–1165.
Résumé: A new ratiometric fluorescent pH nanosensor is presented. It is based on ultrabright nanoparticles containing two spatially separated fluorophores: BODIPY covalently linked to the polystyrene core and fluorescein grafted to the nanoparticle shell. The nanoparticles comprise a large number (≥2500) of both fluorescent moieties. Their spectroscopic characteristics were studied at different pH and ionic strength. They could successfully be used to determine the solution pH between 5.5 and 7.5 by measuring the fluorescence intensity ratio of the sensor molecule (fluorescein) relative to the reference dye (BODIPY).
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Gruet, S., & Pirali, O. (2019). Far-infrared spectroscopy of heavy protonated noble gas species using synchrotron radiation. Molecular Physics, in press, 1–13.
Résumé: In this work, we report new absorption spectra of protonated noble gas species ArH+, KrH+ and XeH+. Both pure rotation transitions and rotation-vibration transitions were recorded at high resolution using the Fourier transform interferometer of the AILES beamline of the synchrotron facility SOLEIL. The species were produced in a ?hollow cathode? discharge cell for which the cathode is cooled down to liquid nitrogen temperature. While our spectra of ArH+ do not provide new experimental information compared to the wealth of data available in the literature, both spectra of KrH+ and XeH+ contain numerous new transitions belonging to several isotopologues observed in natural abundance. KrH+ and XeH+ spectra have been analysed using a Dunham Hamiltonian to provide mass independent sets of parameters and allowing to determine bond lengths with improved accuracy.
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Gruet, S., & Pirali, O. (2019). Far-infrared spectroscopy of heavy protonated noble gas species using synchrotron radiation. Molecular Physics, 117(13), 1719–1731.
Résumé: In this work, we report new absorption spectra of protonated noble gas species ArH+, KrH+ and XeH+. Both pure rotation transitions and rotation-vibration transitions were recorded at high resolution using the Fourier transform interferometer of the AILES beamline of the synchrotron facility SOLEIL. The species were produced in a ‘hollow cathode’ discharge cell for which the cathode is cooled down to liquid nitrogen temperature. While our spectra of ArH+ do not provide new experimental information compared to the wealth of data available in the literature, both spectra of KrH+ and XeH+ contain numerous new transitions belonging to several isotopologues observed in natural abundance. KrH+ and XeH+ spectra have been analysed using a Dunham Hamiltonian to provide mass independent sets of parameters and allowing to determine bond lengths with improved accuracy.
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Gruet, S., Pirali, O., Steber, A. L., & Schnell, M. (2019). The structural determination and skeletal ring modes of tetrahydropyran. Phys. Chem. Chem. Phys., 21, 3016–3023.
Résumé: A high-resolution molecular spectroscopy study was carried out on the cyclic ether tetrahydropyran (THP), one of the smallest molecules composed of a pyranose ring. As this ring structure is closely related to carbohydrates, THP can offer relevant insight into structural variations of this unit. Thus, an extensive probe of THP using three broadband instruments ranging from the microwave to the far-infrared (2–8 GHz, 75–110 GHz and 100–650 cm−1 frequency ranges) was performed to accrue both accurate sets of rotational constants and structural information. This array of experimental setups provided an accurate set of data to improve the description of the ground state of THP and revise the principal parameters of its backbone structure. The structural information was deduced from the assignment of the 13C and 18O isotopologues present in natural abundance. In addition, the complementary dataset obtained from these experiments led to a better characterization of the vibrational motions involving the skeletal ring of the molecule. In particular, the vibrational frequencies of four of these modes (ν23 (∼250 cm−1), ν22 (∼403 cm−1), ν21 (∼430 cm−1), and ν20 (∼562 cm−1)) have been determined from the analysis of the first rotationally resolved vibrational spectrum reported for THP. Quantum-chemical calculations aided in the analysis of the experimental results.
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Gutiérrez-Quintanilla A., Chevalier M., Platakyte R., Ceponkus J., & Crépin C. (2019). Selective photoisomerisation of 2- chloromalonaldehyde. J Chem Phys, 150, 034305.
Résumé: Isomerization of 2-chloromalonaldehyde (2-ClMA) is explored giving access to new experimental data on this derivative of malonaldehyde,
not yet studied much. Experiments were performed isolating 2-ClMA in argon, neon, and para-hydrogen matrices.
UV irradiation of the matrix samples induced isomerization to three open enolic forms including two previously observed along
with the closed enolic form after deposition. IR spectra of these specific conformers were recorded, and a clear assignment
of the observed bands was obtained with the assistance of theoretical calculations. UV spectra of the samples were measured,
showing a blue shift of the absorption with the opening of the internal hydrogen bond of the most stable
enol form. Specific sequences of UV irradiation at different wavelengths allowed us to obtain samples containing only one
enol conformer. The formation of conformers is discussed. The observed selectivity of the process among the enol forms is
analyzed.
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Gutiérrez-Quintanilla,, Briant,, Mengesha,, Gaveau, M. - A., Mestdagh,, Soep,, & Poisson,. (2019). Propyne-water complexes hosted in helium droplets. Low Temperature Physics, 45(6), 634–638.
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Harper, O. J., Hassenfratz, M., Loison, J. - C., Garcia, G. A., de Oliveira, N., Hrodmarsson, H. R., Pratt, S. T., Boyé-Péronne, S., & Gans, B. (2019). Quantifying the photoionization cross section of the hydroxyl radical. The Journal of Chemical Physics, 150(14), 141103.
Résumé: The hydroxyl free radical, OH, is one of the most important radicals in atmospheric and interstellar chemistry, and its cation plays a role in the reactions leading to H2O formation. Knowledge of the photoionization efficiency of the OH radical is crucial to properly model the water photochemical cycle of atmospheres and astrophysical objects. Using a gas-phase radical source based on a single H-abstraction reaction combined with a photoelectron/photoion imaging coincidence spectrometer coupled with synchrotron radiation, we recorded the OH+ photoion yield over the 12.6–15 eV energy range, and we set it to an absolute cross section scale using an absolute point measurement performed at 13.8eV: σion=9.0±2.7Mb. The resulting cross section values differ by approximately a factor 2 from the recent measurement of Dodson et al. [J. Chem. Phys. 148, 184302 (2018)] performed with a different radical source, which is somewhat greater than the combined uncertainties of the measurements. This finding underlines the need for further investigations of this cross section.
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Hrodmarsson, H. R., Loison, J. C., Jacovella, U., Holland, D. M. P., Boyé-Péronne, S., Gans, B., Garcia, G. A., Nahon, L., & Pratt, S. T. (2019). Valence-Shell Photoionization of C4H5: the 2-Butyn-1-yl Radical. J. Phys. Chem. A, 123, 1521–1528.
Résumé: We present new high-resolution data on the photoionization of the 2-butyn-1-yl radical (CH3CC •CH2) formed by H-atom abstraction from 2-butyne by F atoms. The spectra were recorded from 7.7 to 11 eV by using double-imaging, photoelectron-photoion coincidence spectroscopy, which allows the unambiguous correlation of photoelectron data and the mass of the species. The photoionization spectrum shows significant resonant autoionizing structure converging to excited states of the C4H5+ cation, similar to what is observed in the closely related propargyl radical (HCC •CH2). The threshold photoelectron spectrum, obtained with a resolution of 17 meV, is also reported. This spectrum is consistent with previous measurements of the first photoionization band, but has been extended to higher energy to allow the observation of bands corresponding to excited electronic states of the ion. A refined value of the adiabatic ionization energy is extracted: IE(C4H5) = 7.93 +/- 0.01 eV. A determination of the absolute photoionization cross section of the 2-butyn-1-yl radical at 9.7 eV is also reported:sigma(ion)(C4H5) = 6.1 +/- 1.8 Mb.
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Hrodmarsson, H. R., Garcia, G. A., Nahon, L., Gans, B., & Loison, J. - C. (2019). Threshold Photoelectron Spectrum of the Anilino Radical. The Journal of Physical Chemistry A, 123(42), 9193–9198.
Résumé: We report on the photoionization of the resonance-stabilized anilino radical (C6H5NH) formed by H atom abstraction from aniline by F atoms in a flow tube. The spectra were recorded from 7.8 to 9.7 eV by using a double-imaging photoelectron/photoion coincidence spectrometer with VUV radiation provided by the DESIRS beamline at the SOLEIL synchrotron. The vibrationally resolved recorded threshold photoelectron spectrum of the anilino radical showed transitions to the ground X+1A′ ← X2A″ and first excited states a+3A″ ← X2A″ of the cation, which were assigned through comparison with theoretically simulated spectra, yielding an adiabatic ionization energy of 8.02 ± 0.02 eV. These results are discussed in light of existing data on the picolyl structural isomers and are of interest for the analytical applications of coincidence techniques in real-time combustion analysis where these intermediates are found.
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Hrodmarsson, H. R., Garcia, G. A., Nahon, L., Loison, J. - C., & Gans, B. (2019). The absolute photoionization cross section of the mercapto radical (SH) from threshold up to 15.0 eV. Phys. Chem. Chem. Phys., 21, 25907.
