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116 results on '"Laurent Wiesenfeld"'

1. Charge transfer of polyatomic molecules in ion-atom hybrid traps: Stereodynamics in the millikelvin regime

Author: Alexandre Voute, Alexander Dörfler, Laurent Wiesenfeld, Olivier Dulieu, Fabien Gatti, Daniel Peláez, and Stefan Willitsch
Subjects: Physics, QC1-999
Abstract: Rate constants for the charge-transfer reaction between N_{2}H^{+} and Rb in the millikelvin regime are measured in an ion-atom hybrid trap and are found to be lower than the Langevin capture limit. Multireference ab initio computation of the potential energy surfaces involved in the reaction reveals that the low-temperature charge transfer is hindered by short-range features highly dependent on the collision angle and is promoted by a deformation of the molecular frame. The present study highlights the importance of polyatomic effects and of stereodynamics in cold molecular ion-neutral collisions.
Published: 2023
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2. Near-Threshold and Resonance Effects in Rotationally Inelastic Scattering of D2O with Normal-H2

Author: Astrid Bergeat, Alexandre Faure, Laurent Wiesenfeld, Chloé Miossec, Sébastien B. Morales, and Christian Naulin
Subjects: inelastic collisions, cross-sections, water, hydrogen, Organic chemistry, QD241-441
Abstract: We present a combined experimental and theoretical study on the rotationally inelastic scattering of heavy water, D2O, with normal-H2. Crossed-molecular beam measurements are performed in the collision energy range between 10 and 100 cm−1, corresponding to the near-threshold regime in which scattering resonances are most pronounced. State-to-state excitation cross-sections are obtained by probing three low-lying rotational levels of D2O using the REMPI technique. These measurements are complemented by quantum close-coupling scattering calculations based on a high-accuracy D2O–H2 interaction potential. The agreement between experiment and theory is within the experimental error bars at 95% confidence intervals, leading to a relative difference of less than 7%: the near-threshold rise and the overall shape of the cross-sections, including small undulations due to resonances, are nicely reproduced by the calculations. Isotopic effects (D2O versus H2O) are also discussed by comparing the shape and magnitude of the respective cross-sections.
Published: 2022
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3. A Molecular Candle Where Few Molecules Shine: HeHHe+

Author: Ryan C. Fortenberry and Laurent Wiesenfeld
Subjects: helium chemistry, infrared spectroscopy, early universe, quantum chemistry, Organic chemistry, QD241-441
Abstract: HeHHe + is the only potential molecule comprised of atoms present in the early universe that is also easily observable in the infrared. This molecule has been known to exist in mass spectrometry experiments for nearly half-a-century and is likely present, but as-of-yet unconfirmed, in cold plasmas. There can exist only a handful of plausible primordial molecules in the epochs before metals (elements with nuclei heavier than 4 He as astronomers call them) were synthesized in the universe, and most of these are both rotationally and vibrationally dark. The current work brings HeHHe + into the discussion as a possible (and potentially only) molecular candle for probing high-z and any metal-deprived regions due to its exceptionally bright infrared feature previously predicted to lie at 7.43 μ m. Furthermore, the present study provides new insights into its possible formation mechanisms as well as marked stability, along with the decisive role of anharmonic zero-point energies. A new entrance pathway is proposed through the triplet state ( 3 B 1 ) of the He 2 H + molecule complexed with a hydrogen atom and a subsequent 10.90 eV charge transfer/photon emission into the linear and vibrationally-bright 1 Σ g + HeHHe + form.
Published: 2020
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4. Quenching transitions for the rovibrational transitions of water: Ortho-H

Author: Laurent, Wiesenfeld
Abstract: We present here the first full computation of the rovibrational quenching of a polyatomic molecule (water) by a rotating molecular projectile (H
Published: 2022

