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1. Gaia Data Release 3: Chemical cartography of the Milky Way

Author: Collaboration, Gaia, Recio-Blanco, A., Kordopatis, G., de Laverny, P., Palicio, P. A., Spagna, A., Spina, L., Katz, D., Re Fiorentin, P., Poggio, E., Mcmillan, P. J., Vallenari, A., Lattanzi, M. G., Seabroke, G. M., Casamiquela, L., Bragaglia, A., Antoja, T., Bailer-Jones, C. A. L., Andrae, R., Fouesneau, M., Cropper, M., Cantat-Gaudin, T., Heiter, U., Bijaoui, A., Brown, A. G. A., Prusti, T., de Bruijne, J. H. J., Arenou, F., Babusiaux, C., Biermann, M., Creevey, O. L., Ducourant, C., Evans, D. W., Eyer, L., Guerra, R., Hutton, A., Jordi, C., Klioner, S. A., Lammers, U. L., Lindegren, L., Luri, X., Mignard, F., Panem, C., Pourbaix, D., Randich, S., Sartoretti, P., Soubiran, C., Tanga, P., Walton, N. A., Bastian, U., Drimmel, R., Jansen, F., van Leeuwen, F., Bakker, J., Cacciari, C., Castañeda, J., De Angeli, F., Fabricius, C., Frémat, Y., Galluccio, L., Guerrier, A., Masana, E., Messineo, R., Mowlavi, N., Nicolas, C., Nienartowicz, K., Pailler, F., Panuzzo, P., Riclet, F., Roux, W., Sordo, R., Thévenin, F., Gracia-Abril, G., Portell, J., Teyssier, D., Altmann, M., Audard, M., Bellas-Velidis, I., Benson, K., Berthier, J., Blomme, R., Burgess, P. W., Busonero, D., Busso, G., Cánovas, H., Carry, B., Cellino, A., Cheek, N., Clementini, G., Damerdji, Y., Davidson, M., de Teodoro, P., Nuñez Campos, M., Delchambre, L., Dell'Oro, A., Esquej, P., Fernández-Hernández, J., Fraile, E., Garabato, D., García-Lario, P., Gosset, E., Haigron, R., Halbwachs, J. -L., Hambly, N. C., Harrison, D. L., Hernández, J., Hestroffer, D., Hodgkin, S. T., Holl, B., Janßen, K., Jevardat de Fombelle, G., Jordan, S., Krone-Martins, A., Lanzafame, A. C., Löffler, W., Marchal, O., Marrese, P. M., Moitinho, A., Muinonen, K., Osborne, P., Pancino, E., Pauwels, T., Reylé, C., Riello, M., Rimoldini, L., Roegiers, T., Rybizki, J., Sarro, L. M., Siopis, C., Smith, M., Sozzetti, A., Utrilla, E., van Leeuwen, M., Abbas, U., Ábrahám, P., Abreu Aramburu, A., Aerts, C., Aguado, J. J., Ajaj, M., Aldea-Montero, F., Altavilla, G., Álvarez, M. A., Alves, J., Anders, F., Anderson, R. I., Anglada Varela, E., Baines, D., Baker, S. G., Balaguer-Núñez, L., Balbinot, E., Balog, Z., Barache, C., Barbato, D., Barros, M., Barstow, M. A., Bartolomé, S., Bassilana, J. -L., Bauchet, N., Becciani, U., Bellazzini, M., Berihuete, A., Bernet, M., Bertone, S., Bianchi, L., Binnenfeld, A., Blanco-Cuaresma, S., Boch, T., Bombrun, A., Bossini, D., Bouquillon, S., Bramante, L., Breedt, E., Bressan, A., Brouillet, N., Brugaletta, E., Bucciarelli, B., Burlacu, A., Butkevich, A. G., Buzzi, R., Caffau, E., Cancelliere, R., Carballo, R., Carlucci, T., Carnerero, M. I., Carrasco, J. M., Castellani, M., Castro-Ginard, A., Chaoul, L., Charlot, P., Chemin, L., Chiaramida, V., Chiavassa, A., Chornay, N., Comoretto, G., Contursi, G., Cooper, W. J., Cornez, T., Cowell, S., Crifo, F., Crosta, M., Crowley, C., Dafonte, C., Dapergolas, A., David, P., De Luise, F., De March, R., De Ridder, J., de Souza, R., de Torres, A., del Peloso, E. F., del Pozo, E., Delbo, M., Delgado, A., Delisle, J. -B., Demouchy, C., Dharmawardena, T. E., Di Matteo, P., Diakite, S., Diener, C., Distefano, E., Dolding, C., Edvardsson, B., Enke, H., Fabre, C., Fabrizio, M., Faigler, S., Fedorets, G., Fernique, P., Figueras, F., Fournier, Y., Fouron, C., Fragkoudi, F., Gai, M., Garcia-Gutierrez, A., Garcia-Reinaldos, M., García-Torres, M., Garofalo, A., Gavel, A., Gavras, P., Gerlach, E., Geyer, R., Giacobbe, P., Gilmore, G., Girona, S., Giuffrida, G., Gomel, R., Gomez, A., González-Núñez, J., González-Santamaría, I., González-Vidal, J. J., Granvik, M., Guillout, P., Guiraud, J., Gutiérrez-Sánchez, R., Guy, L. P., Hatzidimitriou, D., Hauser, M., Haywood, M., Helmer, A., Helmi, A., Sarmiento, M. H., Hidalgo, S. L., Hładczuk, N., Hobbs, D., Holland, G., Huckle, H. E., Jardine, K., Jasniewicz, G., Jean-Antoine Piccolo, A., Jiménez-Arranz, Ó., Juaristi Campillo, J., Julbe, F., Karbevska, L., Kervella, P., Khanna, S., Korn, A. J., Kóspál, Á, Kostrzewa-Rutkowska, Z., Kruszyńska, K., Kun, M., Laizeau, P., Lambert, S., Lanza, A. F., Lasne, Y., Le Campion, J. -F., Lebreton, Y., Lebzelter, T., Leccia, S., Leclerc, N., Lecoeur-Taibi, I., Liao, S., Licata, E. L., Lindstrøm, H. E. P., Lister, T. A., Livanou, E., Lobel, A., Lorca, A., Loup, C., Madrero Pardo, P., Magdaleno Romeo, A., Managau, S., Mann, R. G., Manteiga, M., Marchant, J. M., Marconi, M., Marcos, J., Marcos Santos, M. M. S., Marín Pina, D., Marinoni, S., Marocco, F., Marshall, D. J., Polo, L. Martin, Martín-Fleitas, J. M., Marton, G., Mary, N., Masip, A., Massari, D., Mastrobuono-Battisti, A., Mazeh, T., Messina, S., Michalik, D., Millar, N. R., Mints, A., Molina, D., Molinaro, R., Molnár, L., Monari, G., Monguió, M., Montegriffo, P., Montero, A., Mor, R., Mora, A., Morbidelli, R., Morel, T., Morris, D., Muraveva, T., Murphy, C. P., Musella, I., Nagy, Z., Noval, L., Ocaña, F., Ogden, A., Ordenovic, C., Osinde, J. O., Pagani, C., Pagano, I., Palaversa, L., Pallas-Quintela, L., Panahi, A., Payne-Wardenaar, S., Peñalosa Esteller, X., Penttilä, A., Pichon, B., Piersimoni, A. M., Pineau, F. -X., Plachy, E., Plum, G., Prša, A., Pulone, L., Racero, E., Ragaini, S., Rainer, M., Raiteri, C. M., Ramos, P., Ramos-Lerate, M., Regibo, S., Richards, P. J., Rios Diaz, C., Ripepi, V., Riva, A., Rix, H. -W., Rixon, G., Robichon, N., Robin, A. C., Robin, C., Roelens, M., Rogues, H. R. O., Rohrbasser, L., Romero-Gómez, M., Rowell, N., Royer, F., Ruz Mieres, D., Rybicki, K. A., Sadowski, G., Sáez Núñez, A., Sagristà Sellés, A., Sahlmann, J., Salguero, E., Samaras, N., Sanchez Gimenez, V., Sanna, N., Santoveña, R., Sarasso, M., Schultheis, M., Sciacca, E., Segol, M., Segovia, J. C., Ségransan, D., Semeux, D., Shahaf, S., Siddiqui, H. I., Siebert, A., Siltala, L., Silvelo, A., Slezak, E., Slezak, I., Smart, R. L., Snaith, O. N., Solano, E., Solitro, F., Souami, D., Souchay, J., Spoto, F., Steele, I. A., Steidelmüller, H., Stephenson, C. A., Süveges, M., Surdej, J., Szabados, L., Szegedi-Elek, E., Taris, F., Taylor, M. B., Teixeira, R., Tolomei, L., Tonello, N., Torra, F., Torra, J., Torralba Elipe, G., Trabucchi, M., Tsounis, A. T., Turon, C., Ulla, A., Unger, N., Vaillant, M. V., van Dillen, E., van Reeven, W., Vanel, O., Vecchiato, A., Viala, Y., Vicente, D., Voutsinas, S., Weiler, M., Wevers, T., Wyrzykowski, Ł., Yoldas, A., Yvard, P., Zhao, H., Zorec, J., Zucker, S., Zwitter, T., Joseph Louis LAGRANGE (LAGRANGE), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), Observatoire de la Côte d'Azur (OCA), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Monash University [Clayton], Galaxies, Etoiles, Physique, Instrumentation (GEPI), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry [UCL, London], University College of London [London] (UCL), INAF - Osservatorio Astronomico di Padova (OAPD), Istituto Nazionale di Astrofisica (INAF), Mullard Space Science Laboratory (MSSL), Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Alma Mater Studiorum Università di Bologna [Bologna] (UNIBO), Institut de Ciencies del Cosmos (ICCUB), Universitat de Barcelona (UB), Max Planck Institute for Astronomy (MPIA), Max-Planck Institute for Astronomy, Konigstuhl 17, D-69117, Heidelberg, Germany, Laboratoire d'études spatiales et d'instrumentation en astrophysique = Laboratory of Space Studies and Instrumentation in Astrophysics (LESIA), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut de Physique de Rennes (IPR), and Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Astrophysics and Astronomy, Cosmology and Nongalactic Astrophysics (astro-ph.CO), astro-ph.SR, Astronomy, astro-ph.GA, Galaxy: abundances Stars: abundances Galaxy: evolution Galaxy: kinematics and dynamics open clusters and associations Galaxy:structure Galaxy: disc Galaxy: halo, open clusters and associations, Galaxy: disc, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, evolution [Galaxy], halo [Galaxy], Astrophysics::Solar and Stellar Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Earth and Planetary Astrophysics (astro-ph.EP), High Energy Astrophysical Phenomena (astro-ph.HE), astro-ph.HE, Galaxy: evolution, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Stars: abundances, abundances [Galaxy], Astronomy and Astrophysics, kinematics and dynamics [Galaxy], Astrophysics - Astrophysics of Galaxies, Galaxy: halo, abundances [stars], Galaxy:structure, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), astro-ph.EP, astro-ph.CO, Galaxy: abundances, Astrophysics::Earth and Planetary Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, disk [Galaxy], Galaxy: kinematics and dynamics, astro-ph.IM, Astrophysics - Cosmology and Nongalactic Astrophysics, Astrophysics - Earth and Planetary Astrophysics
Abstract: Gaia DR3 opens a new era of all-sky spectral analysis of stellar populations thanks to the nearly 5.6 million stars observed by the RVS and parametrised by the GSP-spec module. The all-sky Gaia chemical cartography allows a powerful and precise chemo-dynamical view of the Milky Way with unprecedented spatial coverage and statistical robustness. First, it reveals the strong vertical symmetry of the Galaxy and the flared structure of the disc. Second, the observed kinematic disturbances of the disc -- seen as phase space correlations -- and kinematic or orbital substructures are associated with chemical patterns that favour stars with enhanced metallicities and lower [alpha/Fe] abundance ratios compared to the median values in the radial distributions. This is detected both for young objects that trace the spiral arms and older populations. Several alpha, iron-peak elements and at least one heavy element trace the thin and thick disc properties in the solar cylinder. Third, young disc stars show a recent chemical impoverishment in several elements. Fourth, the largest chemo-dynamical sample of open clusters analysed so far shows a steepening of the radial metallicity gradient with age, which is also observed in the young field population. Finally, the Gaia chemical data have the required coverage and precision to unveil galaxy accretion debris and heated disc stars on halo orbits through their [alpha/Fe] ratio, and to allow the study of the chemo-dynamical properties of globular clusters. Gaia DR3 chemo-dynamical diagnostics open new horizons before the era of ground-based wide-field spectroscopic surveys. They unveil a complex Milky Way that is the outcome of an eventful evolution, shaping it to the present day (abridged)., Astronomy and Astrophysics (accepted, in press)
Published: 2022
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2. Ensembles are required to handle aleatoric and parametric uncertainty in molecular dynamics simulation