Résumé: We present the absolute photoionization cross-section of the mercapto radical, SH, recorded from its first ionization energy at 10.4 eV up to a photon energy of 15 eV. The absolute scale was calibrated at the fixed photon energy of 11.2 eV using the known values of H2S and S as references. SH and S were produced in a microwave discharge flow-tube reactor by hydrogen abstraction of the H2S precursor. The measured photoionization cross-section of SH dramatically differs from the one currently employed to model the presence of this species in a number of astronomical environments, where SH along with its ionic counterpart SH+ have been detected. The cation spectroscopy and fragmentation of H2S, SH and S in the 9.2–15.0 eV energy range obtained using threshold photoelectron techniques is also presented and discussed in the context of existing literature.
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Hrodmarsson, H. R., Thissen, R., Dowek, D., Garcia, G. A., Nahon, L., & Govers, T. R. (2019). Isotope Effects in the Predissociation of Excited States of N2 (+) Produced by Photoionization of (14)N2 and (15)N2 at Energies Between 24.2 and 25.6 eV. Front Chem, 7(222).
Résumé: Photoelectron/photoion imaging spectrometry employing dispersed VUV radiation from the SOLEIL synchrotron has been used to study the predissociation of N2 (+) states located up to 1.3 eV above the ion's first dissociation limit. Branching ratios for unimolecular decay into either N2 (+) or N(+) were obtained by measuring coincidences between threshold electrons and mass-selected product ions, using a supersonic beam of either (14)N2 or (15)N2 as photoionization target. The results confirm that predissociation of the C 2 Sigma u + state of (14)N2 (+) is faster than emission to the electronic ground-state by a factor 10 or more for all vibrational levels v' >/= 3, while for (15)N2 (+) the two decay modes have comparable probabilities for the levels v' = 3, 4, and 5. In contrast, no significant isotope effect could be observed for the other states of N2 (+) identified in the photoelectron spectrum. For both (14)N2 (+) and (15)N2 (+) isotopologues all vibrational levels of these other states decay to an extent of at least 95% by predissociation.
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IdBarkach, T., Chabot, M., Béroff, K., Della Negra, S., Lesrel, J., Geslin, F., Le Padellec, A., Mahajan, T., & Díaz-Tendero, S. (2019). Breakdown curves of CH2(+), CH3(+), and CH4(+) molecules. A&A, 628.
Résumé: Aims. The aim of this work is to furnish branching ratios (BRs) to the kinetic databases used in astrochemistry such as the KInetic Database for Astrochemistry (KIDA). This concerns CHy(+) species (y = 2–4) excited by cosmic rays, electrons and photons, or the intermediate excited complexes CHy(+) resulting from a chemical reaction.
Methods. The full set of fragmentation branching ratios following CHy(+) (y = 2,4) of constant velocity (250 keV uma−1) colliding with He atoms has been measured with the multidetector AGAT. Kinetic energy distributions of neutral fragments produced in each dissociation channel have been also measured. With these experimental inputs, and theoretical dissociation energies, semiempirical breakdown curves (BDCs) have been constructed.
Results. Prediction of BRs with the present BDCs is found to agree with available BR measurements for electronic dissociative recombination, collision with fast electron and photodissociation. Dependence of BRs with the various UV fields relevant to interstellar medium and planetary atmospheres is predicted.
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Ilyushin, V., Armieieva, I., Dorovskaya, O., & et al. (2019). The torsional fundamental band and high-J rotational spectra of the ground, first and second excited torsional states of acetone. JOURNAL OF MOLECULAR SPECTROSCOPY, 363, 111169.
Résumé: We present a new global study of the millimeter, submillimeter and far-infrared (FIR) spectra involving the three lowest torsional states of acetone ((CH3)2CO). New microwave measurements have been carried out between 34 and 940 GHz using spectrometers in IRA NASU (Ukraine), and PhLAM Lille (France). The FIR spectrum of acetone has been recorded on the AILES beamline of the SOLEIL synchrotron facility. The new data involving torsion–rotation transitions with J up to 90 and Ka up to 52 were combined with previously published measurements and analyzed using a model developed recently to study the high resolution spectra of molecules with two equivalent methyl rotors and C2v symmetry at equilibrium (PAMC2v2tops program). The final fit included 117 parameters to give an overall weighted root-mean-square deviation of 0.85 for the dataset consisting of 29,584 microwave and 1116 FIR line frequencies belonging, respectively, to the three lowest torsional states (ν12,ν17) = (0,0), (1,0), (0,1) and to the observed fundamental band associated with the methyl-top torsion mode (ν12,ν17) = (0,1) ← (0,0). The high values of rotational quantum numbers involved in this study provide an opportunity to test the performance of the PAMC2v2tops program approach for the case of highly excited rotational states.
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Jian Xu, L. W., Tao Guo, Guoqing Zhang, Caifen Wang, Haiyan Li, Xue Li, Vikramjeet Singh, Weidong Chen, Ruxandra Gref, Jiwen Zhang. (2019). A “Ship-in-a-Bottle” strategy to create folic acid nanoclusters inside the nanocages of gamma-cyclodextrin metal-organic frameworks. Int J Pharm, 556, 89.
Résumé: Assembled between gamma-cyclodextrins (CD) and potassium ions, gamma-cyclodextrin metal-organic frameworks (CD-MOF) create spatially extended and ordered cage-like structures. Herein, it was demonstrated that folic acid (FA), a model molecule, could be densely packed inside CD-MOF reaching 2:1 FA:CD molar ratio. This “Ship-in-a-Bottle” strategy leads to a 1450 fold increase of the apparent solubility of FA. Moreover, the bioavailability of FA inside CD-MOF in rats was enhanced by a factor of 1.48 as compared to free FA. The unique mechanism of FA incorporation in the CD-MOF 3D network was also explored, which was different from the conventional CD inclusion complexation. Taylor dispersion investigations indicated that FA was incorporated on the basis of a two-component model, which was further supported by a set of complementary methods, including SEM, XRPD, BET, SR-FTIR, SAXS and molecular simulation. The hypothesized mechanism suggested that: i) tiny FA nanoclusters formed inside the hydrophilic cavities and onto the surface of CD-MOF and ii) FA was included inside dual-CD units in CD-MOF. In a nutshell, this dual incorporation mechanism is an original approach to dramatically increase the drug apparent solubility and bioavailability, and could be a promising strategy for other poorly soluble drugs.
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Johansen, S. L., Martin-Drumel, M. - A., & Crabtree, K. N. (2019). Rotational Spectrum of the β-Cyanovinyl Radical: A Possible Astrophysical N-Heterocycle Precursor. The Journal of Physical Chemistry A, 123(24), 5171–5177.
Résumé: A fundamental question in the field of astrochemistry is whether the molecules essential to life originated in the interstellar medium (ISM), and, if so, how they were formed. Nitrogen-containing heterocycles are of particular interest because of their role in biology; however, to date, no N-heterocycle has been detected in the ISM, and it is unclear how and where such species might form. Recently, the β-cyanovinyl radical (HCCHCN) was implicated in the low-temperature gas-phase formation of pyridine. While neutral vinyl cyanide (H2CCHCN) has been rotationally characterized and detected in the ISM, HCCHCN has not. Here, we present the first theoretical study of all three cyanovinyl isomers at the CCSD(T)/ANO1 level of theory and the experimental rotational spectra of cis- and trans-HCCHCN, as well as those of their 15N isotopologues, from 5 to 75 GHz. The observed spectra are in good agreement with calculations and provide a basis for further laboratory and astronomical investigations of these radicals.
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Karman, T., Gordon, I. E., van der Avoird, A., Baranov, Y. I., Boulet, C., Drouin, B. J., Groenenboom, G. C., Gustafsson, M., Hartmann, J. - M., Kurucz, R. L., Rothman, L. S., Sun, K., Sung, K., Thalman, R., Tran, H., Wishnow, E. H., Wordsworth, R., Vigasin, A. A., Volkamer, R., & van der Zande, W. J. (2019). Update of the HITRAN collision-induced absorption section. Icarus, 328, 160–175.
Résumé: Correct parameterization of the Collision-induced Absorption (CIA) phenomena is essential for accurate modeling of planetary atmospheres. The HITRAN spectroscopic database provides these parameters in a dedicated section. Here, we significantly revise and extend the HITRAN CIA data with respect to the original effort described in Richard et al. [JQSRT 113, 1276 (2012)]. The extension concerns new collisional pairs as well as wider spectral and temperature ranges for the existing pairs. The database now contains CIA for N2-N2, N2-H2, N2-CH4, N2-H2O, N2-O2, O2-O2, O2-CO2, CO2-CO2, H2-H2, H2-He, H2-CH4, H2-H, H-He, CH4-CH4, CH4-CO2, CH4-He, and CH4-Ar collision pairs. The sources of data as well as their validation and selection are discussed. A wish list to eliminate remaining deficiencies or lack of data from the astrophysics perspective is also presented.