Author: Peter V. Coveney, Maxime Vassaux, Shunzhou Wan, Wouter Edeling, Laboratoire de Mécanique et Technologie (LMT), École normale supérieure - Cachan (ENS Cachan)-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry [UCL, London], University College of London [London] (UCL), Institut de Physique de Rennes (IPR), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), and Centrum Wiskunde & Informatica (CWI)
Subjects: Random seed, Ensemble averaging, [INFO.INFO-CG]Computer Science [cs]/Computational Geometry [cs.CG], 01 natural sciences, Article, [SPI.MAT]Engineering Sciences [physics]/Materials, [PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], 03 medical and health sciences, [PHYS.MECA.STRU]Physics [physics]/Mechanics [physics]/Structural mechanics [physics.class-ph], [PHYS.MECA.SOLID]Physics [physics]/Mechanics [physics]/Solid mechanics [physics.class-ph], 0103 physical sciences, [SPI.GCIV.RISQ]Engineering Sciences [physics]/Civil Engineering/Risques, [MATH.MATH-AP]Mathematics [math]/Analysis of PDEs [math.AP], Statistical physics, Sensitivity (control systems), Physical and Theoretical Chemistry, Uncertainty quantification, ComputingMilieux_MISCELLANEOUS, 030304 developmental biology, Parametric statistics, Physics, 0303 health sciences, 010304 chemical physics, [SPI.GCIV.GEOTECH]Engineering Sciences [physics]/Civil Engineering/Géotechnique, Variance (accounting), [PHYS.MECA.MSMECA]Physics [physics]/Mechanics [physics]/Materials and structures in mechanics [physics.class-ph], [INFO.INFO-NA]Computer Science [cs]/Numerical Analysis [cs.NA], 3. Good health, Computer Science Applications, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, [SPI.GCIV.STRUCT]Engineering Sciences [physics]/Civil Engineering/Structures, [SPI.GCIV.MAT]Engineering Sciences [physics]/Civil Engineering/Matériaux composites et construction, [SPI.GCIV.GCN]Engineering Sciences [physics]/Civil Engineering/Génie civil nucléaire, Random variable, Energy (signal processing)
Abstract: Classical molecular dynamics is a computer simulation technique that is in widespread use across many areas of science, from physics and chemistry to materials, biology, and medicine. The method continues to attract criticism due its oft-reported lack of reproducibility which is in part due to a failure to submit it to reliable uncertainty quantification (UQ). Here we show that the uncertainty arises from a combination of (i) the input parameters and (ii) the intrinsic stochasticity of the method controlled by the random seeds. To illustrate the situation, we make a systematic UQ analysis of a widely used molecular dynamics code (NAMD), applied to estimate binding free energy of a ligand-bound to a protein. In particular, we replace the usually fixed input parameters with random variables, systematically distributed about their mean values, and study the resulting distribution of the simulation output. We also perform a sensitivity analysis, which reveals that, out of a total of 175 parameters, just six dominate the variance in the code output. Furthermore, we show that binding energy calculations dampen the input uncertainty, in the sense that the variation around the mean output free energy is less than the variation around the mean of the assumed input distributions, if the output is ensemble-averaged over the random seeds. Without such ensemble averaging, the predicted free energy is five times more uncertain. The distribution of the predicted properties is thus strongly dependent upon the random seed. Owing to this substantial uncertainty, robust statistical measures of uncertainty in molecular dynamics simulation require the use of ensembles in all contexts.
Published: 2021
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3. VECMAtk: a scalable verification, validation and uncertainty quantification toolkit for scientific simulations

Author: Linda van Veen, O. O. Luk, Peter V. Coveney, Robert C. Sinclair, Jalal Lakhlili, Maxime Vassaux, Tomasz Piontek, D. P. Coster, Paul Karlshoefer, David W. Wright, N. Monnier, Diana Suleimenova, Erwan Raffin, Piotr Kopta, Michal Kulczewski, Daan Crommelin, Robin A. Richardson, Fredrik Jansson, Mariusz Bieniek, Derek Groen, Hamid Arabnejad, Anna Nikishova, Vytautas Jancauskas, O. Hoenen, Bartosz Bosak, Wouter Edeling, Brunel University London [Uxbridge], Centrum Wiskunde & Informatica, Amsterdam (CWI), Department of Chemistry [UCL, London], University College of London [London] (UCL), Computational Science Lab (IVI, FNWI), Analysis (KDV, FNWI), KdV Other Research (FNWI), Faculty of Science, and Centrum Wiskunde & Informatica, Amsterdam (CWI), The Netherlands
Subjects: FOS: Computer and information sciences, 010504 meteorology & atmospheric sciences, uncertainty quantification, General Mathematics, General Physics and Astronomy, [INFO.INFO-CG]Computer Science [cs]/Computational Geometry [cs.CG], 01 natural sciences, 010305 fluids & plasmas, [SPI.MAT]Engineering Sciences [physics]/Materials, [PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], multiscale simulations, Software, [PHYS.MECA.STRU]Physics [physics]/Mechanics [physics]/Structural mechanics [physics.class-ph], 0103 physical sciences, Validation, [PHYS.MECA.SOLID]Physics [physics]/Mechanics [physics]/Solid mechanics [physics.class-ph], [SPI.GCIV.RISQ]Engineering Sciences [physics]/Civil Engineering/Risques, [MATH.MATH-AP]Mathematics [math]/Analysis of PDEs [math.AP], Sensitivity (control systems), Uncertainty quantification, Reliability (statistics), Research Articles, 0105 earth and related environmental sciences, validation, business.industry, [SPI.GCIV.GEOTECH]Engineering Sciences [physics]/Civil Engineering/Géotechnique, General Engineering, Verification, Articles, [PHYS.MECA.MSMECA]Physics [physics]/Mechanics [physics]/Materials and structures in mechanics [physics.class-ph], [INFO.INFO-NA]Computer Science [cs]/Numerical Analysis [cs.NA], cs.MS, Range (mathematics), Scalability, Key (cryptography), Computer Science - Mathematical Software, [SPI.GCIV.STRUCT]Engineering Sciences [physics]/Civil Engineering/Structures, Multiscale simulations, [SPI.GCIV.MAT]Engineering Sciences [physics]/Civil Engineering/Matériaux composites et construction, verification, Software engineering, business, Focus (optics), Mathematical Software (cs.MS), [SPI.GCIV.GCN]Engineering Sciences [physics]/Civil Engineering/Génie civil nucléaire
Abstract: We present the VECMA toolkit (VECMAtk), a flexible software environment for single and multiscale simulations that introduces directly applicable and reusable procedures for verification, validation (V&V), sensitivity analysis (SA) and uncertainty quantification (UQ). It enables users to verify key aspects of their applications, systematically compare and validate the simulation outputs against observational or benchmark data, and run simulations conveniently on any platform from the desktop to current multi-petascale computers. In this sequel to our paper on VECMAtk which we presented last year, we focus on a range of functional and performance improvements that we have introduced, cover newly introduced components, and applications examples from seven different domains such as conflict modelling and environmental sciences. We also present several implemented patterns for UQ/SA and V&V, and guide the reader through one example concerning COVID-19 modelling in detail., 23 pages, 10 figures
Published: 2021
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4. Photoemission core level binding energies from multiple sized nanoparticles on the same support:TiO2(110)/Au

Author: Chi L. Pang, Chi Ming Yim, Geoff Thornton, Francesco Maccherozzi, Sarnjeet S. Dhesi, Andrew Mellor, Christopher A. Muryn, Hicham Idriss, Axel Wilson, Department of Chemistry [UCL, London], University College of London [London] (UCL), and DIAMOND Light source
Subjects: Materials science, Microscope, 010304 chemical physics, Photoemission spectroscopy, Binding energy, Analytical chemistry, General Physics and Astronomy, Nanoparticle, Substrate (electronics), Physics and Astronomy(all), 010402 general chemistry, 01 natural sciences, 0104 chemical sciences, law.invention, Electron transfer, law, 0103 physical sciences, Monolayer, Scanning tunneling microscope, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], Physical and Theoretical Chemistry, ComputingMilieux_MISCELLANEOUS
Abstract: A novel method of measuring the core level binding energies of multiple sized nanoparticles on the same substrate is demonstrated using the early stage of Au nanoparticle growth on reduced r-TiO2(110). This method employed in situ scanning tunneling microscopy (STM) and microfocused X-ray photoemission spectroscopy. An STM tip-shadowing method was used to synthesize patterned areas of Au nanoparticles on the substrate with different coverages and sizes. Patterns were identified and imaged using a UV photoelectron emission microscope. The Au 4f core level binding energies of the nanoparticles were investigated as a function of Au nanoparticle coverage and size. A combination of initial and final state effects modifies the binding energies of the Au 4f core levels as the nanoparticle size changes. When single Au atoms and Au3 clusters are present, the Au 4f7/2 binding energy, 84.42 eV, is similar to that observed at a high coverage (1.8 monolayer equivalent), resulting from a cancellation of initial and final state effects. As the coverage is increased, there is a decrease in binding energy, which then increases at a higher coverage to 84.39 eV. These results are consistent with a Volmer-Weber nucleation-growth model of Au nanoparticles at oxygen vacancies, resulting in electron transfer to the nanoparticles.
Published: 2020
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5. Combination of theoretical and in-situ experimental investigations of the role of lithium dopant in manganese nitride: a two-stage reagent for ammonia synthesis

Author: Nicholas Bion, Constantinos D. Zeinalipour-Yazdi, Justin S. J. Hargreaves, Richard Charles Arthur Catlow, Said Laassiri, Unité de Catalyse et Chimie du Solide - UMR 8181 (UCCS), Université d'Artois (UA)-Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), WestCHEM, School of Chemistry, University of Glasgow-University of Glasgow, School of Sciences, University of Greenwich, Institut de Chimie des Milieux et Matériaux de Poitiers (IC2MP), Université de Poitiers-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry [UCL, London], University College of London [London] (UCL), and Centrale Lille Institut (CLIL)-Université d'Artois (UA)-Centrale Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Lille
Subjects: Materials science, Dopant, Inorganic chemistry, chemistry.chemical_element, 02 engineering and technology, Manganese, [CHIM.CATA]Chemical Sciences/Catalysis, Nitride, 010402 general chemistry, 021001 nanoscience & nanotechnology, Q1, 01 natural sciences, Nitrogen, 0104 chemical sciences, Ammonia production, Ammonia, chemistry.chemical_compound, chemistry, Reagent, [CHIM]Chemical Sciences, Lithium, Physical and Theoretical Chemistry, 0210 nano-technology
Abstract: Manganese nitride related materials are of interest as two-stage reagents for ammonia synthesis via nitrogen chemical looping. However, unless they are doped with a co-cation, manganese nitrides are thermochemically stable and a high temperature is required to produce ammonia under reducing conditions, thereby hindering their use as nitrogen transfer materials. Nevertheless, when lithium is used as dopant, ammonia generation can be observed at a reaction temperature as low as 300 °C. In order to develop strategies for the improvement of the reactivity of nitride materials in the context of two-stage reagents, it is necessary to understand the intrinsic role of the dopant in the mechanism of ammonia synthesis. To this end, we have investigated the role of lithium in increasing the manganese nitride reactivity by in situ neutron diffraction studies and N2 and H2 isotopic exchange reactions supplemented by DFT calculations.
Published: 2020
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6. Towards heterogeneous multi-scale computing on large scale parallel supercomputers

Author: Maxime Vassaux, Saad Alowayyed, Alfons G. Hoekstra, Peter V. Coveney, Benjamin Czaja, Computational Science Lab (IVI, FNWI), Laboratoire de Mécanique et Technologie (LMT), École normale supérieure - Cachan (ENS Cachan)-Centre National de la Recherche Scientifique (CNRS), King Abdulaziz City for Science and Technology [Riyadh], Department of Chemistry [UCL, London], University College of London [London] (UCL), Computational Science Lab [Amsterdam], and University of Amsterdam [Amsterdam] (UvA)
Subjects: Exploit, Computer Networks and Communications, Computer science, Distributed computing, [INFO.INFO-CG]Computer Science [cs]/Computational Geometry [cs.CG], 01 natural sciences, 010305 fluids & plasmas, Scheduling (computing), [SPI.MAT]Engineering Sciences [physics]/Materials, [PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], Surrogate model, [PHYS.MECA.STRU]Physics [physics]/Mechanics [physics]/Structural mechanics [physics.class-ph], 0103 physical sciences, [PHYS.MECA.SOLID]Physics [physics]/Mechanics [physics]/Solid mechanics [physics.class-ph], [SPI.GCIV.RISQ]Engineering Sciences [physics]/Civil Engineering/Risques, [MATH.MATH-AP]Mathematics [math]/Analysis of PDEs [math.AP], surrogate model, 010306 general physics, multi-scale modelling, ComputingMilieux_MISCELLANEOUS, Queueing theory, [SPI.GCIV.GEOTECH]Engineering Sciences [physics]/Civil Engineering/Géotechnique, computational science, Load balancing (computing), [PHYS.MECA.MSMECA]Physics [physics]/Mechanics [physics]/Materials and structures in mechanics [physics.class-ph], [INFO.INFO-NA]Computer Science [cs]/Numerical Analysis [cs.NA], [INFO.INFO-MO]Computer Science [cs]/Modeling and Simulation, Exascale computing, Computer Science Applications, high performance computing, Computational Theory and Mathematics, Hardware and Architecture, A priori and a posteriori, Pilot job, exascale, [SPI.GCIV.STRUCT]Engineering Sciences [physics]/Civil Engineering/Structures, [INFO.INFO-BI]Computer Science [cs]/Bioinformatics [q-bio.QM], [INFO.INFO-DC]Computer Science [cs]/Distributed, Parallel, and Cluster Computing [cs.DC], [SPI.GCIV.MAT]Engineering Sciences [physics]/Civil Engineering/Matériaux composites et construction, [SPI.GCIV.GCN]Engineering Sciences [physics]/Civil Engineering/Génie civil nucléaire, Software, heterogeneous multiscale computing, Information Systems
Abstract: International audience; New applications exploiting emerging exascale computing resources efficiently, while providing meaningful scientific results, are lagging behind. Multi-scale models, especially multi-scale applications, can potentially run on the exascale. We have established that a class of multi-scale applications implementing the heterogeneous multi-scale model follows, a heterogeneous multi-scale computing (HMC) pattern, which typically features a macroscopic model synchronising numerous independent microscopic model simulations. Consequently, communication between microscopic simulations is limited. Furthermore, a surrogate model can often be introduced between macroscale and micro-scale models to interpolate required data from previously computed micro-scale simulations, thereby substantially reducing the number of micro-scale simulations. Nonetheless, HMC applications, though versatile, remain constrained by load balancing issues. We discuss two main issues: the a priori unknown and variable execution time of microscopic simulations, and the dynamic number of micro-scale simulations required. We tackle execution time variability using a pilot job mechanism to handle internal queuing and multiple sub-model execution on large-scale supercomputers, together with a data-informed execution time prediction model. To dynamically select the number of micro-scale simulations, the HMC pattern automatically detects and identifies three surrogate model phases that help control available and used core amount. After relevant phase detection and micro-scale simulation scheduling, any idle cores can be used for surrogate model update or for processor release back to the system. We demonstrate HMC performance by testing it on two representative multi-scale applications. We conclude that, considering the subtle interplay between the macroscale model, surrogate models and micro-scale simulations, HMC provides a promising path towards exascale for many multi-scale applications.
Published: 2019
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7. Toward High Fidelity Materials Property Prediction from Multiscale Modeling and Simulation