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Kleimeier, N. F., Wenzel, G., Urban, A. J., Tchalala, M. R., Oughaddou, H., Dedkov, Y., Voloshina, E., & Zacharias, H. (2019). Unoccupied electronic band structure of pentagonal Si nanoribbons on Ag(110). PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 21(32), 17811–17820.
Résumé: Silicon nanoribbons – one dimensional silicon structures with a pentagonal atomic structure and mixed sp(2)- and sp(3)-hybridisation – grow on Ag(110) upon deposition of silicon. These nanostructures are viewed as promising candidates for modern day electronics as they are comprised of the same element as today's semiconductor devices. Even though they have been studied extensively over the last decade, only little is known about their unoccupied band structure which is important for possible future optoelectronics, semiconductor, and spintronics applications. In order to elucidate the unoccupied band structure of the nanoribbons, k-resolved inverse photoemission spectroscopy (KRIPES) studies were performed on both nanoribbon structures reported in the literature as well as on the bare Ag(110) substrate within the energy range of E-EF = 0-6.5 eV. The obtained experimental results are compared to density functional theory (DFT) calculated band structures to assign individual spectral features to specific bands. Since even small changes in the structural model of the nanoribbons lead to a change in the calculated band structure, this comparison allows us to assess the validity of the proposed structural models.
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Lampin, J. - F., Pirali, O., Buchanan, Z. S., Eliet, S., Martin-Drumel, M. - A., Turut, J., Roy, P., Hindle, F., & Mouret, G. (2019). Broadband terahertz heterodyne spectrometer exploiting synchrotron radiation at megahertz resolution. Opt. Lett., 44(20), 4985–4988.
Résumé: A new spectrometer allowing both high resolution and broadband coverage in the terahertz (THz) domain is proposed. This instrument exploits the heterodyne technique between broadband synchrotron radiation and a quantum-cascade-laser-based molecular THz laser that acts as the local oscillator. Proof of principle for exploitation for spectroscopy is provided by the recording of molecular absorptions of hydrogen sulfide (H2S) and methanol (CH3OH) around 1.073 THz. Ultimately, the spectrometer will enable to cover the 1–4 THz region in 5 GHz windows at Doppler resolution.
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Latka, T., Shirvanyan, V., Ossiander, M., Razskazovskaya, O., Guggenmos, A., Jobst, M., Fieß, M., Holzner, S., Sommer, A., Schultze, M., Jakubeit, C., Riemensberger, J., Bernhardt, B., Helml, W., Gatti, F., Lasorne, B., Lauvergnat, D., Decleva, P., Halász, G., Vibók, A., & Kienberger, R. (2019). Femtosecond wave-packet revivals in ozone. Phys. Rev. A, 99(6), 063405.
Résumé: Photodissociation of ozone following absorption of biologically harmful solar ultraviolet radiation is the key mechanism for the life protecting properties of the atmospheric ozone layer. Even though ozone photolysis is described successfully by post-Hartree-Fock theory, it has evaded direct experimental access so far, due to the unavailability of intense ultrashort deep ultraviolet radiation sources. The rapidity of ozone photolysis with predicted values of a few tens of femtoseconds renders both ultrashort pump and probe pulses indispensable to capture this manifestation of ultrafast chemistry. Here, we present the observation of femtosecond time-scale electronic and nuclear dynamics of ozone triggered by ∼10-fs, ∼2-µJ deep ultraviolet pulses and, in contrast to conventional attochemistry experiments, probed by extreme ultraviolet isolated pulses. An electronic wave packet is first created. We follow the splitting of the excited B-state related nuclear wave packet into a path leading to molecular fragmentation and an oscillating path, revolving around the Franck-Condon point with 22-fs wave-packet revival time. Full quantum-mechanical ab initio multiconfigurational time-dependent Hartree simulations support this interpretation.
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Lee, K. L. K., Thorwirth, S., Martin-Drumel, M. - A., & McCarthy, M. C. (2019). Generation and structural characterization of Ge carbides GeCn (n = 4, 5, 6) by laser ablation, broadband rotational spectroscopy, and quantum chemistry. Phys. Chem. Chem. Phys., 21, 18911–18919.
Résumé: Following the recent discovery of T-shaped GeC2, rotational spectra of three larger Ge carbides, linear GeC4, GeC5, and GeC6 have been observed using chirped pulse and cavity Fourier transform microwave spectroscopy and a laser ablation molecule source, guided by new high-level quantum chemical calculations of their molecular structure. Like their isovalent Si-bearing counterparts, Ge carbides with an even number of carbon atoms beyond GeC2 are predicted to possess 1Σ ground electronic states, while odd-numbered carbon chains are generally 3Σ; all are predicted to be highly polar. For the three new molecules detected in this work, rotational lines of four of the five naturally occurring Ge isotopic variants have been observed between 6 and 22 GHz. Combining these measurements with ab initio force fields, the Ge–C bond lengths have been determined to high precision: the derived values of 1.776 Å for GeC4, 1.818 Å for GeC5, and 1.782 Å for GeC6 indicate a double bond between these two atoms. Somewhat surprisingly, the spectrum of GeC5 very closely resembles that of a 1Σ molecule, implying a spin–spin coupling constant λ in excess of 770 GHz for this radical, a likely consequence of the large spin–orbit constant of atomic Ge (∼1000 cm−1). A systematic comparison between the production of SiCn and GeCn chains by laser ablation has also been undertaken. The present work suggests that other large metal-bearing molecules may be amenable to detection by similar means.
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Li, X., Semiramoth, N., Hall, S., Tafani, V., Josse, J., Laurent, F., Salzano, G., Foulkes, D., Brodin, P., Majlessi, L., Ghermani, N. ‐E., Maurin, G., Couvreur, P., Serre, C., Bernet‐Camard, M. ‐F., Zhang, J., & Gref, R. (2019). Combinatorial Drug Therapy: Compartmentalized Encapsulation of Two Antibiotics in Porous Nanoparticles: an Efficient Strategy to Treat Intracellular Infections (Part. Part. Syst. Charact. 3/2019). Part. Part. Syst. Charact., 36(3), 1970009.
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Li, X., Semiramoth, N., Hall, S., Tafani, V., Josse, J., Laurent, F., Salzano, G., Foulkes, D., Brodin, P., Majlessi, L., Ghermani, N. ‐E., Maurin, G., Couvreur, P., Serre, C., Bernet‐Camard, M. ‐F., Zhang, J., & Gref, R. (2019). Compartmentalized Encapsulation of Two Antibiotics in Porous Nanoparticles: an Efficient Strategy to Treat Intracellular Infections. Part. Part. Syst. Charact., 36(3), 1800360.
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Ma, J., Zhang, H., Lavorel, B., Billard, F., Hertz, E., Boulet, C., Hartmann, J. M., & Faucher, O. (2019). Observing collisions beyond the secular approximation limit. Nat Commun, 10, 5780.
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Mahajan, T., Béroff, K., Pons, B., Illescas, C., Chabot, M., IdBarkach, T., Launoy, T., Le Padellec, A., Jallat, A., Jorge, A., Aguirre, N. F., & Diaz-Tendero, S. (2019). Excitation, ionization, neutralization and anionic production in collisions of C+, N+ and C n N+ (n = 1–3) with He atoms at 2.2 a.u. velocity; cross sections and dissociation branching ratios. Journal of Physics B: Atomic, Molecular and Optical Physics, 52(19), 195204.
Résumé: We present measurements of absolute cross sections for projectile ionization and electron capture for C+, N+ and CnN+ (n = 1–3) projectiles impinging on He atoms with velocity v = 2.2 a.u. Single and multiple electron processes are considered, as well as projectile dissociative excitation in the case of incident molecular cations. The measurements are compared to Classical Trajectory Monte Carlo (CTMC) calculations for C+, N+ + He collisions in the framework of the independent electron approximation. CnN+ + He systems are described by means of the independent atom and electron (IAE) model which represents the molecule as a set of independent atoms. The impact parameter probabilities for excitation, ionization and electron transfer in C, C+, N–He collisions, underlying the IAE calculations, are also obtained by means of CTMC computations. A good agreement is generally found between measured and calculated cross sections, except for anionic production of C− and CnN−. The internal energy deposit due to electron excitation in CnN+ is also calculated with the IAE/CTMC model and compared to semi-empirical estimates based on either measured dissociation branching ratios for C2N+ and C3N+ (IdBarkach et al 2018 Mol. Astrophys. 12 25) or measured fragments kinetic energy release for CN+. Finally, measured dissociation branching ratios of excited CnN− and CnNQ+ species, with 1 ≤ n ≤3 and 0 ≤ Q ≤ 4, are reported.
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Mangaud E, Lasorne B, Atabek, O., & Desouter-Lecomte M. (2019). Statistical distributions of the tuning and coupling collective modes at a conical intersection using the hierarchical equations of motion. J Chem Phys, 151(24), 244102.