Author: Robin A. Richardson, James L. Suter, Maxime Vassaux, Robert C. Sinclair, Peter V. Coveney, Department of Chemistry [UCL, London], and University College of London [London] (UCL)
Subjects: Statistics and Probability, Computer science, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, [SPI.MAT]Engineering Sciences [physics]/Materials, [PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], High fidelity, Software, [PHYS.MECA.STRU]Physics [physics]/Mechanics [physics]/Structural mechanics [physics.class-ph], [PHYS.MECA.SOLID]Physics [physics]/Mechanics [physics]/Solid mechanics [physics.class-ph], [MATH.MATH-AP]Mathematics [math]/Analysis of PDEs [math.AP], Uncertainty quantification, Scaling, ComputingMilieux_MISCELLANEOUS, Numerical Analysis, Multidisciplinary, business.industry, Scale (chemistry), [PHYS.MECA.MSMECA]Physics [physics]/Mechanics [physics]/Materials and structures in mechanics [physics.class-ph], [INFO.INFO-NA]Computer Science [cs]/Numerical Analysis [cs.NA], 021001 nanoscience & nanotechnology, Supercomputer, Trial and error, Multiscale modeling, 0104 chemical sciences, Computer engineering, Modeling and Simulation, [SPI.GCIV.STRUCT]Engineering Sciences [physics]/Civil Engineering/Structures, [SPI.GCIV.MAT]Engineering Sciences [physics]/Civil Engineering/Matériaux composites et construction, 0210 nano-technology, business
Abstract: The current approach to materials discovery and design remains dominated by experimental testing, frequently based on little more than trial and error. With the advent of ever more powerful computers, rapid, reliable, and reproducible computer simulations are beginning to represent a feasible alternative. As high performance computing reaches the exascale, exploiting the resources efficiently presents interesting challenges and opportunities. Multiscale modeling and simulation of materials are extremely promising candidates for exploiting these resources based on the assumption of a separation of scales in the architectures of nanomaterials. Examples of hierarchical and concurrent multiscale approaches are presented which benefit from the weak scaling of monolithic applications, thereby efficiently exploiting large scale computational resources. Several multiscale techniques, incorporating the electronic to the continuum scale, which can be applied to the efficient design of a range of nanocomposites, are discussed. Then the work on the development of a software toolkit designed to provide verification, validation, and uncertainty quantification to support actionable prediction from such calculations is discussed.
Published: 2019
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8. X-ray physico-chemical imaging during activation of cobalt-based Fischer-Tropsch synthesis catalysts

Author: Beale, Andrew M., Jacques, Simon D. M., Di Michiel, Marco, Mosselmans, J. Frederick W., Price, Stephen W. T., Senecal, Pierre, Vamvakeros, Antonios, Paterson, James, Department of Chemistry [UCL, London], University College of London [London] (UCL), Research Complex at Harwell, European Synchrotron Radiation Facility (ESRF), and DIAMOND Light source
Subjects: [PHYS]Physics [physics], spectroscopy, IN-SITU, PHASE, scattering, MICROSCOPY, Articles, physico-chemical, cobalt, STATE, SIZE, TOMOGRAPHY, Fischer–Tropsch, RE, PARTICLE, Research Article
Abstract: International audience; The imaging of catalysts and other functional materials under reaction conditions has advanced significantly in recent years. The combination of the computed tomography (CT) approach with methods such as X-ray diffraction (XRD), X-ray fluorescence (XRF) and X-ray absorption near-edge spectroscopy (XANES) now enables local chemical and physical state information to be extracted from within the interiors of intact materials which are, by accident or design, inhomogeneous. In this work, we follow the phase evolution during the initial reduction step(s) to form Co metal, for Co-containing particles employed as Fischer-Tropsch synthesis (FTS) catalysts; firstly, working at small length scales (approx. micrometre spatial resolution), a combination of sample size and density allows for transmission of comparatively low energy signals enabling the recording of 'multimodal' tomography, i.e. simultaneous XRF-CT, XANES-CT and XRD-CT. Subsequently, we show high-energy XRD-CT can be employed to reveal extent of reduction and uniformity of crystallite size on millimetre-sized TiO2 trilobes. In both studies, the CoO phase is seen to persist or else evolve under particular operating conditions and we speculate as to why this is observed. This article is part of a discussion meeting issue 'Providing sustainable catalytic solutions for a rapidly changing world'.
Published: 2018
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9. H2 formation on interstellar dust grains:The viewpoints of theory, experiments, models and observations

Author: Pierre Guillard, Gunnar Nyman, Stéphanie Cazaux, Gianfranco Vidali, Valerio Pirronello, Valeska Valdivia, Valentine Wakelam, Naoki Watanabe, Sabine Morisset, Emeric Bron, Stephen D. Price, E. Habart, François Dulieu, Liv Hornekær, Cecile Gry, AMOR 2017, Laboratoire d'Astrophysique de Bordeaux [Pessac] (LAB), Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS Paris)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Marseille (LAM), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Institut d'Astrophysique de Paris (IAP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut d'astrophysique spatiale (IAS), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Physics and Astronomy [Aarhus], Aarhus University [Aarhus], Institut des Sciences Moléculaires d'Orsay (ISMO), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry [UCL, London], University College of London [London] (UCL), Astrophysique Interprétation Modélisation (AIM (UMR_7158 / UMR_E_9005 / UM_112)), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7), Institute of Low Temperature Science, Hokkaido University, Université de Bordeaux (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas [Madrid] (CSIC), Delft University of Technology (TU Delft), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université de Cergy Pontoise (UCP), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Interdisciplinary Nanoscience Center (iNANO), Laboratoire des Collisions Atomiques et Moléculaires, Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Sud Orsay, University of Gothenburg (GU), Università degli studi di Catania [Catania], Laboratoire de Radioastronomie (LRA), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Syracuse University (Physics Department), Syracuse University, Institute of Low Temperature Science [Sapporo], Hokkaido University [Sapporo, Japan], LERMA Cergy (LERMA), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Cergy Pontoise (UCP), Centre National D'Etudes Spatiales (France), Centre National de la Recherche Scientifique (France), Swedish Research Council, National Science Foundation (US), European Research Council, Science and Technology Facilities Council (UK), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS-PSL), Université Paris-Sud - Paris 11 (UP11)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National d’Études Spatiales [Paris] (CNES), Université Paris-Sud - Paris 11 (UP11)-Université Pierre et Marie Curie - Paris 6 (UPMC), Università degli studi di Catania = University of Catania (Unict), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, Astrochemistry, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], [SDU.ASTR.CO]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], Hydrogen molecule, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, 01 natural sciences, Grain surface chemistry, Astrobiology, Interstellar medium, Molecular hydrogen, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, Physical and Theoretical Chemistry, Astrochemistry, Molecular hydrogen, Grain surface chemistry, Interstellar medium, 010306 general physics, 010303 astronomy & astrophysics, Spectroscopy, Cosmic dust
Abstract: Molecular hydrogen is the most abundant molecule in the universe. It is the first one to form and survive photo-dissociation in tenuous environments. Its formation involves catalytic reactions on the surface of interstellar grains. The micro-physics of the formation process has been investigated intensively in the last 20 years, in parallel of new astrophysical observational and modeling progresses. In the perspectives of the probable revolution brought by the future satellite JWST, this article has been written to present what we think we know about the H formation in a variety of interstellar environments., VW’s research is funded by an ERC Starting Grant (3DICE, grant agreement 336474). GV acknowledges financial support from the National Science Foundation’s Astronomy & Astrophysics Division (Grants No. 1311958 and 1615897). LH acknowledges support from ERC Consolidator Grant GRANN (grant agreement no. 648551). GN acknowledges support from the Swedish Research Council. VW, FD and SM acknowledge the CNRS program ”Physique et Chimie du Milieu Interstellaire” (PCMI) co-funded bythe Centre National d’Etudes Spatiales (CNES). SDP acknowledges funding from STFC, UK. V.V acknowledges funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (MagneticYSOS project, grant agreement No 679937).
Published: 2017
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10. New insights into the structure and chemistry of Titan’s tholins via 13C and 15N solid state nuclear magnetic resonance spectroscopy

Author: Eric Quirico, Christian Bonhomme, F. Corà, Cyril Szopa, Chris J. Pickard, A. S. Rahman, Paul F. McMillan, C. Anquetil, C. Coelho, Sylvie Derenne, Biogéochimie et écologie des milieux continentaux (Bioemco), Centre National de la Recherche Scientifique (CNRS)-AgroParisTech-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Recherche Agronomique (INRA)-École normale supérieure - Paris (ENS Paris), Institut des matériaux de Paris-Centre (IMPC), ESPCI ParisTech-Ecole Nationale Supérieure de Chimie de Paris- Chimie ParisTech-PSL (ENSCP)-Université Pierre et Marie Curie - Paris 6 (UPMC), IMPEC - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry [UCL, London], University College of London [London] (UCL), Department of Physics and Astronomy [UCL London], Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Chimie de la Matière Condensée de Paris (site Paris VI) (LCMCP (site Paris VI)), Université Pierre et Marie Curie - Paris 6 (UPMC)-Collège de France (CdF)-Ecole Nationale Supérieure de Chimie de Paris- Chimie ParisTech-PSL (ENSCP)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-AgroParisTech-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Ecole Nationale Supérieure de Chimie de Paris - Chimie ParisTech-PSL (ENSCP), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), PLANETO - LATMOS, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG ), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Collège de France (CdF (institution))-Ecole Nationale Supérieure de Chimie de Paris - Chimie ParisTech-PSL (ENSCP), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Biogéochimie et écologie des milieux continentaux ( Bioemco ), École normale supérieure - Paris ( ENS Paris ) -Institut National de la Recherche Agronomique ( INRA ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -AgroParisTech-Université Paris-Est Créteil Val-de-Marne - Paris 12 ( UPEC UP12 ) -Centre National de la Recherche Scientifique ( CNRS ), Institut des matériaux de Paris-Centre ( IMPC ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Ecole Nationale Supérieure de Chimie de Paris- Chimie ParisTech-PSL ( ENSCP ) -ESPCI ParisTech, Laboratoire Atmosphères, Milieux, Observations Spatiales ( LATMOS ), Université de Versailles Saint-Quentin-en-Yvelines ( UVSQ ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université de Versailles Saint-Quentin-en-Yvelines ( UVSQ ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ), University College of London [London] ( UCL ), Institut de Planétologie et d'Astrophysique de Grenoble ( IPAG ), Observatoire des Sciences de l'Univers de Grenoble ( OSUG ), Université Joseph Fourier - Grenoble 1 ( UJF ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Grenoble Alpes ( UGA ) -Université Joseph Fourier - Grenoble 1 ( UJF ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Centre National de la Recherche Scientifique ( CNRS ) -Université Grenoble Alpes ( UGA ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire de Chimie de la Matière Condensée de Paris (site Paris VI) ( LCMCP (site Paris VI) ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Collège de France ( CdF ) -Ecole Nationale Supérieure de Chimie de Paris- Chimie ParisTech-PSL ( ENSCP ) -Centre National de la Recherche Scientifique ( CNRS ), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Recherche Agronomique (INRA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-AgroParisTech-Centre National de la Recherche Scientifique (CNRS), Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)
Subjects: Atmospheric chemistry, 010504 meteorology & atmospheric sciences, [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Chemical structure, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Ab initio, Electronic structure, Atmospheres, Chemistry, 01 natural sciences, symbols.namesake, Exobiology, 0103 physical sciences, Atmosphere of Titan, Spectroscopy, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Chemistry, Astronomy and Astrophysics, Tholin, [ SDU.ASTR.EP ] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], [ PHYS.ASTR.EP ] Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Cosmochemistry, Solid-state nuclear magnetic resonance, 13. Climate action, Space and Planetary Science, symbols, Physical chemistry, Titan, Titan (rocket family)
Abstract: International audience; Tholins are complex C,N-containing organic compounds produced in the laboratory. They are considered to provide materials that are analogous to those responsible for the haze observed in Titan's atmosphere. These compounds present an astrobiological interest due to their ability to release amino acids upon hydrolysis. Their chemical structure has been investigated using a large number of techniques. However, to date no detailed nuclear magnetic resonance (NMR) study has been performed on these materials despite the high potential of this technique for investigating the environment of given nuclei. Here 13C and 15N solid state NMR spectroscopy was applied to obtain new insights into the chemical structure of tholins produced through plasma discharge in gaseous N2-CH4 mixtures designed to simulate the atmosphere of Titan. Due to the low natural abundance of these isotopes, a 13C and 15N-enriched tholin sample was synthesized using isotopically enriched gas precursors. Various pulse sequences including 13C and 15N single pulse, 1H-13C and 1H-15N cross polarisation and 1H-15N-13C double cross polarisation were used. These techniques allowed complete characterisation of the chemical and structural environments of the carbon and nitrogen atoms. The NMR assignments were supplemented and confirmed by ab initio electronic structure calculations for model structures and molecular fragments.
Published: 2012
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11. Shock-induced transformation of olivine to a new metastable (Mg,Fe)2SiO4 polymorph in Martian meteorites