Résumé: We investigate the possibility of extracting the probability distribution of the effective environmental tuning and coupling modes during the nonadiabatic relaxation through a conical intersection. Dynamics are dealt with an open quantum system master equation by partitioning a multistate electronic subsystem out of all the nuclear vibrators. This is an alternative to the more usual partition retaining the tuning and coupling modes of a conical intersection in the active subsystem coupled to a residual bath. The minimal partition of the electronic system generally leads to highly structured spectral densities for both vibrational baths and requires a strongly nonperturbative non-Markovian master equation, treated here by the hierarchical equations of motion (HEOMs). We extend-for a two-bath situation-the procedure proposed by Shi et al. [J. Chem. Phys. 140, 134106 (2014)], whereby the information contained in the auxiliary HEOM matrices is exploited in order to derive the nuclear dissipative wave packet, i.e., the statistical distribution of the displacement of the two tuning and coupling collective coordinates in each electronic state and the coherence. This allows us to visualize the distribution, all along the nonadiabatic decay. We explore a large parameter space for a symmetrical conical intersection model and a symmetrical initial Franck-Condon preparation. Some parameters could be controlled by external fields, while others are molecule dependent and could be designed by molecular engineering. We illustrate the relation between the strongly coupled electronic and bath dynamics together with a geometric measure of non-Markovianity.
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Mankos, M., Shadman, K., Hahn, R., Picard, Y. J., Comparat, D., Fedchenko, O., Schonhense, G., Amiaud, L., Lafosse, A., & Barrett, N. (2019). Design for a high resolution electron energy loss microscope. ULTRAMICROSCOPY, 207, 112848.
Résumé: An electron optical column has been designed for High Resolution Electron Energy Loss Microscopy (HREELM). The column is composed of electron lenses and a beam separator that are placed between an electron source based on a laser excited cesium atom beam and a time-of-flight (ToF) spectrometer or a hemispherical analyzer (HSA). The instrument will be able to perform full field low energy electron imaging of surfaces with sub-micron spatial resolution and meV energy resolution necessary for the analysis of local vibrational spectra. Thus, non-contact, real space mapping of microscopic variations in vibrational levels will be made possible. A second imaging mode will allow for the mapping of the phonon dispersion relations from microscopic regions defined by an appropriate field aperture.
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Mathurin, J., Dartois, E., Pino, T., Engrand, C., Duprat, J., Deniset-Besseau, A., Borondics, F., Sandt, C., & Dazzi, A. (2019). Nanometre-scale infrared chemical imaging of organic matter in ultra-carbonaceous Antarctic micrometeorites (UCAMMs). A&A, 622.
Résumé: Aims. The composition of comets and asteroids sheds light on the formation and early evolution of the solar system. The study of micrometeorites containing large concentrations of carbonaceous material (i.e. ultra-carbonaceous antarctic micrometeorites, UCAMMs) allows for unique information on the association of minerals and organics at surface of icy objects (comets) to be obtained.
Methods. In this work we map the organic matter of UCAMMs collected in the Antarctic snow, at sub-wavelength spatial scales using the Atomic Force Microscope InfraRed (AFMIR) technique. The sample preparation did not involve any chemical pretreatment to extract organic matter. The AFMIR measurements were performed on a limited spectral coverage (1900–1350 cm−1) allowing chemical functional groups to be imaged at spatial scales relevant to the study of micrometeorites.
Results. The AFMIR images reveal the variability of the functional groups at very small scales and the intimate association of carbon- and oxygen-bearing chemical bonds. We demonstrate the possibility to potentially separate the olefinic and aromatic C=C bonding in the subcomponents of the UCAMM fragment. These variations probably originate in the early mixing of the different reservoirs of organic matter constituting these dust particles. The measurements demonstrate the potential for analysing such complex organic-matter – mineral association at scales below the diffraction limit. The development of such studies and extension to the full infrared range spectral coverage will drive a new view on the vibrational infrared analysis of interplanetary material.
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McCarthy, M. C., Martin-Drumel, M. - A., Baraban, J., Changala, P. B., & Stanton, J. (2019). The hunt for elusive molecules: Insights from joint theoretical and experimental investigations. Chem. Eur. J., 25(30), 7243–7258.
Résumé: Rotational spectroscopy is an invaluable tool to unambiguously determine the molecular structure of a species, and sometimes even to establish its very existence. This article illustrates how experimental and theoretical state-of-the-art tools can be used in tandem to investigate the rotational structure of molecules, with particular emphasis on those that have long remained elusive. The examples of three emblematic species --- extit{gauche}-butadiene, disilicon carbide, and germanium dicarbide--- highlight the close, mutually beneficial interaction between high-level theoretical calculations and sensitive microwave measurements. Prospects to detect still other elusive molecules of chemical and astronomical interest are discussed.
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Mery, M., Gonzalez, C., García, C., Romero, C. P., Esaulov, V. A., & Valdés, J. E. (2019). Sputtering yields of tantalum by hydrogen ions in the energy range of 3–11 keV. RADIATION EFFECTS AND DEFECTS IN SOLIDS, 174(1-2), 2–8.
Résumé: The total sputtering yield of 6nm thick polycrystalline tantalum films resulting from H-2(+) ion bombardment, at normal incidence, has been determined. For this purpose, we study the evolution of the energy loss of protons transmitted through very thin films of tantalum following bombardment with controlled doses of H-2(+). The energy of the incident ions ranges from 3 to 11 keV. Our method allows us to determine how to find the limit of the thin film surface contamination which is important for stopping power measurements of pure samples. It also allows to prepare films of predetermined variable thickness.
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Ndengué, S. A., Scribano, Y., Benoit, D. M., Gatti, F., & Dawes, R. (2019). Intermolecular rovibrational bound states of H2O H2 dimer from a MultiConfiguration Time Dependent Hartree approach. Chemical Physics Letters, 715, 347–353.
Résumé: We compute the rovibrational eigenstates of the H2O-H2 Van der Waals complex using the accurate rigid-rotor potential energy surface of Valiron et al. (2008) with the MultiConfiguration Time Dependent Hartree (MCTDH) method. The rovibrational bound states calculations are done with the Block Improved Relaxation procedure of MCTDH and the subsequent assignment of the states is achieved by inspection of the wavefunctions’ properties. The results of this work are found to be in close agreement with previous time independent calculations reported for this complex and therefore supports the use of the MCTDH approach for the rovibrational spectroscopic study of such weakly bound complexes.
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Nguyen, H. L., Kumar, N., Audibert, J. - F., Ghasemi, R., Lefevre, J. - P., Ha-Thi, M. - H., Mongin, C., & Leray, I. (2019). Water-soluble aluminium fluorescent sensor based on aggregation-induced emission enhancement. New J. Chem., 43(38), 15302–15310.
Résumé: In the present work, we propose a new salicylaldehyde azine based water-soluble fluorescent sensor (PSSA – 4-propoxysulfonate salicylaldehyde azine) dedicated to aluminium(iii) detection in aqueous solutions. The introduction of sulfonate functional groups provides the probe with enhanced water-solubility, which is crucial for the direct analysis of polluted samples. We proved that aluminium(iii) complexation with PSSA in water induces an aggregation-induced emission enhancement (AIEE) process leading to the formation of well-defined dendritic structures which have been characterized by different analysis techniques (DLS, SEM, and FLIM). A limit of detection towards aluminium(iii) of 153 nM has been determined, which is more than one order of magnitude below the World Health Organization (WHO) guideline (≈3.7 μM). Moreover, satisfactory selectivity for this compound has been demonstrated over a large variety of metal cations. Finally, PSSA has been introduced into a digital microfluidic sensor chip, thus providing a sub-micromolar portable detection device devoted to aluminium(iii) polluted water samples.
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Odintsova, T. A., Tretyakov, M. Y., Zibarova, A. O., Pirali, O., Roy, P., & Campargue, A. (2019). Far-infrared self-continuum absorption of H216O and H218O (15–500 cm−1). Journal of Quantitative Spectroscopy and Radiative Transfer, 227, 190–200.
Résumé: The water vapor continuum absorption is studied in a spectral range covering most of the pure rotational spectrum of water molecule up to 500 cm−1. The continuum absorption was derived from the broadband water vapor spectra recorded by Fourier transform spectrometer equipped with the 151-m multipass gas cell at the AILES beam line of the SOLEIL synchrotron. The coherent (10–35 cm−1) and standard (40–500 cm−1) radiation modes of the synchrotron were used. In order to refine the magnitude and clarify the physical origin of the continuum, spectra of the two major water isotopologues, H216O and H218O, were considered. Recordings at several water vapor pressures were used to check the expected quadratic pressure dependence of the continuum. The new data extend and supplement previous measurements filling, in particular, the gap between 200 and 350 cm−1, which was never studied before. The H216O and H218O absorption continua in the range of 50–650 cm−1 show similar frequency dependence and magnitude. In particular, both continua exhibit a clear water dimer spectral signature near 15 cm−1, in good agreement with previous ab initio calculations. The present data confirm that the MT-CKD empirical continuum model widely used in atmospheric applications, overestimates importantly the continuum magnitude in the whole range of the rotational band. The observed irregular frequency dependence of the retrieved self-continuum cross-section values is tentatively interpreted as due to uncertainties on the resonance lines of the water monomer spectrum which is subtracted from the recorded spectra. On the basis of spectra simulations, the inadequate description of the line shapes in the range of the intermediate wings (detuning of 5–10 cm−1 from line center) and the uncertainties on the self-broadening coefficients of water monomer lines are identified as possible mechanisms responsible of the observed irregular fluctuations.