Author: Sandro Jahn, Bruno Reynard, Philippe Gillet, Pierre Beck, Paul F. McMillan, Bertrand Van de Moortèle, Mark Wilson, Laboratoire de Sciences de la Terre (LST), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Department of Chemistry [UCL, London], University College of London [London] (UCL), Davy-Faraday Research Laboratory, Royal Institution of Great Britain, GeoForschungsZentrum - Helmholtz-Zentrum Potsdam (GFZ), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), Department of Chemistry, UCL, Christopher Ingold Laboratories, Laboratoire de Planétologie de Grenoble (LPG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), and Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS)
Subjects: X-Ray-Diffraction, Lattice-Dynamics, HRTEM, 010504 meteorology & atmospheric sciences, Analytical chemistry, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Mineralogy, 550 - Earth sciences, zeta phase, transition phase, engineering.material, 010502 geochemistry & geophysics, Interaction Potentials, 01 natural sciences, Mantle (geology), chemistry.chemical_compound, [SDU.STU.PL]Sciences of the Universe [physics]/Earth Sciences/Planetology, Geochemistry and Petrology, Chondrite, Mg2Sio4, Earth and Planetary Sciences (miscellaneous), olivine, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Olivine, Beta-Phase Transformation, Raman-Spectroscopy, Spinelloid Phases, Wadsleyite, Silicate, Inelastic Neutron-Scattering, High-Temperature, Ringwoodite, Geophysics, chemistry, Meteorite, [SDU]Sciences of the Universe [physics], 13. Climate action, Space and Planetary Science, engineering, Mechanism, Molecular Dynamics simulation, Orthosilicate, Geology
Abstract: Transient high pressures and temperatures generated during meteor or asteroid impacts induce mineral phase transformations that can mimic those occurring at depth within the silicate mantle of terrestrial planets. Olivine (alpha-(Mg,Fe)(2)SiO4), the primary constituent of the Earth's upper mantle and of chondritic meteorites, transforms to the high-pressure polymorphs wadsleyite and ringwoodite (beta-, gamma-(Mg,Fe)(2)SiO4) that are observed in shocked chondrites. The observed phase transitions place constraints on the shock P-T conditions attained and they lead to models that describe the impact event. We studied the olivines present within two newly catalogued Martian meteorites NWA 2737 and NWA 1950 using micro-Raman spectroscopy and high-resolution transmission electron microscopy (HRTEM) techniques. The shock conditions were not sufficient to cause melting or transformation of the olivines into wadsleyite or ringwoodite (Mg,Fe)(2)SiO4. The shocked olivines are dark-coloured in hand specimen and thin section due to the presence of FexNiy, metallic nanoparticles formed during the shock. Molecular Dynamics simulations (MD) are consistent with the observation that the shocked olivines give rise to a new orthosilicate polymorph (zeta-(Mg,Fe)(2)SiO4) that is formed metastably during the shock process and that is subsequently recovered to ambient conditions. The presence of the new (Mg,Fe)(2)SiO4 polymorph in shocked ultrabasic rocks including meteorites may have remained undetected due to its structural and spectroscopic similarities with olivine. The existence of the metastable a- phase transition also allows rationalising previously unexplained results of shock compression experiments on olivines. zeta-(Mg,Fe)(2)SiO4 is also formed at ambient pressure as a metastable intermediate during back-transfon nation from wadsleyite. (c) 2007 Elsevier B.V. All rights reserved.
Published: 2007
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12. Lattice Vibrations and Spectroscopy of Mantle Phases

Author: Paul F. McMillan, Bruno Reynard, Razvan Caracas, Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), École normale supérieure - Lyon (ENS Lyon), Department of Chemistry [UCL, London], University College of London [London] (UCL), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), and École normale supérieure de Lyon (ENS de Lyon)
Subjects: Majorite, Olivine, 010504 meteorology & atmospheric sciences, Chemistry, Silicate perovskite, Mineralogy, Thermodynamics, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, engineering.material, 010502 geochemistry & geophysics, Wadsleyite, 01 natural sciences, Mantle (geology), Physics::Geophysics, Ringwoodite, 13. Climate action, [SDU]Sciences of the Universe [physics], Transition zone, engineering, Astrophysics::Earth and Planetary Astrophysics, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Stishovite
Abstract: Experimental vibrational spectroscopy studies combined with theoretical calculations are used to study and understand the lattice dynamics of minerals under the high-pressure–high-temperature conditions of the Earth's mantle. The results allow us to model and understand the thermodynamic properties, stability fields, and coexistence relations of mantle minerals. Theoretical basis and computational and experimental techniques for obtaining vibrational spectra are described. Applications to major silicates and their transitions that control the Earth's mantle structure are reviewed. Computational and experimental studies have focused on principal lower mantle and transition zone phases that are (Mg,Fe)O magnesiowustite, silicate perovskite, majorite, wadsleyite, ringwoodite, and SiO 2 stishovite. Results for their low-pressure counterparts olivine, pyroxene, and garnet phases that occur mainly within the upper mantle are presented. Lattice dynamics and phase transformations in aluminous and hydrous mineral phases are also described as they play an important role in governing water, radioactive element, and heat production distribution in the Earth's mantle.
Published: 2015

13. Critical Review of N, N+, N+ 2, N++, and N++ 2 Main Production Processes and Reactions of Relevance to Titan's Atmosphere

Author: Dutuit, Odile, Carrasco, Nathalie, Thissen, Roland, Vuitton, Véronique, Alcaraz, Christian, Pernot, Pascal, Balucani, Nadia, Casavecchia, Piergiorgio, Canosa, André, Le Picard, Sébastien D., Loison, Jean-Christophe, Herman, Zdenek, Zabka, Jan, Ascenzi, Daniela, Tosi, Paolo, Franceschi, Pietro, Price, Stephen D., Lavvas, Panayotis, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG ), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Space Research Institute of Austrian Academy of Sciences (IWF), Austrian Academy of Sciences (OeAW), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Chimie Physique D'Orsay (LCPO), Université Paris-Sud - Paris 11 (UP11)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Dipartimento di Chimica [Perugia], Università degli Studi di Perugia (UNIPG), Institut de Physique de Rennes (IPR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Centre National de la Recherche Scientifique (CNRS), Institut des Sciences Moléculaires (ISM), Centre National de la Recherche Scientifique (CNRS)-École Nationale Supérieure de Chimie et de Physique de Bordeaux (ENSCPB)-Université Sciences et Technologies - Bordeaux 1-Université Montesquieu - Bordeaux 4-Institut de Chimie du CNRS (INC), J. Heyrovský Institute of Physical Chemistry of the ASCR, Czech Academy of Sciences [Prague] (CAS), Dipartimento di Fisica [Povo], Università degli Studi di Trento (UNITN), IASMA Research and Innovation Centre, Istituto Agrario di San Michele All'Adige, Department of Chemistry [UCL, London], University College of London [London] (UCL), Groupe de spectrométrie moléculaire et atmosphérique (GSMA), Université de Reims Champagne-Ardenne (URCA)-Centre National de la Recherche Scientifique (CNRS), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), IMPEC - LATMOS, Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Université Montesquieu - Bordeaux 4-Université Sciences et Technologies - Bordeaux 1-École Nationale Supérieure de Chimie et de Physique de Bordeaux (ENSCPB)-Centre National de la Recherche Scientifique (CNRS), Czech Academy of Sciences [Prague] (ASCR), Università degli Studi di Perugia = University of Perugia (UNIPG), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), and Université Montesquieu - Bordeaux 4-Université Sciences et Technologies - Bordeaux 1 (UB)-École Nationale Supérieure de Chimie et de Physique de Bordeaux (ENSCPB)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: astrochemistry, dinitrogen processes, astrochemistry, Molecular data, [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Planets and satellites: atmospheres, Atomic processes, dinitrogen processes, Titan, Molecular processes, Atomic data
Abstract: International audience; This paper is a detailed critical review of the production processes and reactions of N, N+, N+ 2, N++, and N++ 2 of relevance to Titan's atmosphere. The review includes neutral, ion-molecule, and recombination reactions. The review covers all possible active nitrogen species under Titan's atmospheric conditions, specifically N2 (A3Σ+ u), N (4 S), N (2 D), N (2 P), N+ 2, N+ (3 P), N+ (1 D), N++ 2, and N++ species, and includes a critical survey of the reactions of N, N+, N+ 2, N++, and N++ 2 with N2, H2, D2, CH4, C2H2, C2H4, C2H6, C3H8 and the deuterated hydrocarbon analogs, as well as the recombination reactions of N+ 2, N+, N++ 2, and N++. Production processes, lifetimes, and quenching by collisions with N2 of all reactant species are reviewed. The N (4 S) state is reactive with radicals and its reactions with CH2, CH3, C2H3, and C2H5 are reviewed. Metastable states N2(A3Σ+u), N (2 D), and N (2 P) are either reactive or quenched by collisions with the target molecules reviewed. The reactions of N+ (1 D) have similar rate constants as N+ (3 P), but the product branching ratios differ significantly. Temperature effects and the role of the kinetic energy content of reactants are investigated. In all cases, experimental uncertainties of laboratory data are reported or estimated. Recommended values with uncertainties, or estimated values when no data are available, are given for rate constants and product branching ratios at 300 K and at the atmospheric temperature range of Titan (150-200 K for neutral reactions and 150 K for ion reactions).
Published: 2013
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14. Temperature- and light-induced spin crossover observed by x-ray spectroscopy on isolated Fe(II) complexes on gold

Author: Sandrine Heutz, Roberta Sessoli, Jenny C. Oberg, Patrick Rosa, Matteo Mannini, Ben Warner, Giordano Poneti, Cyrus F. Hirjibehedin, Fadi El Hallak, Marie-Anne Arrio, Philippe Sainctavit, Michele Serri, Tobias G. Gill, London Centre for Nanotechnology, University College of London [London] ( UCL ), Department of Physics and Astronomy [UCL London], Department of Chemistry [UCL, London], Department of Materials, Imperial College London, Institut de minéralogie et de physique des milieux condensés ( IMPMC ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -IPG PARIS-Université Paris Diderot - Paris 7 ( UPD7 ) -Centre National de la Recherche Scientifique ( CNRS ), Department of Chemistry 'Ugo Schiff', University of Florence Via della Lastruccia 3, Department of Applied Sciences and Technology, Guglielmo Marconi University, Institut de Chimie de la Matière Condensée de Bordeaux ( ICMCB ), Université de Bordeaux ( UB ) -Centre National de la Recherche Scientifique ( CNRS ), University College of London [London] (UCL), Institut de minéralogie et de physique des milieux condensés (IMPMC), Université Pierre et Marie Curie - Paris 6 (UPMC)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Università degli Studi di Firenze = University of Florence [Firenze], Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB), Université de Bordeaux (UB)-Centre National de la Recherche Scientifique (CNRS), Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS), Università degli Studi di Firenze = University of Florence [Firenze] (UNIFI), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut Polytechnique de Bordeaux-Université de Bordeaux (UB), ESRF for providing beam time under Projects HE3523 and HE3754, Institut de minéralogie, de physique des matériaux et de cosmochimie ( IMPMC ), Muséum National d'Histoire Naturelle ( MNHN ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut de recherche pour le développement [IRD] : UR206-Centre National de la Recherche Scientifique ( CNRS ), Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Centre National de la Recherche Scientifique (CNRS), Università degli Studi di Firenze = University of Florence (UniFI), and Université de Bordeaux (UB)-Institut Polytechnique de Bordeaux-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Absorption spectroscopy, Spin states, Nanotechnology, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Molecular physics, X-ray absorption, Spin crossover, Monolayer, Molecule, General Materials Science, Physical and Theoretical Chemistry, Multiplet, X-ray spectroscopy, Chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, Iron complexes, 021001 nanoscience & nanotechnology, 0104 chemical sciences, [ CHIM.MATE ] Chemical Sciences/Material chemistry, Absorption (chemistry), 0210 nano-technology, Submonolayer, UHV evaporation
Abstract: International audience; Using X-ray absorption techniques, we show that temperature- and light-induced spin crossover properties are conserved for a submonolayer of the [Fe(H2B(pz)2)2(2,2'-bipy)] complex evaporated onto a Au(111) surface. For a significant fraction of the molecules, we see changes in the absorption at the L2,3 edges that are consistent with those observed in bulk and thick film references. Assignment of these changes to spin crossover is further supported by multiplet calculations to simulate the X-ray absorption spectra. As others have observed in experiments on monolayer coverages, we find that many molecules in our submonolayer system remain pinned in one of the two spin states. Our results clearly demonstrate that temperature- and light-induced spin crossover is possible for isolated molecules on surfaces but that interactions with the surface may play a key role in determining when this can occur.
Published: 2013
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15. High-pressure structural transformations of Sn up to 138 GPa: Angle-dispersive synchrotron x-ray diffraction study

Author: Paul F. McMillan, Ashkan Salamat, Richard Briggs, Agnès Dewaele, Pierre Bouvier, Sylvain Petitgirard, Dominik Daisenberger, Gaston Garbarino, Furio Corà, Melissa E. Cutler, US Geological Survey [Golden], United States Geological Survey [Reston] (USGS), Laboratories of Applied Physics, California Institute of Technology (CALTECH), Laboratoire des matériaux et du génie physique (LMGP ), Institut National Polytechnique de Grenoble (INPG)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), European Synchrotron Radiation Facility (ESRF), Direction des Applications Militaires (DAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Department of Chemistry [UCL, London], University College of London [London] (UCL), and Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National Polytechnique de Grenoble (INPG)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Diffraction, Phase transition, Materials science, Condensed matter physics, 02 engineering and technology, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Potential energy, Electronic, Optical and Magnetic Materials, Crystal, Ab initio quantum chemistry methods, Phase (matter), 0103 physical sciences, Orthorhombic crystal system, Density functional theory, 010306 general physics, 0210 nano-technology
Abstract: The high-pressure behavior of elemental Sn has been studied by angle-dispersive synchrotron x-ray diffraction up to 138 GPa under quasihydrostatic conditions at room temperature. The data confirm the occurrence of a first-order phase transition at 10.8 GPa between $\ensuremath{\beta}$-Sn (Sn-II) ($I{4}_{1}/amd$) and a further body-centered-tetragonal polymorph ($\ensuremath{\gamma}$-Sn or Sn-III) ($I4/mmm$). Above 32 GPa, this phase exhibits a distortion into a new body-centered-orthorhombic (bco) modification ($Immm$). Beyond 70 GPa, the structure becomes body-centered cubic (bcc) ($Im\ensuremath{-}3m$). There is a region of coexistence where the bcc reflections are observed to appear superimposed on the bco pattern above 40 GPa and the two diffraction signatures coexist until 70 GPa. We examined this possible existence of a kinetically hindered first-order phase transition between the two polymorphs by performing density functional theory (DFT) calculations with an emphasis on the potential energy in response to axial ($c/a,b/a$) distortions at constant volume. The DFT results suggest a slightly different interpretation of the structural transformations. At low pressure, the global minimum energy is always centered around $b/a=1$, and there is no indication of transformation to a bco structure. However, any small strains in the $c/a$ ratio in the system would provide an orthorhombic distortion of the observed magnitude. Such strains could be induced due to slight deviations from hydrostatic conditions in the experimental study. Concerning the possible bco-bcc phase transitions, the DFT calculations reveal an energy surface with a barrier developed between solutions with different $c/a$ values over the pressure range of interest. Crucially, the calculated barrier heights are low, and they disappear in the region of the observed phase transformation. The DFT results indicate a mechanically softened material that may exhibit localized domain structures in response to even slightly nonhydrostatic stress conditions.
Published: 2013
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16. Synthesis of Tetragonal and Orthorhombic Polymorphs of Hf3N4 by High-Pressure Annealing of a Prestructured Nanocrystalline Precursor