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Paille, G., Boulmier, A., Bensaid, A., Ha-Thi, M. - H., Tran, T. - T., Pino, T., Marrot, J., Rivière, E., Hendon, C. H., Oms, O., Gomez-Mingot, M., Fontecave, M., Mellot-Draznieks, C., Dolbecq, A., & Mialane, P. (2019). An unprecedented {Ni14SiW9} hybrid polyoxometalate with high photocatalytic hydrogen evolution activity. Chem. Commun., 55(29), 4166–4169.
Résumé: A unique polyoxometalate complex made up of a tetradecanuclear nickel bisphosphonate cluster capping a {SiW9} unit has been characterized. This stable compound exhibits a high hydrogen evolution reaction photocatalytic activity under visible light irradiation via a reductive quenching mechanism.
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Paille, G., Gomez-Mingot, M., Roch-Marchal, C., Haouas, M., Benseghir, Y., Pino, T., Ha-Thi, M. - H., Landrot, G., Mialane, P., Fontecave, M., Dolbecq, A., & Mellot-Draznieks, C. (2019). Thin Films of Fully Noble Metal-Free POM@MOF for Photocatalytic Water Oxidation. ACS Applied Materials & Interfaces, 11(51), 47837–47845.
Résumé: P2W18Co4@MOF-545, which contains the sandwich-type polyoxometalate (POM) [(PW9O34)2Co4(H2O)2]10– (P2W18Co4) immobilized in the porphyrinic metal–organic framework (MOF), MOF–545, is a “three-in-one” (porosity + light capture + catalysis) heterogeneous photosystem for the oxygen-evolution reaction (OER). Thin films of this composite were synthesized on transparent and conductive indium tin oxide (ITO) supports using electrophoretic (EP) or drop-casting (DC) methods, thus providing easy-to-use devices. Their electro- and photocatalytic activities for OER were investigated. Remarkably, both types of films exhibit higher turnover numbers (TONs) than the original bulk material previously studied as a suspension for the photocatalytic OER, with TONs after 2 h equal to 1600 and 403 for DC and EP films, respectively, compared to 70 for the suspension. This difference of catalytic activities is related to the proportion of efficiently illuminated crystallites, whereby a DC thin film offers the largest proportion of POM@MOF crystallites exposed to light due to its lower thickness when compared to an EP film or crystals in suspension. Such devices can be easily recycled by simply removing them from the reaction medium and washing them before reuse. The films were fully characterized with extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) spectroscopies, Raman, scanning electron microscopy, and electrochemistry before and after catalysis. The combination of all of these techniques shows the stability of both the POM and the MOF within the composite upon water-oxidation reaction.
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Perez-Mellor, A., Alata, I., Lepere, V., & Zehnacker, A. (2019). Conformational Study of the Jet-Cooled Diketopiperazine Peptide Cyclo Tyrosyl-Prolyl. Journal Of Physical Chemistry B, 123(28).
Résumé: The conformational landscape of the diketopiperazine (DKP) dipeptide built on tyrosine and proline, namely, cyclo Tyr-Pro, is studied by combining resonance-enhanced multiphoton ionization, double resonance infrared ultraviolet (IR-UV) spectroscopy, and quantum chemical calculations. Despite the geometrical constraints due the two aliphatic rings, DKP and proline, cyclo Tyr-Pro is a flexible molecule. For both diastereoisomers, cyclo LTyr-LPro and cyclo LTyr-DPro, two structural families coexist under supersonic jet conditions. In the most stable conformation, the aromatic tyrosine substituent is folded over the DKP ring (g(+) geometry of the aromatic ring) as it is in the solid state. The other structure is completely extended (g(-) geometry of the aromatic ring) and resembles that proposed for the vapor phase. IR-UV results are not sufficient for unambiguous assignment of the observed spectra to either folded or extended conformations and the simulation of the vibronic pattern of the S-0-S-1 transition is necessary. Still, the comparison between IR-UV results and anharmonic calculations allows explanation of the minor structural differences between cyclo LTyr-LPro and cyclo LTyr-DPro in terms of different NH center dot center dot center dot pi and CH center dot center dot center dot pi interactions.
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Pino, T., Chabot, M., Béroff, K., Godard, M., Fernandez-Villoria, F., Le, K. C., Breuer, L., Herder, M., Wucher, A., Bender, M., Severin, D., Trautmann, C., & Dartois, E. (2019). Release of large polycyclic aromatic hydrocarbons and fullerenes by cosmic rays from interstellar dust. A&A, 623.
Résumé: Context. Top-down chemistry is believed to be responsible for the formation of the large molecular compounds such as the polycyclic aromatic hydrocarbon-like molecules and the fullerenes observed in the interstellar medium. The release of these large molecules from the parent grains remains an important issue to be investigated.
Aims. Cosmic rays irradiate the dust grains during their journey in the interstellar medium. In this study we probe to what extent electronic sputtering and/or desorption processes induced by high-energy ion projectiles contribute to the creation of the large molecular component in space.
Methods. Carbonaceous dust analogues were produced in an ethylene flame. The resulting soot nanoparticles generated under well-defined conditions were irradiated by swift heavy ions, and mass spectra of the ionic and neutral molecular fragments emitted shortly after the impact were monitored.
Results. Large molecular fragments were detected, including neutral and ionic polycyclic aromatic hydrocarbons containing up to several tens of carbon atoms, as well as ionic fullerenes. Although the absolute efficiencies were not obtained, these experiments provide a proof of principle of a top-down scenario involving interaction processes of interstellar dust with high-energy projectiles yielding large molecular compounds observed in space.
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Platakyte, R., Gutiérrez-Quintanilla, A., Sablinskas, V., & Ceponkus, J. (2019). Influence of environment and association with water, to internal structure of trifluoroacetylacetone. Matrix isolation FTIR study. Low Temperature Physics, 45(6), 615–626.
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Pommier, D., Bretel, R., López, L. E. P., Fabre, F., Mayne, A., Boer-Duchemin, E., Dujardin, G., Schull, G., Berciaud, S., & Le Moal, E. (2019). Scanning Tunneling Microscope-Induced Excitonic Luminescence of a Two-Dimensional Semiconductor. Phys. Rev. Lett., 123(2), 027402.
Résumé: The long sought-after goal of locally and spectroscopically probing the excitons of two-dimensional (2D) semiconductors is attained using a scanning tunneling microscope (STM). Excitonic luminescence from monolayer molybdenum diselenide (MoSe2) on a transparent conducting substrate is electrically excited in the tunnel junction of an STM under ambient conditions. By comparing the results with photoluminescence measurements, the emission mechanism is identified as the radiative recombination of bright A excitons. STM-induced luminescence is observed at bias voltages as low as those that correspond to the energy of the optical band gap of MoSe2. The proposed excitation mechanism is resonance energy transfer from the tunneling current to the excitons in the semiconductor, i.e., through virtual photon coupling. Additional mechanisms (e.g., charge injection) may come into play at bias voltages that are higher than the electronic band gap. Photon emission quantum efficiencies of up to 10−7 photons per electron are obtained, despite the lack of any participating plasmons. Our results demonstrate a new technique for investigating the excitonic and optoelectronic properties of 2D semiconductors and their heterostructures at the nanometer scale.
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Porcino, M., Christodoulou, I., Vuong, M. D. L., Gref, R., & Martineau-Corcos, C. (2019). New insights on the supramolecular structure of highly porous core–shell drug nanocarriers using solid-state NMR spectroscopy. RSC Adv., 9(56), 89.
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Ramos Chagas, G., Morán Cruz, G., Méallet-Renault, R., Gaucher, A., Prim, D., Weibel, D. E., Amigoni, S., Guittard, F., & Darmanin, T. (2019). Superhydrophobic and fluorescent properties of fluorinated polypyrene surfaces using various polar linkers prepared via electropolymerization. Reactive and Functional Polymers, 135, 65–76.
Résumé: Superhydrophobic and fluorescent polypyrene surfaces were synthesized by an electropolymerization process. Six different linkers (ester, thioester, amide, carbamate, thiocarbamate and urea) are used to introduce fluorinated chains (lengths of 4, 6 and 8 carbons) onto pyrene moiety. The electropolymerized surfaces were analyzed by their morphology, surface chemistry, wettability and fluorescence. The linkers and the length of the fluorinated chain influence on both surface chemistry and morphology confirmed by XPS and SEM analysis, respectively. Superhydrophobic surfaces were obtained for ester, thioester, carbamate and thiocarbamate series while high hydrophobic surfaces for amide and urea series. Here, we show the possibility to control the surface hydrophobicity, oleophobicity and liquid adhesion with both the linker and the fluorinated chain length. For example, NH groups seem to induce a decrease in the static contact angle (θw) and in the surface structuration due to their polarity generating smoother surfaces (as for amide and urea series) and yielding to a red-shift in the emission spectra (showed for amide, carbamate, thiocarbamate and urea). The emission of all the polypyrene films is red-shifted compared to the pyrene monomers (excimer emission) and in the green region independently of the side chain. Here, we show that the nature of the heteroatom that connects the pyrene moiety to the fluorinated chain also does great impact on the surface morphology, wetting and fluorescence properties.