Author: Andrew L. Hector, Simon A. J. Kimber, Pierre Bouvier, Benjamin M. Gray, Ashkan Salamat, Paul F. McMillan, European Synchrotron Radiation Facility (ESRF), Laboratoire des matériaux et du génie physique (LMGP ), Institut National Polytechnique de Grenoble (INPG)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry [UCL, London], and University College of London [London] (UCL)
Subjects: Chemistry, Annealing (metallurgy), Neutron diffraction, Nanotechnology, 02 engineering and technology, General Chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, Biochemistry, Article, Catalysis, Nanocrystalline material, 0104 chemical sciences, law.invention, Crystallography, Tetragonal crystal system, Colloid and Surface Chemistry, Oxidation state, law, Metastability, Orthorhombic crystal system, Crystallization, 0210 nano-technology
Abstract: International audience; Hf3N4 in nanocrystalline form is produced by solution phase reaction of Hf(NEtMe)(4) with ammonia followed by low-temperature pyrolysis in ammonia. Understanding of phase behavior in these systems is important because early transition-metal nitrides with the metal in maximum oxidation state are potential visible light photocatalysts. A combination of synchrotron powder X-ray diffraction and pair distribution function studies has been used to show this phase to have a tetragonally distorted fluorite structure with 1/3 vacancies on the anion sites. Laser heating nanocrystalline Hf3N4 at 12 GPa and 1500 K in a diamond anvil cell results in its crystallization with the same structure type, an interesting example of prestructuring of the phase during preparation of the precursor compound. This metastable pathway could provide a route to other new polymorphs of metal nitrides and to nitrogen-rich phases where they do not currently exist. Importantly it leads to bulk formation of the material rather than surface conversion as often occurs in elemental combination reactions at high pressure. Laser heating at 2000 K at a higher pressure of 19 GPa results in a further new polymorph of Hf3N4 that adopts an anion deficient cottunite-type (orthorhombic) structure. The orthorhombic Hf3N4 phase is recoverable to ambient pressure and the tetragonal phase is at least partially recoverable.
Published: 2013
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17. Spin crossover materials evaporated under clean high vacuum and ultra-high vacuum conditions: from thin films to single molecules

Author: Cyrus F. Hirjibehedin, Jenny C. Oberg, Titaniau Palamarciuc, Patrick Rosa, Sandrine Heutz, Fadi El Hallak, Jean-François Létard, Michele Serri, Institut de Chimie de la Matière Condensée de Bordeaux ( ICMCB ), Université de Bordeaux ( UB ) -Centre National de la Recherche Scientifique ( CNRS ), London Centre for Nanotechnology, University College of London [London] ( UCL ), Department of Physics and Astronomy [UCL London], Department of Chemistry [UCL, London], Department of Materials, Imperial College London, Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut Polytechnique de Bordeaux-Université de Bordeaux (UB), and University College of London [London] (UCL)
Subjects: Materials science, Vacuum, Thin films, Ultra-high vacuum, Nanoparticle, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Condensed Matter::Materials Science, Spin crossover, Materials Chemistry, Thin film, Materials, Condensed matter physics, Relaxation (NMR), General Chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, Molecules, 021001 nanoscience & nanotechnology, Evaporation (deposition), 0104 chemical sciences, Hysteresis, Nanocrystal, [ CHIM.MATE ] Chemical Sciences/Material chemistry, 0210 nano-technology
Abstract: International audience; We report clean evaporation under ultra-high vacuum conditions of two spin crossover materials, yielding either microcrystallites or homogeneous thin films. Magnetic and photomagnetic studies show that thermal and light-induced spin crossover properties are preserved. Preliminary STM imaging of sub-monolayers indicates that the deposited molecules remain intact on the surface.
Published: 2012
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18. Composition and polyamorphism in supercooled yttria–alumina melts

Author: Louis Hennet, Odile Majérus, Chris J. Benmore, G. N. Greaves, Q. Vu Van, Paul F. McMillan, D. P. Langstaff, Martin Wilding, Florian Kargl, J. K. R. Weber, Conditions Extrêmes et Matériaux : Haute Température et Irradiation (CEMHTI), Université d'Orléans (UO)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Argonne National Laboratory [Lemont] (ANL), Laboratoire de Chimie Appliquée de l'État Solide (LCAES), Ecole Nationale Supérieure de Chimie de Paris - Chimie ParisTech-PSL (ENSCP), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry [UCL, London], and University College of London [London] (UCL)
Subjects: Critical phenomena, Thermodynamics, 02 engineering and technology, Kinetic energy, 01 natural sciences, Physics::Fluid Dynamics, Polyamorphism, 0103 physical sciences, Thermal, Phases and equilibria, Materials Chemistry, Fluctuations, 010306 general physics, Supercooling, Yttria-stabilized zirconia, ComputingMilieux_MISCELLANEOUS, Chemistry, Transition temperature, Structure, Diffraction and scattering measurements, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Electronic, Optical and Magnetic Materials, Condensed Matter::Soft Condensed Matter, Glass formation, Ceramics and Composites, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Supercooled liquids, 0210 nano-technology, Structure factor
Abstract: By extending recent work on liquid–liquid transitions in supercooled yttria–alumina AYx liquids we draw attention to the compositional dependence of the structure factor of the high density liquid, arguing that this is sufficiently sensitive to discriminate between liquids at the level of a few %. Comparing structure factor differences between liquids of different compositions and in the same liquid AY20 between high and low temperatures straddling the transition at 1788 K between a high density liquid (HDL) and a low density liquid (LDL) enables compositional phase separation to be ruled out. It points instead to kinetic changes in polyhedral configurational order being the drivers for this polyamorphic transformation. Rotor behaviour observed in levitated liquid drops used in the high temperature experiments enables the reversibility of the LLT transition (LLT) and the associated changes in entropy and density to be identified. Evidence for critical-like behaviour in the structural relaxation time and in the fluctuation correlation length is presented. By re-examining recent work which failed to find the structural and thermal signatures for the LLT in liquid AY20 at 1788 K we present evidence for the LLT occurring instead in liquid AY15 at 1940 K, suggesting that the liquid-liquid transition temperature in AYx liquids decreases with increasing yttria content.
Published: 2011
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19. Dense close-packed phase of tin above 157 GPa observed experimentally via angle-dispersive x-ray diffraction

Author: Agnès Dewaele, Sylvain Petitgirard, Gaston Garbarino, Ashkan Salamat, Chris J. Pickard, Paul F. McMillan, Mohamed Mezouar, Pierre Bouvier, European Synchrotron Radiation Facility ( ESRF ), Direction des Applications Militaires ( DAM ), Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ), Laboratoire des matériaux et du génie physique ( LMGP ), Institut National Polytechnique de Grenoble ( INPG ) -Centre National de la Recherche Scientifique ( CNRS ) -Institut polytechnique de Grenoble - Grenoble Institute of Technology ( Grenoble INP ), Department of Physics and Astronomy [UCL London], University College of London [London] ( UCL ), Department of Chemistry [UCL, London], European Synchrotron Radiation Facility (ESRF), Direction des Applications Militaires (DAM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire des matériaux et du génie physique (LMGP ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National Polytechnique de Grenoble (INPG)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), University College of London [London] (UCL), and Institut National Polytechnique de Grenoble (INPG)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Diffraction, Phase transition, Materials science, Ab initio, chemistry.chemical_element, [CHIM.MATE]Chemical Sciences/Material chemistry, 02 engineering and technology, Crystal structure, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 01 natural sciences, Electronic, Optical and Magnetic Materials, Pressure range, Crystallography, chemistry, Phase (matter), [ CHIM.MATE ] Chemical Sciences/Material chemistry, 0103 physical sciences, X-ray crystallography, 010306 general physics, 0210 nano-technology, Tin, ComputingMilieux_MISCELLANEOUS
Abstract: A hexagonal close-packed ($P63/mmc$) phase of the group 14 element Sn has been observed using angle-dispersive x-ray diffraction. The phase transition proceeds from $\text{bcc}\ensuremath{\rightarrow}\text{hcp}$ above 157 GPa at 298 K via a first-order pathway, accompanied by a small decrease in unit-cell volume (0.2%). Both phases coexist up to 194 GPa. Ab initio random structure search calculations confirm that the hcp phase is the only candidate for another polymorph of Sn occurring in this pressure range, and predict a return to the bcc structure above 1.3 TPa.
Published: 2011
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20. High-pressure phase transformations, pressure-induced amorphization, and polyamorphic transition of the clathrate Rb6.15Si46

Author: Machon, D., Toulemonde, Pierre, Mcmillan, P. F., Amboage, M., Munoz, A., Rodríguez-Hernández, P., San Miguel, A., Laboratoire de Physique de la Matière Condensée et Nanostructures (LPMCN), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon, Matériaux, Rayonnements, Structure (MRS), Institut Néel (NEEL), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry [UCL, London], University College of London [London] (UCL), European Synchrotron Radiation Facility (ESRF), DIAMOND Light source, Departamento de Física Fundamental II, MALTA Consolider Team, and Departamento de Física Fundamental II, MALTA Consolider Team, and Instituto de Materiales y Nanotecnología, Universidad de La Laguna
Subjects: [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], 61.50.Ks, 64.60.My
Abstract: International audience; The type-I clathrate Rb6.15Si46 with partly empty cage sites has been studied up to 36 GPa using Raman spectroscopy, synchrotron x-ray diffraction in diamond-anvil cells, and ab initio total-energy and lattice-dynamics calculations. A first phase transition is observed at 13±1 GPa and a "volume collapse" transition within the clathrate structure is then observed at 24±1 GPa. Pressure-induced amorphization into a high-density amorphous (HDA) state occurs above P=33±1 GPa. The HDA form transforms into a low-density amorphous polymorph during decompression. During the compression study using angle dispersive synchrotron x-ray diffraction techniques we measured bulk modulus parameters for rocksalt-structured TaO, included adventitiously in the clathrate sample [K0=293(3) GPa and K′0=5.4(3)].
Published: 2009
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21. Tholins and their relevance for astrophysical issues

Author: Bruno Reynard, Victoria Lees, Gilles Montagnac, Cyril Szopa, Bernard Schmitt, Guy Cernogora, Sylvie Derenne, P. Coll, Jean-Noël Rouzaud, Nicolas Fray, Paul F. McMillan, François Raulin, Eric Quirico, B. Minard, Laboratoire de Planétologie de Grenoble (LPG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Service d'aéronomie (SA), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry [UCL, London], University College of London [London] (UCL), Biogéochimie et écologie des milieux continentaux (Bioemco), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Recherche Agronomique (INRA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-AgroParisTech-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Sciences de la Terre (LST), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de géologie de l'ENS (LGENS), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry, The Pennsylvania State University, Pennsylvania State University (Penn State), Penn State System-Penn State System, Sun Kwok & Scott A. Sandford, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-AgroParisTech-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Centre National de la Recherche Scientifique (CNRS)-AgroParisTech-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Recherche Agronomique (INRA)-École normale supérieure - Paris (ENS Paris), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Laboratoire de géologie de l'ENS (LGE), École normale supérieure - Paris (ENS Paris)-École normale supérieure - Paris (ENS Paris), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Institut national des sciences de l'Univers (INSU - CNRS), and Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)
Subjects: 010504 meteorology & atmospheric sciences, chemistry.chemical_element, Astrophysics, 01 natural sciences, Astrobiology, symbols.namesake, Interplanetary dust cloud, Chondrite, 0103 physical sciences, Comets, 010303 astronomy & astrophysics, Chemical composition, Refractory (planetary science), 0105 earth and related environmental sciences, organic matter, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Astronomy and Astrophysics, Tholin, chondrites, chemistry, 13. Climate action, Space and Planetary Science, symbols, Absorption (chemistry), Titan (rocket family), Carbon, tholins
Abstract: Tholins are polymeric hydrogenated carbon nitrides formed from N2:CH4 mixtures exposed to electrical discharges. They are complex disordered solids, and their structural chemistry and formation processes are not yet fully understood. Tholins have been widely adopted as useful analogs of reddish organic solids associated with planetary bodies or in interstellar space (e.g., Titan's aerosols, reddish surfaces of outer objects, interstellar organics, etc.) for fitting astronomical observations. However, there has been little evidence to date that they in fact constitute pertinent model materials, i. e. with chemical structure/composition similar to those presumed to be present in planetary or interstellar organic solids. In this contribution, we first review recent advances made regarding the determination of composition and structure of tholins produced in the laboratory. They point to a high chemical selectivity in the range of functional groups present, the control of unsaturation by nitrogen, and the highly disordered character of the structures. In a second section, we discuss the relationship between chemistry and the optical properties of tholins, and we point out the lack of a unique relationship between the shape and strength of the visible absorption bands and the chemical composition or structure of the model tholins. The tholins exhibit similarities with HCN “polymers”, that are suspected to be present in cometary refractory dust. This points to the existence of possible similar polymerisation processes, and it suggests they could also be used as analogs of N-rich cometary organics. Laboratory-based studies of cometary dust might offer new insights on the “chemical relevancy” of tholins, as combined micro-analytical techniques will allow direct comparison of chemical information between the materials produced. In a third section we present recent results pertaining to the search for such compounds in cometary grains (Stardust grains, interplanetary dust particles - IDPs). We show that some N-rich spots in stratospheric IDPs are rich in cyanide species, but no tholin-like compounds or polymeric HCN have been detected to date.
Published: 2008
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22. New experimental constraints on the composition and structure of tholins

Author: Patrick Simon, Bernard Schmitt, Bruno Reynard, Victoria Lees, Guy Cernogora, J. M. Bernard, Nicolas Fray, Paul F. McMillan, Cyril Szopa, Jean-Noël Rouzaud, Robert D. Minard, Gilles Montagnac, Eric Quirico, François Raulin, Patrice Coll, Laboratoire de Planétologie de Grenoble (LPG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Sciences de la Terre (LST), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry [UCL, London], University College of London [London] (UCL), Service d'aéronomie (SA), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de géologie de l'ENS (LGENS), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Conditions Extrêmes et Matériaux : Haute Température et Irradiation (CEMHTI), Université d'Orléans (UO)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry, The Pennsylvania State University, Pennsylvania State University (Penn State), Penn State System-Penn State System, École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Laboratoire de géologie de l'ENS (LGE), École normale supérieure - Paris (ENS Paris)-École normale supérieure - Paris (ENS Paris), Centre National de la Recherche Scientifique (CNRS)-Université d'Orléans (UO), and Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, Atmospheric chemistry, 010504 meteorology & atmospheric sciences, Analytical chemistry, Infrared spectroscopy, 01 natural sciences, chemistry.chemical_compound, symbols.namesake, 0103 physical sciences, High-resolution transmission electron microscopy, Spectroscopy, 010303 astronomy & astrophysics, Carbon nitride, Alkyl, 0105 earth and related environmental sciences, chemistry.chemical_classification, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, X-ray spectroscopy, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Astronomy and Astrophysics, Tholin, chemistry, Space and Planetary Science, symbols, Raman spectroscopy, Titan
Abstract: International audience; Powdered samples of carbon–nitrogen-hydrogen “tholins” that mimic Titan's atmosphere aerosols were produced under levitation conditions in the laboratory with a dusty plasma (PAMPRE experiment) using different initial N2:CH4 gas mixtures and studied using UV Raman and infrared spectroscopy, X-ray diffraction and high resolution transmission electron microscopy (HRTEM). Comparison between the tholins produced in the PAMPRE experiments and samples prepared by other techniques reveal that they form a fairly homogeneous family of hydrogenated carbon nitride materials. Wall effects during the PAMPRE deposition experiments and other were found to have little effect on the chemical structure of tholins. The first-order UV Raman bands of the disordered carbonaceous materials point to a large contribution of sp2 clusters present compared with olefinic Cdouble bond; length as m-dashN or Cdouble bond; length as m-dashC groupings, whereas features at 690 and 980 cm−1 suggest C3N3 rings are present as a species inserted in the macromolecular network. Diffraction techniques do not indicate the presence of large polyaromatic species in any of the tholins studied, whatever their nitrogen concentration, in disagreement with certain previous observations. This precludes the idea that the nature and degree of absorption in the visible range is controlled by the size of polyaromatic species, as has been observed in series of carbon-based materials obtained via thermal processing. Infrared spectroscopy analysis of the tholins has confirmed earlier identifications of chemical groups present including primary amines, nitriles, and alkyl moieties such as CH2/CH3, but has ruled out CH2/CH3 branches appearing on secondary or tertiary amines. Similar analyses were also performed on a polymeric (HCN)x material, which was found to present several similarities with the tholins, hence suggesting similar polymerization processes.
Published: 2008
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23. Spectroscopic studies of Titan's tholins and implications for titan's surface

Author: Quirico, Eric, Lees, V., Montagnac, Gilles, Reynard, Bruno, Mc Millan, P., Szopa, Cyril, Cernogora, Guy, Rouzaud, Jean-Noel, Bernard, Jean-Michel, Fray, N., Schmitt, Bernard, Coll, Patrice, Raulin, François, Minard, B., Laboratoire de Planétologie de Grenoble (LPG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry [UCL, London], University College of London [London] (UCL), Laboratoire de Sciences de la Terre (LST), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Service d'aéronomie (SA), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Laboratoire de géologie de l'ENS (LGE), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris)-École normale supérieure - Paris (ENS Paris), Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Pibaret-Bourdon, Béatrice, École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de géologie de l'ENS (LGENS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris)
Subjects: [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], [SDU.ASTR] Sciences of the Universe [physics]/Astrophysics [astro-ph]
Published: 2007

24. Dissociative double photoionization of N2 using synchrotron radiation: Appearance energy of the N2+ dication

Author: Jana Roithová, Daniela Ascenzi, Monica de Simone, Pietro Franceschi, Ján Žabka, Marcello Coreno, Paolo Tosi, Claire L. Ricketts, Roland Thissen, Dipartimento di Fisica [Povo], Università degli Studi di Trento (UNITN), Laboratoire de Chimie Physique D'Orsay (LCPO), Université Paris-Sud - Paris 11 (UP11)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), V. Čermák Laboratory, Czech Academy of Sciences [Prague] (CAS)-J. Heyrovsky Institute of Physical Chemistry, Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences (IOCB / CAS), Czech Academy of Sciences [Prague] (CAS), Department of Chemistry [UCL, London], University College of London [London] (UCL), Laboratorio Nazionale TASC, INFM-CNR, Istituto di Metodologie Inorganiche e di Plasmi (IMIP)-CNR (IMIP-CNR), and IMIP-CNR
Subjects: DIATOMIC-MOLECULES, General Physics and Astronomy, 02 engineering and technology, Photoionization, UPPER-ATMOSPHERE, Photon energy, Kinetic energy, 01 natural sciences, 7. Clean energy, Ion, CROSS-SECTIONS, 0103 physical sciences, Physical and Theoretical Chemistry, 010306 general physics, IONIZED MOLECULES, ANGULAR-DISTRIBUTIONS, Chemistry, ELECTRON-IMPACT IONIZATION, Coulomb explosion, Appearance energy, 021001 nanoscience & nanotechnology, Potential energy, Dication, COULOMB EXPLOSION, Atomic physics, 0210 nano-technology, ION COINCIDENCE, HIGH-RESOLUTION, KINETIC-ENERGY
Abstract: Photoionization cross sections for the production of the doubly charged ion N2+ from N-2 have been measured by means of synchrotron radiation in the photon energy range from 50 to 110 eV. The appearance energy for N2+ has been determined as 55.2 +/- 0.2 eV, i.e., about 1.3 eV higher than the spectroscopic dissociation limit leading to the charge asymmetric dissociation channel N2+(P-2)+N(S-4) at 53.9 eV. The onset of a second threshold at 59.9 +/- 0.2 eV is detected and the energy dependence of photoion intensities near the threshold regions is interpreted in terms of the Wannier theory. The production of the N2+ dication is discussed in terms of direct and indirect mechanisms for dissociative charge asymmetric photoionization and by comparison with the potential energy curves of the intermediate N-2(2+) dication. Experimental evidences for the opening of the Coulomb explosion channel N2++N+ at high photon energies are provided by measuring the kinetic energy release spectra of N2+ fragments at selected photon energies. (c) 2007 American Institute of Physics.
Published: 2007
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25. Investigation of the chemical structure and optical properties of Titan's tholins and 'HCN polymer' by spectral analyses. Implications for the analysis of Cassini-Huygens observations and refractory organics in cometary grains

Author: Quirico, Eric, Bernard, Jean-Michel, Montagnac, Gilles, Rouzaud, Jean-Noel, Szopa, Cyril, Cernogora, Guy, Reynard, B., Mc Millan, P., Fray, N., Schmitt, Bernard, Coll, Patrice, Raulin, François, Laboratoire de Planétologie de Grenoble (LPG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Sciences de la Terre (LST), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Service d'aéronomie (SA), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Laboratoire de géologie de l'ENS (LGE), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris)-École normale supérieure - Paris (ENS Paris), Department of Chemistry [UCL, London], University College of London [London] (UCL), Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de géologie de l'ENS (LGENS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Pibaret-Bourdon, Béatrice, École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris)
Subjects: [SDU] Sciences of the Universe [physics], [SDU]Sciences of the Universe [physics]
Abstract: Meeting abstract from the CDROM, #2457; Tholins and HCN polymer are used as analogues of Titan s aerosols and N-rich cometary refractory organics respectively 1 2 The chemical structure of these compounds is up to now not elucidate as well as the identification of the parameters which do control their optical properties This study provides new clues on the chemical structure of these compounds and we discuss some implications for the analysis of spectral data of Titan and other icy satellites possibly covered by complex organics Tholins produced from two different experiments located in Service d Aeronomie Verrieres-le-buisson - France and in LISA Creteil France and HCN polymer samples 1 3 4 5 were studied by UV Raman spectroscopy 5 6 High Resolution Transmission Electron Microscopy and Infrared spectroscopy 7 Our study show that all samples are hydrogenated carbon nitrides They exhibit similar sp2 structures this latter being the key factor controlling the optical properties in the visible and near infrared spectral ranges 5 Tholins formed from the different experiments are roughly similar but they exhibit compositional differences which demonstrate that the derivation of physical parameters from remote sensing data may be extremely difficult or even impossible HCN polymer has a chemical structure similar to tholins and strictly speaking cannot be considered as a polymer Its identification in cometary grains can be performed using UV Raman spectrometry We will present the structural analysis new reflectance spectral data of these samples and we will discuss their implications for analysing spectral data of the surfaces of icy satellites, in particular Titan.
Published: 2006

26. Chemical Structure and Optical Properties of Titan's Tholins and HCN Polymer. Implications for the Analysis of Cassini-Huygens Observations and Refractory Organics in Cometary Grains

Author: Quirico, Eric, Bernard, Jean-Michel, Montagnac, Gilles, Rouzaud, Jean-Noel, Szopa, Cyril, Cernogora, Guy, Reynard, Bruno, Mc Millan, P., Fray, N., Schmitt, Bernard, Coll, Patrice, Raulin, François, Laboratoire de Planétologie de Grenoble (LPG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Sciences de la Terre (LST), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de géologie de l'ENS (LGENS), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Service d'aéronomie (SA), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry [UCL, London], University College of London [London] (UCL), Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Pibaret-Bourdon, Béatrice, Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Laboratoire de géologie de l'ENS (LGE), École normale supérieure - Paris (ENS Paris)-École normale supérieure - Paris (ENS Paris), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], [SDU.ASTR] Sciences of the Universe [physics]/Astrophysics [astro-ph]
Abstract: International audience; Tholins and HCN polymers were studied by UV Raman spectroscopy and High Resolution Transmission Electron Microscopy. Both have very close chemical structure. HCN polymer could be easily identified in cometary grains by UV Raman spectroscopy.
Published: 2006

27. Laboratory experiments required for interpreting Cassini-Huygens data

Author: Bernard, Jean-Michel, Quirico, Eric, Schmitt, Bernard, Coll, P., Nguyen, M.-J., Raulin, F., Szopa, Cyril, Cernogora, Guy, Montagnac, Gilles, Reynard, Bruno, Derenne, S., Mc Millan, P., Rouzaud, Jean-Noel, Laboratoire de Planétologie de Grenoble (LPG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Service d'aéronomie (SA), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Sciences de la Terre (LST), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Biogéochimie et écologie des milieux continentaux (Bioemco), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-AgroParisTech-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry [UCL, London], University College of London [London] (UCL), Laboratoire de géologie de l'ENS (LGENS), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Pibaret-Bourdon, Béatrice, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Recherche Agronomique (INRA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-AgroParisTech-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Centre National de la Recherche Scientifique (CNRS)-AgroParisTech-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Recherche Agronomique (INRA)-École normale supérieure - Paris (ENS Paris), Laboratoire de géologie de l'ENS (LGE), École normale supérieure - Paris (ENS Paris)-École normale supérieure - Paris (ENS Paris), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), and Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Institut national des sciences de l'Univers (INSU - CNRS)
Subjects: [SDU] Sciences of the Universe [physics], [SDU]Sciences of the Universe [physics], ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2005

28. Using Titan's tholins and condensates produced in laboratory for interpreting Cassini-Huygens data

Author: Bernard, Jean-Michel, Quirico, Eric, Schmitt, Bernard, Coll, P., Nguyen, M.-J., Montagnac, Gilles, Reynard, Bruno, Derenne, S., Mc Millan, P., Rouzaud, Jean-Noel, Szopa, Cyril, Cernogora, Guy, Laboratoire de Planétologie de Grenoble (LPG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Institut national des sciences de l'Univers (INSU - CNRS), Laboratoire de Sciences de la Terre (LST), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Biogéochimie et écologie des milieux continentaux (Bioemco), Centre National de la Recherche Scientifique (CNRS)-AgroParisTech-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Recherche Agronomique (INRA)-École normale supérieure - Paris (ENS Paris), Department of Chemistry [UCL, London], University College of London [London] (UCL), Laboratoire de géologie de l'ENS (LGE), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris)-École normale supérieure - Paris (ENS Paris), Service d'aéronomie (SA), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-AgroParisTech-Centre National de la Recherche Scientifique (CNRS), Laboratoire de géologie de l'ENS (LGENS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Pibaret-Bourdon, Béatrice, Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Recherche Agronomique (INRA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-AgroParisTech-Centre National de la Recherche Scientifique (CNRS), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris)
Subjects: [SDU] Sciences of the Universe [physics], [SDU]Sciences of the Universe [physics]
Abstract: EGU05-A-06887; Titan, the largest satellite of Saturn, has been studied as an exo/astrobiological object for several years. Its dense atmosphere is made of nitrogen with a few percent of methane. Subjected to UV and energetic particle bombardments (incoming from solar radiations and Saturn's magnetosphere), hydrocarbons, nitriles (like HCN, a precursor of amino-acids) and organic aerosols are produced inside the atmosphere in significant amounts. These aerosols then accumulate on the surface. Currently, the aerosols composition and structure and their production are unknown, whereas they play a key role in the chemistry and energy balance of Titan's atmosphere. The DISR and CIRS instruments onboard the Cassini-Huygens mission have returned and/or are returning spectroscopic data from Titan's atmosphere and surface. The analysis of these data requires the visible and infrared optical properties of 1) Titan's aerosols analogues such as the so-called "tholins" and 2) potential solid or liquid condensates composed with various molecules (HCN, CH3CN,...). It also requires, especially for tholins, an accurate chemical and physical characterization in order to derive spectral tracers, and to establish the relevancy of these analogues. We have initiated a study which associates different analytical techniques including macroscopic and micro-FTIR, Raman micro-spectroscopy, Nuclear Magnetic Resonance and High Resolution Electron Microscopy. The first results of this study will be presented along with their use for interpreting spectroscopic data from the Cassini-Huygens mission. This work is supported by a grant from CNES (Centre National d'Etudes Spatiales) in France.
Published: 2005