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Riemensberger, J., Neppl, S., Potamianos, D., Schaffer, M., Schnitzenbaumer, M., Ossiander, M., Schroder, C., Guggenmos, A., Kleineberg, U., Menzel, D., Allegretti, F., Barth, J. V., Kienberger, R., Feulner, P., Borisov, A. G., Echenique, P. M., & Kazansky A. K. (2019). Attosecond Dynamics of sp-Band Photoexcitation. Phys. Rev. Lett., 123(17), 176801.
Résumé: We report measurements of the temporal dynamics of the valence band photoemission from the magnesium (0001) surface across the resonance of the ¯Γ surface state at 134 eV and link them to observations of high-resolution synchrotron photoemission and numerical calculations of the time-dependent Schrödinger equation using an effective single-electron model potential. We observe a decrease in the time delay between photoemission from delocalized valence states and the localized core orbitals on resonance. Our approach to rigorously link excitation energy-resolved conventional steady-state photoemission with attosecond streaking spectroscopy reveals the connection between energy-space properties of bound electronic states and the temporal dynamics of the fundamental electronic excitations underlying the photoelectric effect.
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Rojas-Lorenzo,, Lara-Moreno,, Gutierrez-Quintanilla,, Chevalier,, & Crépin,. (2019). Theoretical study of “trapping sites” in cryogenic rare gas solids doped with β-dicarbonyl molecules. Low Temperature Physics, 45, 363–370.
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Rukmana, T. I., Moran, G., Méallet-Renault, R., Ohtani, M., Demura, T., Yasukuni, R., & Hosokawa, Y. (2019). Enzyme-Assisted Photoinjection of Megadalton Molecules into Intact Plant Cells Using Femtosecond Laser Amplifier. Scientific Reports, 9, 17530.
Résumé: Femtosecond laser photoporation has become a popular method to deliver various kinds of molecules such as genes, proteins, and fluorescent dyes into single mammalian cells. However, this method is not easily applied to plant cells because their cell wall and turgor pressure prevent the delivery, especially for larger molecules than the mesh size of the cell wall. This work is the first demonstration of the efficient photoinjection of megadalton molecules into a cytoplasm of an intact single plant cell by employing a femtosecond laser amplifier under moderate enzyme treatment conditions. The intense femtosecond laser pulse effectively formed a pore on the cell wall and membrane of Tobacco BY-2, and 2 MDa dextran molecules were introduced through the pore. Along with the pore formation, induced mechanical tensile stresses on BY-2 cells were considered to increase permeability of the cell membrane and enhance the uptake of large molecules. Moreover, the moderate enzyme treatment partially degraded the cell wall thereby facilitating the increase of the molecular introduction efficiency.
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Sane, O., Diouf, A., Morán Cruz, G., Savina, F., Méallet-Renault, R., Amigoni, S., Dieng, S. Y., Guittard, F., & Darmanin, T. (2019). Coral-like nanostructures. Materials Today, 31, 119–120.
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Tamura, M., Sekiguchi, T., Ishiuchi, S., Zehnacker-Rentien, A., & Fujii, M. (2019). Can the Partial Peptide SIVSF of the beta(2)-Adrenergic Receptor Recognize Chirality of the Epinephrine Neurotransmitter? Journal Of Physical Chemistry Letters, 10(10), 2470–2474.
Résumé: Chirality plays an essential role in biological molecular recognition, such as neurotransmission. Here, we applied electrospray-cold ion trap spectroscopy to complexes of a partial binding motif SIVSF of a beta(2)-adrenergic receptor pocket with L- and D-epinephrine AdH(+). The ultraviolet spectrum of the SIVSF-AdH(+) complex changed drastically when L-AdH(+) was replaced by its enantiomer. The isomer-selected infrared spectra revealed that D-AdH(+) was bound to SIVSF by its protonated amino-group or a single catechol OH and induced nonhelical secondary structures of SIVSF. This is in sharp contrast to the helical SIVSF complex with L-AdH(+), which is close to the natural binding structure with two catechol OHs binding in the receptor. This shows that a short pentapeptide SIVSF can distinguish the chirality of the ligand AdH(+) as well as the receptor. This stereoselectivity is suggested to arise from an additional interaction involving the hydroxyl group on the chiral carbon.
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Terzic, V., Pousse, G., Méallet-Renault, R., Grellier, P., & Dubois, J. (2019). Dibenzocyclooctynes: Effect of Aryl Substitution on Their Reactivity toward Strain-Promoted Alkyne–Azide Cycloaddition. The Journal of Organic Chemistry, 84(13), 8542–8551.
Résumé: Five new dibenzocyclooctynes bearing different substituents on their aryl moieties were synthesized and evaluated for their reactivity toward strain-promoted alkyne–azide cycloaddition (SPAAC). The dinaphthylcyclooctynes proved to be poorly reactive with azides, and the formation of triazole required many days compared to a few hours for the other cyclooctynes. Fluoride atoms and methoxy groups were also introduced to the aryl rings, leading to more active compounds. Oxidation of the alcohol on the cyclooctyne ring also increased the reaction rates by 3.5- to 6-fold. 3,9-Difluoro-4,8-dimethoxy-dibenzocyclooctyne-1-one thus displayed a SPAAC kinetic rate of 3.5 M–1 s–1, which is one of the highest rates ever described. Furthermore, the dibenzocyclooctyn-1-one displayed fluorescence properties that have allowed their detection in the protozoan parasites Plasmodium falciparum and Trypanosoma brucei by microscopy imaging, proving that they can cross cell membranes and that they are stable enough in biological media.
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Tiouitchi, G., Ali, M. A., Benyoussef, A., Hamedoun, M., Lachgar, A., Benaissa, M., Kara, A., Ennaoui, A., Mahmoud, A., Boschini, F., Oughaddou, H., El Kenz, A., & Mounkachi, O. (2019). An easy route to synthesize high-quality black phosphorus from amorphous red phosphorus. MATERIALS LETTERS, 236, 56–59.
Résumé: The development of an easy and efficient process for producing black phosphorus (BP) remains a bottleneck for the use of BP in large-scale applications. In this work, we present a simple, potentially scalable, and economically viable method for the preparation of high-quality BP from amorphous red phosphorus. BP was synthesized under low pressure and temperature conditions from red phosphorus via the addition of small quantities of copper, tin, and tin(IV) iodide. Characterization by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDX), high-resolution transmission electron microscopy (HR-TEM), and Raman spectroscopy were performed to confirm the high quality and purity of the formed BP.
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Tong, Y., Fuhr, J. D., Martiarena, M. L., Oughaddou, H., Enriquez, H., Nicolas, F., Chaouchi, K., Kubsky, S., & Bendounan, A. (2019). Properties of NTCDA Thin Films on Ag(110): Scanning Tunneling Microscopy, Photoemission, Near-Edge X-ray Fine Structure, and Density Functional Theory Investigations. JOURNAL OF PHYSICAL CHEMISTRY C, 123(1), 379–386.
Résumé: It is well proven that the properties of organic/metal interfaces play an utmost role in the performance of organic devices. Here we present a study on structural and electronic properties of high-quality 1,4,5,8-naphthalene tetracarboxylic dianhydride (NTCDA) films grown on an Ag(110) surface. High-resolution scanning tunneling microscopy and low-energy electron diffraction show the presence of two molecular domains. Density functional theory calculations indicate that the most stable location of NTCDA corresponds to anhydride oxygen attached to the Ag atoms along the [110] direction. Photoemission results of the C 1s and O 1s core levels demonstrate a strong interfacial bonding, inducing a charge transfer from the Ag metal to the molecular monolayer. An angular-dependent study of the C K-edge near-edge X-ray fine structure spectra provides detailed information concerning the evolution of the NTCDA orientation with the film thickness.
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Tran, T. - T., Pino, T., & Ha-Thi, M. - H. (2019). Watching Intermolecular Light-Induced Charge Accumulation on Naphthalene Diimide by Tris(bipyridyl)ruthenium(II) Photosensitizer. The Journal of Physical Chemistry C, 123(47), 28651–28658.
Résumé: Performing photocatalytic reactions to produce solar fuels requires the coupling of multiple photoinduced one-electron transfer steps on multielectronic catalysis. Understanding the light-driven charge accumulation in photocatalytic systems is of pivotal importance in the optimization process. Herein, we investigated the elementary steps of light-induced two-electron accumulation on a multicomponent system consisted of three archetypal molecules commonly used in photophysical studies, [Ru(bpy)3]2+, ascorbate as a reversible electron donor, and naphthalene diimide as a two-electron acceptor. Remarkably, accumulative charge separation was observed in both single-pulse and double-pulse experiments in a reversible manner, indicating a very high efficiency of charge transfer reactions. The doubly reduced state of ∼100 μs lifetime was obtained with a formation yield of 4.2%. Rate constants of all elementary steps in the formation and the relaxation of the doubly reduced state were determined with the aid of a newly developed numerical simulation method for this photosystem. To the best of our knowledge, this is the first investigation of charge accumulation with only a single-pulse excitation in a multicomponent system.