29. Cassini-Huygens mission : which tholins for simulating Titan's aerosols ?

Author: Bernard, Jean-Michel, Quirico, Eric, Montagnac, Gilles, Reynard, Bruno, Derenne, S., Coll, P., Nguyen, M.-J., Szopa, Cyril, Cernogora, Guy, Mc Millan, P., Rouzaud, Jean-Noel, Schmitt, Bernard, Laboratoire de Planétologie de Grenoble (LPG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Sciences de la Terre (LST), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Biogéochimie et écologie des milieux continentaux (Bioemco), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-AgroParisTech-Centre National de la Recherche Scientifique (CNRS), Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Service d'aéronomie (SA), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Chemistry [UCL, London], University College of London [London] (UCL), Laboratoire de géologie de l'ENS (LGENS), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Pibaret-Bourdon, Béatrice, École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Recherche Agronomique (INRA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-AgroParisTech-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Centre National de la Recherche Scientifique (CNRS)-AgroParisTech-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Recherche Agronomique (INRA)-École normale supérieure - Paris (ENS Paris), Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Laboratoire de géologie de l'ENS (LGE), École normale supérieure - Paris (ENS Paris)-École normale supérieure - Paris (ENS Paris), and Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Institut national des sciences de l'Univers (INSU - CNRS)
Subjects: [SDU] Sciences of the Universe [physics], [SDU]Sciences of the Universe [physics]
Abstract: EGU05-A-06802; The exploration of Titan by the CASSINI-HUYGENS mission includes different spectrometers covering the visible and infrared ranges, which will probe the atmosphere (e.g. CIRS, DISR) and the surface (DISR). The analysis of these spectroscopic data requires the optical constant of analogue materials of Titan's aerosols. Titan's tholins, produced in laboratory from N2:CH4 mixtures in cold plasma, are considered as the best analogues available to date. However, large compositional and morphological variations are reported among tholins produced from different experiments, and even within the same experiment. Different attempts have been made in order to better constrain the factors controlling tholin's composition, but no systematic studies have been performed for determining the links between the spectroscopic properties and the chemical composition. This study focuses on the chemical characterization of tholins at the micrometric scale, by using different analytical techniques, and attempts to correlate the chemical information wih the infrared spectral properties.
Published: 2005

30. Impact of functionalized linkers on the energy landscape of ZIFs

Author: Caroline Mellot-Draznieks, Benoit Creton, Raimondas Galvelis, Ben Slater, Robin Chaudret, Carlos Nieto-Draghi, Department of Chemistry, Department of Chemistry [UCL, London], University College of London [London] (UCL)-University College of London [London] (UCL), IFP Energies nouvelles (IFPEN), Laboratoire de Chimie des Processus Biologiques (LCPB), and Université Pierre et Marie Curie - Paris 6 (UPMC)-Collège de France (CdF (institution))-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Work (thermodynamics), Quantitative structure–activity relationship, Zeolitic imidazolate frameworks, Nanotechnology, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, chemistry.chemical_compound, Linker, Imidazolate, Cluster (physics), ZIFs, General Materials Science, Topology (chemistry), Energy landscape, [CHIM.MATE]Chemical Sciences/Material chemistry, General Chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, 0104 chemical sciences, chemistry, Chemical physics, Chemical stability, [CHIM.OTHE]Chemical Sciences/Other, 0210 nano-technology, Zeolitic imidazolate framework
Abstract: International audience; Zeolitic imidazolate frameworks (ZIFs) are well-known for their thermal and chemical stability, as well as for their structural diversity reminiscent of those found in the realm of zeolites. Linker-linker interactions were recognized as essential in the discovery of new topologies through the choice of substituted imidazolates. However, the impact of the linker through modification of the imidazolate's substituents on the energy landscape of ZIFs remains to be rationalized. In this work, LiB-based ZIFs serve as model crystal structures to explore the impact of linker-linker interactions, varying the number and position of methyl groups. The study focuses on the characteristics of experimental and hypothetical structures studied by first principle DFT-D calculations, and further interpreted through QSPR and Non covalent interaction (NCI) analysis. We provide an empirical QSPR model accounting for linker and topology effects on the stability of the frameworks. Both the position and number of substituents on the imidazolate linkers have a profound impact on the energy landscape of ZIFs, reshuffling the ranking of stabilized versus less stable topologies that were otherwise almost isoenergetic with unsubstituted imidazolate. NCI analysis revealed that methyl substituents induce repulsive interactions within the boron-centred cluster that are compensated by attractive non-bonded interactions at the larger scale of the solid. Besides the kinetic factors at play in ZIF synthesis which are difficult to consider from a modelling perspective, our calculations show that thermodynamic considerations are at work, explaining the intractability of certain topologies with certain linkers. Our calculations provide insight into the magnitude of the thermodynamic penalties that must be overcome in order to form particular topologies and the energy scale that needs to be overcome to generate lower density materials - a target for many experimental groups. The identified dominant linker-linker interactions could be exploited to overcome the limitations of current synthesis techniques.
Published: 2013
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31. Reflectance spectra and chemical structure of Titan's tholins: Application to the analysis of Cassini–Huygens observations

Author: Reynard, Bruno, Bernard, J.-P., Quirico, E., Brissaud, O., MONTAGNAC, O, Reynard, E., MCMILLAN, P, COLL, O, NGUYEN, E, Raulin, F., Schmitt, B., Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de recherche en astrophysique et planétologie (IRAP), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Planétologie de Grenoble (LPG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Géographie - Lausanne (IGUL), Université de Lausanne (UNIL), Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Sciences de la Terre (LST), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Department of Chemistry [UCL, London], University College of London [London] (UCL), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Centre National de la Recherche Scientifique (CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)
Subjects: Solar System, Materials science, 010504 meteorology & atmospheric sciences, Satellites, Infrared spectroscopy, Organic chemistry, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, surfaces, 01 natural sciences, Spectral line, Astrobiology, symbols.namesake, [SDU.STU.PL]Sciences of the Universe [physics]/Earth Sciences/Planetology, 0103 physical sciences, Spectroscopy, 010303 astronomy & astrophysics, Stratosphere, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Remote sensing, Astronomy and Astrophysics, Tholin, Aerosol, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], symbols, Titan (rocket family), Titan
Abstract: International audience; Titan's tholins are used as analogs of Titan's aerosols and N-rich organic solids present on many icy surfaces. However, it is not clear whether or not they are relevant analogs, and which kind of tholins should be used among a wide set available in literature. This paper presents reflectance spectral data of two tholins selected as end-members of a series of samples covering a very wide range of continuous chemical and optical properties. These samples were formed under experimental conditions fairly consistent with Titan's stratosphere. A general framework for using these laboratory data to the analysis of spectral observation of Titan's surface or other objects is suggested. Furthermore, the study reports the first in situ unambiguous identification of aromatics compounds and evidences variations in the sp2 carbon structure, which controls the absorption properties in the visible/NIR. These results also point out it is very unlikely to derive quantitative chemical information (e.g., N content, sp2/sp3 ratio) from remote sensing reflectance data.
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32. Shock-induced metallic iron nanoparticles in olivine-rich Martian meteorites

Author: Bruno Reynard, B. van de Moortele, Catherine McCammon, Philippe Gillet, Mike Jackson, Pierre Beck, Paul F. McMillan, Pierre Rochette, Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA), Institute for Rock Magnetism, University of Minneapolis, Department of Clinical Sciences, Unit of Tropical Laboratory Medicine, Institute of Tropical Medicine [Antwerp] (ITM), Laboratoire de Sciences de la Terre (LST), Department of Chemistry [UCL, London], University College of London [London] (UCL), Davy-Faraday Research Laboratory, Royal Institution of Great Britain, Bavarian Research Institute of Experimental Geochemistry and Geophysics (Bayerisches Geoinstitut), Universität Bayreuth, Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Collège de France (CdF)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Institut National de la Recherche Agronomique (INRA)
Subjects: 010504 meteorology & atmospheric sciences, Geochemistry, Mineralogy, [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, Mars, Chassigny, engineering.material, regolith, 010502 geochemistry & geophysics, 01 natural sciences, Crustal Magnetization, Diffusion, Paramagnetism, Shock metamorphism, [SDU.STU.PL]Sciences of the Universe [physics]/Earth Sciences/Planetology, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), shock metamorphism, Single domain, Northwest Africa 1950, olivine, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Reduction, Olivine, electron microscopy, Martian meteorites, Magnetic susceptibility, Single-Crystals, Geophysics, Meteorite, 13. Climate action, Space and Planetary Science, Remanence, [SDU]Sciences of the Universe [physics], engineering, impact, magnetic properties, Geology, Superparamagnetism, Melt
Abstract: Magnetic anomalies observed by the Mars Global Surveyor mission are attributed to crustal remanence. SNC (Shergotty-Nakhla-Chassigny) meteorites are likely samples of the Martian crust and are amenable to mineralogical and magnetic measurements essential to the understanding of the origin of magnetic anomalies. The recently discovered chassignite NWA 2737 and lherzolitic shergottite NWA 1950 display unusual magnetic characteristics that argue for a different magnetic carrier than the oxides and sulfides previously invoked in SNC meteorites. NWA 2737, the second member of the chassignite group, is a dunite with unusually dark-brown olivines and large magnetic susceptibility while Chassigny contains green olivines and is nearly a pure paramagnet. Dark olivines are also found in NWA 1950, a lherzolitic shergottite, which has singular magnetic properties when compared with other shergottites. The dark olivine color is due to the presence of Fe and FeNi metal nanoparticles, identified both by TEM and by magnetic measurements. Their size distribution encompasses the superparamagnetic to single domain transition at 30 K (10 nm range) and explains the magnetic properties of the bulk rocks. The formation of these nanoparticles is attributed to heating during the shock events that affected NWA 2737 and NWA 1950. The production of metal particles by shock-induced reduction of olivine has been invoked on surfaces deprived of atmosphere but never observed on Earth or Mars. Therefore, metal formed by shock in the heavily cratered Noachian crust is a possible carrier for crustal magnetic remanence. Widespread surface formation of metal nanoparticles could provide the precursor for the oxidized particles (goethite, hematite) observed in the Martian soils. (c) 2007 Elsevier B.V All rights reserved.
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33. Experimental studies of bond forming reactions involving molecular dications : showcase on N2++ + O2 -> NO+

Author: Odile Dutuit, Roland Thissen, Christian Alcaraz, Jan Zabka, Zdenek Herman, Francheschi, P., Soldi-Lose, H., Ricketts, Claire L., Price, Stephen D., Laboratoire de Chimie Physique D'Orsay (LCPO), Université Paris-Sud - Paris 11 (UP11)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), J. Heyrovský Institute of Physical Chemistry, J. Heyrovsky Institute of Physical Chemistry, V. Čermák Laboratory, Czech Academy of Sciences [Prague] (CAS)-J. Heyrovsky Institute of Physical Chemistry, Dipartimento di Fisica [Povo], Università degli Studi di Trento (UNITN), Institut für Chemie, Der Technischen Universität Berlin, Department of Chemistry [UCL, London], and University College of London [London] (UCL)

34. Quantum algorithms for scientific computing.

Author: Au-Yeung R, Camino B, Rathore O, and Kendon V
Abstract: Quantum computing promises to provide the next step up in computational power for diverse application areas. In this review, we examine the science behind the quantum hype, and the breakthroughs required to achieve true quantum advantage in real world applications. Areas that are likely to have the greatest impact on high performance computing (HPC) include simulation of quantum systems, optimization, and machine learning. We draw our examples from electronic structure calculations and computational fluid dynamics which account for a large fraction of current scientific and engineering use of HPC. Potential challenges include encoding and decoding classical data for quantum devices, and mismatched clock speeds between classical and quantum processors. Even a modest quantum enhancement to current classical techniques would have far-reaching impacts in areas such as weather forecasting, aerospace engineering, and the design of 'green' materials for sustainable development. This requires significant effort from the computational science, engineering and quantum computing communities working together., (Creative Commons Attribution license.)
Published: 2024
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35. Visualizing the atomic-scale origin of metallic behavior in Kondo insulators.

Author: Pirie H, Mascot E, Matt CE, Liu Y, Chen P, Hamidian MH, Saha S, Wang X, Paglione J, Luke G, Goldhaber-Gordon D, Hirjibehedin CF, Davis JCS, Morr DK, and Hoffman JE
Abstract: A Kondo lattice is often electrically insulating at low temperatures. However, several recent experiments have detected signatures of bulk metallicity within this Kondo insulating phase. In this study, we visualized the real-space charge landscape within a Kondo lattice with atomic resolution using a scanning tunneling microscope. We discovered nanometer-scale puddles of metallic conduction electrons centered around uranium-site substitutions in the heavy-fermion compound uranium ruthenium silicide (URu 2 Si 2 ) and around samarium-site defects in the topological Kondo insulator samarium hexaboride (SmB 6 ). These defects disturbed the Kondo screening cloud, leaving behind a fingerprint of the metallic parent state. Our results suggest that the three-dimensional quantum oscillations measured in SmB 6 arise from Kondo-lattice defects, although we cannot exclude other explanations. Our imaging technique could enable the development of atomic-scale charge sensors using heavy-fermion probes.
Published: 2023
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36. Design, synthesis, and evaluation of peptide-imidazo[1,2-a]pyrazine bioconjugates as potential bivalent inhibitors of the VirB11 ATPase HP0525.

Author: Sayer JR, Walldén K, Koss H, Allan H, Daviter T, Gane PJ, Waksman G, and Tabor AB
Subjects: Bacterial Proteins, Peptides pharmacology, Pyrazines, Adenosine Triphosphatases, Helicobacter pylori
Abstract: Helicobacter pylori (H. pylori) infections have been implicated in the development of gastric ulcers and various cancers: however, the success of current therapies is compromised by rising antibiotic resistance. The virulence and pathogenicity of H. pylori is mediated by the type IV secretion system (T4SS), a multiprotein macromolecular nanomachine that transfers toxic bacterial factors and plasmid DNA between bacterial cells, thus contributing to the spread of antibiotic resistance. A key component of the T4SS is the VirB11 ATPase HP0525, which is a hexameric protein assembly. We have previously reported the design and synthesis of a series of novel 8-amino imidazo[1,2-a]pyrazine derivatives as inhibitors of HP0525. In order to improve their selectivity, and potentially develop these compounds as tools for probing the assembly of the HP0525 hexamer, we have explored the design and synthesis of potential bivalent inhibitors. We used the structural details of the subunit-subunit interactions within the HP0525 hexamer to design peptide recognition moieties of the subunit interface. Different methods (cross metathesis, click chemistry, and cysteine-malemide) for bioconjugation to selected 8-amino imidazo[1,2-a]pyrazines were explored, as well as peptides spanning larger or smaller regions of the interface. The IC 50 values of the resulting linker-8-amino imidazo[1,2-a]pyrazine derivatives, and the bivalent inhibitors, were related to docking studies with the HP0525 crystal structure and to molecular dynamics simulations of the peptide recognition moieties., (© 2021 The Authors. Journal of Peptide Science published by European Peptide Society and John Wiley & Sons Ltd.)
Published: 2021
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37. Degradation of Layered Oxide Cathode in a Sodium Battery: A Detailed Investigation by X-Ray Tomography at the Nanoscale.

Author: DiLecce D, Marangon V, Isaacs M, Palgrave R, Shearing PR, and Hassoun J
Abstract: The degradation mechanism in a sodium cell of a layered Na 0.48 Al 0.03 Co 0.18 Ni 0.18 Mn 0.47 O 2 (NCAM) cathode with P3/P2 structure is investigated by revealing the changes in microstructure and composition upon cycling. The work aims to rationalize the gradual performance decay and the alteration of the electrochemical response in terms of polarization, voltage signature, and capacity loss. Spatial reconstructions of the electrode by X-ray computed tomography at the nanoscale supported by quantitative and qualitative analyses show fractures and deformations in the cycled layered metal-oxide particles, as well as inorganic side compounds deposited on the material. These irreversible morphological modifications reflect structural heterogeneities across the cathode particles due to formation of various domains with different Na + intercalation degrees. Besides, X-ray photoelectron spectroscopy data suggest that the latter inorganic species in the cycled electrode are mainly composed of NaF, Na 2 O, and NaCO 3 formed by parasitic electrolyte decomposition. The precipitation of these insulating compounds at the electrode/electrolyte interphase and the related structural stresses induced in the material lead to a decrease in cathode particle size and partial loss of electrochemical activity. The retention of the NCAM phase after cycling suggests that electrolyte upgrade may improve the performance of the cathode to achieve practical application for sustainable energy storage., (© 2021 The Authors. Small Methods published by Wiley-VCH GmbH.)
Published: 2021
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38. Rapid detection of free and bound toxins using molecularly imprinted silica/graphene oxide hybrids.

Author: Ruiz-Gonzalez A, Clancy AJ, and Choy KL
Subjects: Biosensing Techniques, Chitosan chemistry, Electrochemical Techniques, Electrodes, Humans, Limit of Detection, Molecular Imprinting, Surface Properties, Caffeine analysis, Creatinine analysis, Graphite chemistry, Indoles analysis, Nanoparticles chemistry, Renal Insufficiency, Chronic diagnosis, Silicon Dioxide chemistry
Abstract: Rapid, selective detection of biological analytes is necessary for early diagnosis, but is often complicated by the analytes being bound to proteins and the lack of fast and reliable systems available for their direct assessment. Here, a cheap, easily-assembled molecularly imprinted silica/graphene oxide hybrid is developed, which can selectively detect toxins linked to early-stage chronic kidney disease, down to femtomolar concentrations within 5 minutes. The hybrid material is capable of simultaneously and separately measuring free and bound analytes using with an ultra-low limit of detection in the femtomolar range, and uses processes intrinsically adaptable to any charged molecular analyte.
Published: 2021
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39. Advances in applied supramolecular technologies.

Author: Williams GT, Haynes CJE, Fares M, Caltagirone C, Hiscock JR, and Gale PA
Abstract: Supramolecular chemistry is a comparatively young field that to date has mainly been focused on building a foundation of fundamental understanding. With much progress in this area, researchers are seeking to apply this knowledge to the development of commercially viable products. In this review we seek to outline historical and recent developments within the field of supramolecular chemistry that have made the transition from laboratory to market, and to bring to light those technologies that we believe have commercial potential. In doing so we hope we may illuminate pathways to market for research currently being conducted.
Published: 2021
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40. Post-epizootic microbiome associations across communities of neotropical amphibians.

Author: Jervis P, Pintanel P, Hopkins K, Wierzbicki C, Shelton JMG, Skelly E, Rosa GM, Almeida-Reinoso D, Eugenia-Ordoñez M, Ron S, Harrison X, Merino-Viteri A, and Fisher MC
Subjects: Amphibians, Animals, Ecuador, Chytridiomycota genetics, Microbiota genetics, Mycoses veterinary
Abstract: Microbiome-pathogen interactions are increasingly recognized as an important element of host immunity. While these host-level interactions will have consequences for community disease dynamics, the factors which influence host microbiomes at larger scales are poorly understood. We here describe landscape-scale pathogen-microbiome associations within the context of post-epizootic amphibian chytridiomycosis, a disease caused by the panzootic chytrid fungus Batrachochytrium dendrobatidis. We undertook a survey of Neotropical amphibians across altitudinal gradients in Ecuador ~30 years following the observed amphibian declines and collected skin swab-samples which were metabarcoded using both fungal (ITS-2) and bacterial (r16S) amplicons. The data revealed marked variation in patterns of both B. dendrobatidis infection and microbiome structure that are associated with host life history. Stream breeding amphibians were most likely to be infected with B. dendrobatidis. This increased probability of infection was further associated with increased abundance and diversity of non-Batrachochytrium chytrid fungi in the skin and environmental microbiome. We also show that increased alpha diversity and the relative abundance of fungi are lower in the skin microbiome of adult stream amphibians compared to adult pond-breeding amphibians, an association not seen for bacteria. Finally, stream tadpoles exhibit lower proportions of predicted protective microbial taxa than pond tadpoles, suggesting reduced biotic resistance. Our analyses show that host breeding ecology strongly shapes pathogen-microbiome associations at a landscape scale, a trait that may influence resilience in the face of emerging infectious diseases., (© 2021 The Authors. Molecular Ecology published by John Wiley & Sons Ltd.)
Published: 2021
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41. A Chemical Biology Approach to Probing the Folding Pathways of the Inhibitory Cystine Knot (ICK) Peptide ProTx-II.

Author: McCarthy S, Robinson J, Thalassinos K, and Tabor AB
Abstract: Peptide toxins that adopt the inhibitory cystine knot (ICK) scaffold have very stable three-dimensional structures as a result of the conformational constraints imposed by the configuration of the three disulfide bonds that are the hallmark of this fold. Understanding the oxidative folding pathways of these complex peptides, many of which are important therapeutic leads, is important in order to devise reliable synthetic routes to correctly folded, biologically active peptides. Previous research on the ICK peptide ProTx-II has shown that in the absence of an equilibrating redox buffer, misfolded intermediates form that prevent the formation of the native disulfide bond configuration. In this paper, we used tandem mass spectrometry to examine these misfolded peptides, and identified two non-native singly bridged peptides, one with a Cys(III)-Cys(IV) linkage and one with a Cys(V)-Cys(VI) linkage. Based on these results, we propose that the C -terminus of ProTx-II has an important role in initiating the folding of this peptide. To test this hypothesis, we have also studied the folding pathways of analogs of ProTx-II containing the disulfide-bond directing group penicillamine (Pen) under the same conditions. We find that placing Pen residues at the C -terminus of the ProTx-II analogs directs the folding pathway away from the singly bridged misfolded intermediates that represent a kinetic trap for the native sequence, and allows a fully oxidized final product to be formed with three disulfide bridges. However, multiple two-disulfide peptides were also produced, indicating that further study is required to fully control the folding pathways of this modified scaffold., (Copyright © 2020 McCarthy, Robinson, Thalassinos and Tabor.)
Published: 2020
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42. Electric polarization switching in an atomically thin binary rock salt structure.

Author: Martinez-Castro J, Piantek M, Schubert S, Persson M, Serrate D, and Hirjibehedin CF
Abstract: Inducing and controlling electric dipoles is hindered in the ultrathin limit by the finite screening length of surface charges at metal-insulator junctions 1-3 , although this effect can be circumvented by specially designed interfaces 4 . Heterostructures of insulating materials hold great promise, as confirmed by perovskite oxide superlattices with compositional substitution to artificially break the structural inversion symmetry 5-8 . Bringing this concept to the ultrathin limit would substantially broaden the range of materials and functionalities that could be exploited in novel nanoscale device designs. Here, we report that non-zero electric polarization can be induced and reversed in a hysteretic manner in bilayers made of ultrathin insulators whose electric polarization cannot be switched individually. In particular, we explore the interface between ionic rock salt alkali halides such as NaCl or KBr and polar insulating Cu 2 N terminating bulk copper. The strong compositional asymmetry between the polar Cu 2 N and the vacuum gap breaks inversion symmetry in the alkali halide layer, inducing out-of-plane dipoles that are stabilized in one orientation (self-poling). The dipole orientation can be reversed by a critical electric field, producing sharp switching of the tunnel current passing through the junction.
Published: 2018
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43. Guided Molecular Assembly on a Locally Reactive 2D Material.

Author: Warner B, Gill TG, Caciuc V, Atodiresei N, Fleurence A, Yoshida Y, Hasegawa Y, Blügel S, Yamada-Takamura Y, and Hirjibehedin CF
Abstract: Atomically precise engineering of the position of molecular adsorbates on surfaces of 2D materials is key to their development in applications ranging from catalysis to single-molecule spintronics. Here, stable room-temperature templating of individual molecules with localized electronic states on the surface of a locally reactive 2D material, silicene grown on ZrB 2 , is demonstrated. Using a combination of scanning tunneling microscopy and density functional theory, it is shown that the binding of iron phthalocyanine (FePc) molecules is mediated via the strong chemisorption of the central Fe atom to the sp 3 -like dangling bond of Si atoms in the linear silicene domain boundaries. Since the planar Pc ligand couples to the Fe atom mostly through the in-plane d orbitals, localized electronic states resembling those of the free molecule can be resolved. Furthermore, rotation of the molecule is restrained because of charge rearrangement induced by the bonding. These results highlight how nanoscale changes can induce reactivity in 2D materials, which can provide unique surface interactions for enabling novel forms of guided molecular assembly., (© 2017 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
Published: 2017
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44. Gating Classical Information Flow via Equilibrium Quantum Phase Transitions.

Author: Banchi L, Fernández-Rossier J, Hirjibehedin CF, and Bose S
Abstract: The development of communication channels at the ultimate size limit of atomic scale physical dimensions will make the use of quantum entities an imperative. In this regime, quantum fluctuations naturally become prominent and are generally considered to be detrimental. Here, we show that for spin-based information processing, these fluctuations can be uniquely exploited to gate the flow of classical binary information across a magnetic chain in thermal equilibrium. Moreover, this information flow can be controlled with a modest external magnetic field that drives the system through different many-body quantum phases in which the orientation of the final spin does or does not reflect the orientation of the initial input. Our results are general for a wide class of anisotropic spin chains that act as magnetic cellular automata and suggest that quantum phase transitions play a unique role in driving classical information flow at the atomic scale.
Published: 2017
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45. Controlling electronic access to the spin excitations of a single molecule in a tunnel junction.

Author: Warner B, El Hallak F, Prüser H, Ajibade A, Gill TG, Fisher AJ, Persson M, and Hirjibehedin CF
Abstract: Spintronic phenomena underpin new device paradigms for data storage and sensing. Scaling these down to the single molecule level requires controlling the properties of current-carrying molecular orbitals to enable access to spin states through phenomena such as inelastic electron tunnelling. Here we show that the spintronic properties of a tunnel junction containing a single molecule can be controlled using the local environment as a pseudo-gate. For tunnelling through iron phthalocyanine (FePc) on an insulating copper nitride (Cu 2 N) monolayer above Cu(001), we find that spin transitions may be strongly excited depending on the binding site of the central Fe atom. Different interactions between the Fe and the underlying Cu or N atoms shift the Fe d orbitals with respect to the Fermi energy and control the relative strength of the spin excitations; this effect is captured in a simple co-tunnelling model. This work demonstrates the importance of the atomic-scale environment for the development of single molecule spintronic devices.
Published: 2017
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46. Tunable magnetoresistance in an asymmetrically coupled single-molecule junction.

Author: Warner B, El Hallak F, Prüser H, Sharp J, Persson M, Fisher AJ, and Hirjibehedin CF
Abstract: Phenomena that are highly sensitive to magnetic fields can be exploited in sensors and non-volatile memories. The scaling of such phenomena down to the single-molecule level may enable novel spintronic devices. Here, we report magnetoresistance in a single-molecule junction arising from negative differential resistance that shifts in a magnetic field at a rate two orders of magnitude larger than Zeeman shifts. This sensitivity to the magnetic field produces two voltage-tunable forms of magnetoresistance, which can be selected via the applied bias. The negative differential resistance is caused by transient charging of an iron phthalocyanine (FePc) molecule on a single layer of copper nitride (Cu2N) on a Cu(001) surface, and occurs at voltages corresponding to the alignment of sharp resonances in the filled and empty molecular states with the Cu(001) Fermi energy. An asymmetric voltage-divider effect enhances the apparent voltage shift of the negative differential resistance with magnetic field, which inherently is on the scale of the Zeeman energy. These results illustrate the impact that asymmetric coupling to metallic electrodes can have on transport through molecules, and highlight how this coupling can be used to develop molecular spintronic applications.
Published: 2015
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47. Quantized water access to the HIV-1 protease active site as a proposed mechanism for cooperative mutations in drug affinity.

Author: Hall BA, Wright DW, Jha S, and Coveney PV
Subjects: Drug Resistance, Viral genetics, HIV Protease genetics, Mutation, Thermodynamics, Catalytic Domain genetics, HIV Protease chemistry, HIV Protease Inhibitors chemistry, Lopinavir pharmacology, Ritonavir pharmacology, Water pharmacology
Abstract: The development of resistance to different drugs remains a major problem for a wide range of infections. In particular, combinations of specific mutations, which individually demonstrate no effect, exhibit significant cooperativity. Here we show that changes to the energy of ligand binding in different resistant HIV-1 proteases are correlated with the creation of water binding sites in the active site. This correlation is conserved across two drugs (ritonavir and lopinavir). We propose that individual mutations induce changes in flap packing that are insufficient to allow water binding but in combination allow access, leading to the observed cooperative resistance.
Published: 2012
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