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Trimeche A., Battelier B., Becker D., Bertoldi A., Bouyer P., Braxmaier C., Charron E., Corgier R., Cornelius M., Douch K., Gaaloul N., Herrmann S., Müller J., Rasel E., Schubert C., Wu H., & Pereira dos Santos F. (2019). Concept study and preliminary design of a cold atom interferometer for space gravity gradiometry. Clas. Quant. Grav., 36, 215004.
Résumé: We study a space-based gravity gradiometer based on cold atom interferometry and its potential for the Earth's gravitational field mapping. The instrument architecture has been proposed in Carraz et al (2014 Microgravity Sci. Technol. 26 139) and enables high-sensitivity measurements of gravity gradients by using atom interferometers in a differential accelerometer configuration. We present the design of the instrument including its subsystems and analyze the mission scenario, for which we derive the expected instrument performances, the requirements on the sensor and its key subsystems, and the expected impact on the recovery of the Earth gravity field.
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Turbet, M., Tran, H., Pirali, O., Forget, F., Boulet, C., & Hartmann, J. - M. (2019). Far infrared measurements of absorptions by CH4 + CO2 and H2 + CO2 mixtures and implications for greenhouse warming on early Mars. Icarus, 321, 189–199.
Résumé: We present an experimental study of the absorption, between 40 and 640 cm−1, by CO2, CH4 and H2 gases as well as by H2 + CO2 and CH4 + CO2 mixtures at room temperature. A Fourier transform spectrometer associated to a multi-pass cell, whose optics were adjusted to obtain a 152 m path length, were used to record transmission spectra at total pressures up to about 0.98 bar. These measurements provide information concerning the collision-induced absorption (CIA) bands as well as about the wing of the CO2 15 µm band. Our results for the CIAs of pure gases are, within uncertainties, in agreement with previous determinations, validating our experimental and data analysis procedures. We then consider the CIAs by H2 + CO2 and CH4 + CO2 and the low frequency wing of the pure CO2 15 µm band, for which there are, to our knowledge, no previous measurements. We confirm experimentally the theoretical prediction of Wordsworth et al. (2017) that the H2 + CO2 and CH4 + CO2 CIAs are significantly stronger in the 50–550 cm−1 region than those of H2 + N2 and CH4 + N2, respectively. However, we find that the shape and the strength of these recorded CIAs differ from the aforementioned predictions. For the pure CO2 line-wings, we show that both the χ-factor deduced from measurements near 4 μm and a line-mixing model very well describe the observed strongly sub-Lorentzian behavior in the 500–600 cm−1 region. These experimental results open renewed perspectives for studies of the past climate of Mars and extrasolar analogues.
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Ueda, K., Sokell, E., Schippers, S., Aumayr, F., Sadeghpour, H., Burgdörfer, J., Lemell, C., Tong, X. - M., Pfeifer, T., Calegari, F., Palacios, A., Martin, F., Corkum, P., Sansone, G., Gryzlova, E. V., Grum-Grzhimailo, A. N., Piancastelli, M. N., Weber, P. M., Steinle, T., Amini, K., Biegert, J., Berrah, N., Kukk, E., Santra, R., Müller, A., Dowek, D., Lucchese, R. R., McCurdy, C. W., Bolognesi, P., Avaldi, L., Jahnke, T., Schöffler, M. S., Dörner, R., Mairesse, Y., Nahon, L., Smirnova, O., Schlathölter, T., Campbell, E. E. B., Rost, J. - M., Meyer, M., & Tanaka, K. A. (2019). Roadmap on photonic, electronic and atomic collision physics: I. Light–matter interaction. J. Phys. B: At. Mol. Opt. Phys., 52, 171001.
Résumé: We publish three Roadmaps on photonic, electronic and atomic collision physics in order to celebrate the 60th anniversary of the ICPEAC conference. In Roadmap I, we focus on the light–matter interaction. In this area, studies of ultrafast electronic and molecular dynamics have been rapidly growing, with the advent of new light sources such as attosecond lasers and x-ray free electron lasers. In parallel, experiments with established synchrotron radiation sources and femtosecond lasers using cutting-edge detection schemes are revealing new scientific insights that have never been exploited. Relevant theories are also being rapidly developed. Target samples for photon-impact experiments are expanding from atoms and small molecules to complex systems such as biomolecules, fullerene, clusters and solids. This Roadmap aims to look back along the road, explaining the development of these fields, and look forward, collecting contributions from twenty leading groups from the field.
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Xiao, Y., Shi, Y., Liu, P., Zhu, Y., Gao, L., Guo, Y., Chen, L., Chen, X., & Esaulov, V. A. (2019). Neutralization of keV-energy alkali-metal ions colliding at gold surfaces. NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS, 450, 73–76.
Résumé: Li+ and Na+ ions are scattered from Au(1 1 0) and Au(1 1 1) surfaces in the keV-energy range, respectively. The pronounced Li degrees and Na degrees fractions non-monotonically vary with incident energy and exit angle for high work function gold surfaces. In particular, the azimuthal angle dependence of Li degrees fraction has been observed at low incident energies for a grazing exit angle. The simple calculations are presented to compare with the experimental data. Our findings clearly indicate that both the perpendicular and parallel exit velocity affect the final neutral fraction.
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Yengui, M., Duverger, E., Sonnet, P., & Riedel, D. (2019). Translational Manipulation of Magnetic Cobalt Adatoms on the Si(100)-2 × 1 Surface at 9 K. J. Phys. Chem. C, 123(43), 26415–26423.
Résumé: The controlled motion of magnetic impurities on semiconductor (SC) surfaces is of crucial importance for atomic scale magnetic devices. Still challenging because of their strong reactivity with SCs, magnetic impurities are usually studied in bulk SCs, thus preventing their manipulation. Here, we show that a single Co adatom can be steadied on the bare Si(100)-2 × 1 surface in a pedestal configuration at low temperature, 9 K, and moved along the reconstructed silicon dimer rows via the use of a scanning tunneling microscope. The electronic characteristics of the Co adatom and its surroundings are investigated via topography and dI/dV measurements. Our findings reveal that the Si–Co bonding involves hybridization between the Si-p and the Co-pxpy orbitals. This configuration indicates that the Co-d orbitals remain weakly hybridized with the silicon atoms. These results are supported by density functional theory calculations where the role of the As dopant is discussed as well as the surface reconstruction. Therefore, we show that the motion direction of the Co adatom can be influenced by the surrounding c(4 × 2) or p(2 × 2) surface reconstruction phases, thus opening future interesting magnetic applications.
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Yuanzhi He, W. Z., Tao Guo, Guoqing Zhang, Wei Qin, Liu Zhang, Caifen Wang, Weifeng Zhu, Ming Yang, Xiaoxiao Hu, Vikramjeet Singh, Li Wu, Ruxandra Gref, Jiwen Zhang. (2019). Drug nanoclusters formed in confined nano-cages of CD-MOF: dramatic enhancement of solubility and bioavailability of azilsartan. Acta Pharm Sin B, 9(1), 97.
Résumé: Tremendous efforts have been devoted to the enhancement of drug solubility using nanotechnologies, but few of them are capable to produce drug particles with sizes less than a few nanometers. This challenge has been addressed here by using biocompatible versatile gamma-cyclodextrin (gamma-CD) metal-organic framework (CD-MOF) large molecular cages in which azilsartan (AZL) was successfully confined producing clusters in the nanometer range. This strategy allowed to improve the bioavailability of AZL in Sprague-Dawley rats by 9.7-fold after loading into CD-MOF. The apparent solubility of AZL/CD-MOF was enhanced by 340-fold when compared to the pure drug. Based on molecular modeling, a dual molecular mechanism of nanoclusterization and complexation of AZL inside the CD-MOF cages was proposed, which was confirmed by small angle X-ray scattering (SAXS) and synchrotron radiation-Fourier transform infrared spectroscopy (SR-FTIR) techniques. In a typical cage-like unit of CD-MOF, three molecules of AZL were included by the gamma-CD pairs, whilst other three AZL molecules formed a nanocluster inside the 1.7nm sized cavity surrounded by six gamma-CDs. This research demonstrates a dual molecular mechanism of complexation and nanoclusterization in CD-MOF leading to significant improvement in the bioavailability of insoluble drugs.
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Yuen, C. H., Lapierre, D., Gatti, F., Kokoouline, V., & Tyuterev, V. G. (2019). The Role of Ozone Vibrational Resonances in the Isotope Exchange Reaction (16)O(16)O + (18)O --> (18)O(16)O + (16)O: The Time-Dependent Picture. J Phys Chem A, 123(36), 7733–7743.
Résumé: We consider the time-dependent dynamics of the isotope exchange reaction in collisions between an oxygen molecule and an oxygen atom: (16)O(16)O + (18)O --> (16)O(18)O + (16)O. A theoretical approach using the multiconfiguration time-dependent Hartree method was employed to model the time evolution of the reaction. Two potential surfaces available in the literature were used in the calculations, and the results obtained with the two surfaces are compared with each other as well as with results of a previous theoretical time-independent approach. A good agreement for the reaction probabilities with the previous theoretical results is found. Comparing the results obtained using two potential energy surfaces allows us to understand the role of the reef/shoulder-like feature in the minimum energy path of the reaction in the isotope exchange process. Also, it was found that the distribution of final products of the reaction is highly anisotropic, which agrees with experimental observations and, at the same time, suggests that the family of approximated statistical approaches, assuming a randomized distribution over final exit channels, is not applicable to this case.
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Zhang, Z., Zhang Z, Gatti, F., Gatti F, Zhang, D. H., & Zhang DH. (2019). Full dimensional quantum mechanical calculations of the reaction probability of the H + NH3 collision based on a mixed Jacobi and Radau description. J Chem Phys, 150(20), 204301.
Résumé: The collision between hydrogen and ammonia is a benchmark system to study chemical elementary reactions with five atoms. In this work, we present a description of the system based on mixed Jacobi and Radau coordinates combined with the time-dependent wave packet method to study the H + NH3 reaction. The Radau coordinates are used to describe the reactive moiety NH2. A salient feature of this approach is that the present coordinates have a great advantage that a very small number of basis set functions can be used to describe the NH2 group. Potential-optimized discrete variable representation basis is applied for the vibrational coordinates of the reagent NH3. The reaction probabilities for several initial vibrational states are presented in this paper. The role of the different vibrational excitations on the reactivity is thoroughly described.
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Actes de Conférences |
Kennedy, E. T., Mosnier, J. P., Van Kampen, P., Bizau, J. - M., Cubaynes, D., Guilbaud, S., Carniato, S., Puglisi, A., & Sisourat, N. (2019). Vibrational effects in the photo-ion yield spectrum of the SiH<sub>2</sub><sup>+</sup>molecular ion following 2p inner-shell excitation. In Journal of Physics: Conference Series (Vol. 1289, 012003).
Résumé: We report on complementary theoretical and laboratory investigations of the 2p ion yield cross sections for the molecular-ion series SiHn+ (n = 1, 2, 3), in the 95-108 eV photon energy range, below the L-shell threshold. The experiments used an electron cyclotron resonance (ECR) plasma molecular-ion source coupled with monochromatised synchrotron radiation in a merged-beam configuration. The experimental spectra are compared with total photoabsorption cross-sectional profiles calculated using an ab initio configuration interaction method inclusive of spin-orbit coupling and the vibrational dynamics. The experimental results show vibrationally resolved resonances for SiH2+ in the 98-102 eV range. The calculations indicate twenty four core-excited states below the energy of 102 eV, of which only four contribute significantly to the observed spectrum. These states correspond to the excitation of an atomic-like 2p electron to the SiH2+ (5a1) valence orbital.
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Chapitres de Livres |
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Pérez-Mellor A. Zehnacker A. (2019). Chirality Effects in Jet-Cooled Cyclic Dipeptides. In Ebata T. Fujii M. (Ed.), Physical Chemistry of Cold Gas-Phase Functional Molecules and Clusters (pp. 63–87). Singapore: Springer.
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Jain-Beuguel C, Li, X., Houel-Renault, L., Modjinou T, Gref R, Renard, E., & Langlois V. (2019). Water-Soluble Poly(3-hydroxyalkanoate) Sulfonate: Versatile Biomaterials Used as Coatings for Highly Porous Nano-Metal Organic Framework. (Vol. 20).
Résumé: Water-soluble poly(3-hydroxyalkanoate) containing ionic groups were designed by two successive photoactivated thiol-ene reactions. Sodium-3-mercapto-1-ethanesulfonate (SO3(-)) and poly(ethylene glycol) (PEG) methyl ether thiol were grafted onto poly(3-hydroxyoctanoate-co-3-hydroxyundecenoate) PHO(67)U(33) to introduce both ionic groups and hydrophilic moieties. The grafted copolymers PHO(67)SO3(-)(20)PEG(13) were then used as biocompatible coatings of nano-metal organic frameworks (nanoMOFs) surfaces. Scanning electron microscopy and scanning transmission electron microscopy coupled with energy dispersive X-ray characterizations have clearly demonstrated the presence of the copolymer on the MOF surface. These coated nanoMOFs are stable in aqueous and physiological fluids. Cell proliferation and cytotoxicity tests performed on murine macrophages J774.A1 revealed no cytotoxic side effect. Thus, biocompatibility and stability of these novel hybrid porous MOF structures encourage their use in the development of effective therapeutic nanoparticles.
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Jain-Beuguel, C., Li, X., Houel-Renault, L., Modjinou, T., Simon-Colin, C., Gref, R., Renard E, & Langlois V. (2019). Water-Soluble Poly(3-hydroxyalkanoate) Sulfonate: Versatile Biomaterials Used as Coatings for Highly Porous Nano-Metal Organic Framework. (Vol. 20).
Résumé: Water-soluble poly(3-hydroxyalkanoate) containing ionic groups were designed by two successive photoactivated thiol-ene reactions. Sodium-3-mercapto-1-ethanesulfonate (SO3(-)) and poly(ethylene glycol) (PEG) methyl ether thiol were grafted onto poly(3-hydroxyoctanoate-co-3-hydroxyundecenoate) PHO(67)U(33) to introduce both ionic groups and hydrophilic moieties. The grafted copolymers PHO(67)SO3(-)(20)PEG(13) were then used as biocompatible coatings of nano-metal organic frameworks (nanoMOFs) surfaces. Scanning electron microscopy and scanning transmission electron microscopy coupled with energy dispersive X-ray characterizations have clearly demonstrated the presence of the copolymer on the MOF surface. These coated nanoMOFs are stable in aqueous and physiological fluids. Cell proliferation and cytotoxicity tests performed on murine macrophages J774.A1 revealed no cytotoxic side effect. Thus, biocompatibility and stability of these novel hybrid porous MOF structures encourage their use in the development of effective therapeutic nanoparticles.
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Pastor A,, Machelart A,, Li X,, Willand N,., Baulard A, Brodin, P., Gref R, & Desmaele D. (2019). A novel codrug made of the combination of ethionamide and its potentiating booster: synthesis, self-assembly into nanoparticles and antimycobacterial evaluation. (Vol. 17).
Résumé: Ethionamide (ETH) is one of the most widely used second-line chemotherapeutic drugs for the treatment of multi-drug-resistant tuberculosis. The bioactivation and activity of ETH is dramatically potentiated by a family of molecules called “boosters” among which BDM43266 is one of the most potent. However, the co-administration of these active molecules is hampered by their low solubility in biological media and by the strong tendency of ETH to crystallize. A novel strategy that involves synthesizing a codrug able to self-associate into nanoparticles prone to be taken up by infected macrophages is proposed here. This codrug is designed by tethering N-hydroxymethyl derivatives of both ETH and its booster through a glutaric linker. This codrug self-assembles into nanoparticles of around 200 nm, stable upon extreme dilution without disaggregating as well as upon concentration. The nanoparticles of the codrug can be intranasally administered overcoming the unfavorable physico-chemical profiles of the parent drugs. Intrapulmonary delivery of the codrug nanoparticles to Mtb infected mice via the intranasal route at days 7, 9, 11, 14, 16 and 18 post-infection reduces the bacterial load in the lungs by a factor of 6.
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Shailendra Shakya, Y. H., Xiaohong Ren, Tao Guo, Abi Maharjan, Ting Luo, Tingting Wang, Ramesh Dhakhwa, Balmukunda Regmi, Haiyan Li, Ruxandra Gref, Jiwen Zhang. (2019). Ultrafine Silver Nanoparticles Embedded in Cyclodextrin Metal-Organic Frameworks with GRGDS Functionalization to Promote Antibacterial and Wound Healing Application. (Vol. 15).
Résumé: The challenge of bacterial infection increases the risk of mortality and morbidity in acute and chronic wound healing. Silver nanoparticles (Ag NPs) are a promising new version of conventional antibacterial nanosystem to fight against the bacterial resistance in concern of the drug discovery void. However, there are several challenges in controlling the size and colloidal stability of Ag NPs, which readily aggregate or coalesce in both solid and aqueous state. In this study, a template-guided synthesis of ultrafine Ag NPs of around 2 nm using water-soluble and biocompatible gamma-cyclodextrin metal-organic frameworks (CD-MOFs) is reported. The CD-MOF based synthetic strategy integrates AgNO3 reduction and Ag NPs immobilization in one pot achieving dual functions of reduced particle size and enhanced stability. Meanwhile, the synthesized Ag NPs are easily dispersible in aqueous media and exhibit effective bacterial inhibition. The surface modification of cross-linked CD-MOF particles with GRGDS peptide boosts the hemostatic effect that further enhances wound healing in synergy with the antibacterial effect. Hence, the strategy of ultrafine Ag NPs synthesis and immobilization in CD-MOFs together with GRGDS modification holds promising potential for the rational design of effective wound healing devices.
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