5. Rotational (de)-excitation of cyclic and linear C3H2 by collision with He

Author: Olivier Dulieu, S. Spezzano, Kamel Hammami, M. Ben Khalifa, Laurent Wiesenfeld, Paola Caselli, F. Khadri, Emna Sahnoun, Laboratoire de Spectroscopie Atomique, Moléculaire et Applications (LSAMA), Université de Tunis El Manar (UTM)-Faculté des Sciences Mathématiques, Physiques et Naturelles de Tunis (FST), Université de Tunis El Manar (UTM), Laboratoire Aimé Cotton (LAC), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-École normale supérieure - Cachan (ENS Cachan), Max Planck Institute for Extraterrestrial Physics (MPE), Max-Planck-Gesellschaft, and Max-Planck-Institut für Extraterrestrische Physik (MPE)
Subjects: Cyclopropenylidene, Angular momentum, General Physics and Astronomy, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, 7. Clean energy, chemistry.chemical_compound, Physical and Theoretical Chemistry, Collisional excitation, ComputingMilieux_MISCELLANEOUS, Astrophysics::Galaxy Astrophysics, Physics, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], Spherical harmonics, 021001 nanoscience & nanotechnology, 0104 chemical sciences, 3. Good health, Computational physics, Electric dipole moment, chemistry, [SDU]Sciences of the Universe [physics], Potential energy surface, [SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], Rotational spectroscopy, 0210 nano-technology, Excitation
Abstract: Among the closed-shell hydrocarbons, the carbenes c- and l-C3H2 are the lightest ones to display a permanent electric dipole moment and be detectable by rotational spectroscopy. The cyclic form, cyclopropenylidene, is ubiquitous in the InterStellar Matter (ISM) of the Milky Way and external galaxies. As such, it serves as a marker to help in characterizing the physical conditions of the ISM. The linear form, propadienylidene, is less abundant. In order to get access to their absolute and relative abundances, it is essential to understand their collisional excitation/quenching schemes. We compute here a precise ab initio potential energy surface for the interaction of c- and l-C3H2 with helium, by means of a CCSD(T)-F12a formalism and a fit onto relevant spherical harmonics functions. We conduct quantum dynamical scattering in order to get precise cross sections using a coupled-channel approach for solving the nuclear motion. We average sections to have rates for rotational quenching from 5 to 150 K. We show that these new rates are vastly different, up to more than an order of magnitude, from the older rates presented in the literature, computed with angular momentum algebra only. We expect large differences in the astrophysical analyses of C3H2, including the chemical history of those ubiquitous carbenes.
Published: 2019
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6. Rotational (de)-excitation of HMgNC in collision with He

Author: Kamel Hammami, Laurent Wiesenfeld, M. A. Amor, Laboratoire Aimé Cotton (LAC), and CNRS-Université de Paris-Sud
Subjects: Physics, Scattering, Astronomy and Astrophysics, 010402 general chemistry, Collision, 01 natural sciences, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, [PHYS.ASTR.GA]Physics [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], Space and Planetary Science, 0103 physical sciences, Physics::Atomic and Molecular Clusters, Radiative transfer, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], Physics::Chemical Physics, Atomic physics, 010303 astronomy & astrophysics, Excitation
Abstract: Potential energy surface for the collision between HMgNC and He are evaluated using the high-accuracy CCSD(T)-F12 ab-initio method. This PES leads to conduct quantum dynamical scattering calculations of the rotational and hyperfine (de)-excitations rate coefficients for temperatures up to 200 K. In order to evaluate the impact of the computed data, we performed radiative transfer computations of the brightness and excitation temperatures for selected observed j = 8 to 7 transition.
Published: 2021
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7. Probing Low-Energy Resonances in Water-Hydrogen Inelastic Collisions

Author: Christian Naulin, Laurent Wiesenfeld, Alexandre Faure, Sébastien B. Morales, Astrid Bergeat, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), 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)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-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)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Laboratoire Aimé Cotton (LAC), and CNRS-Université de Paris-Sud
Subjects: Physics, [PHYS]Physics [physics], Hydrogen, Scattering, Inelastic collision, General Physics and Astronomy, Resonance, Order (ring theory), chemistry.chemical_element, Inelastic scattering, Kinetic energy, 01 natural sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, [PHYS.ASTR.GA]Physics [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], chemistry, 0103 physical sciences, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], Atomic physics, 010306 general physics, Energy (signal processing), ComputingMilieux_MISCELLANEOUS
Abstract: Molecular scattering at collisional energies of the order of $10--100\text{ }\text{ }\mathrm{c}{\mathrm{m}}^{\ensuremath{-}1}$ (corresponding to kinetic temperatures in the 15--150 K range) provides insight into the details of the scattering process and, in particular, of the various resonances that appear in inelastic cross sections. In this Letter, we present a detailed experimental and theoretical study of the rotationally inelastic scattering of ground-state ortho-${\mathrm{D}}_{2}\mathrm{O}$ by ground-state para-${\mathrm{H}}_{2}$ in the threshold region of the ${\mathrm{D}}_{2}\mathrm{O}({0}_{00}\ensuremath{\rightarrow}{2}_{02})$ transition at $35.9\text{ }\text{ }\mathrm{c}{\mathrm{m}}^{\ensuremath{-}1}$. The measurements were performed with a molecular crossed beam apparatus with variable collision angle, thence with variable collisional energy. Calculations were carried out with the coupled-channel method combined with a dedicated high-level ${\mathrm{D}}_{2}\mathrm{O}\text{\ensuremath{-}}{\mathrm{H}}_{2}$ intermolecular potential. Our theoretical cross section ${0}_{00}\ensuremath{\rightarrow}{2}_{02}$ is found to display several resonance peaks in perfect agreement with the experimental work, in their absolute positions and relative intensities. We show that those peaks are mostly due to shape resonances, characterized here for the first time for a polyatomic molecule colliding with a diatom.
Published: 2020
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8. Potential Energy Surface for the CH 4 –H 2 van der Waals Interaction

Author: Laurent Wiesenfeld, Emna Sahnoun, Kamel Hammami, Laboratoire Aimé Cotton (LAC), CNRS-Université de Paris-Sud, and Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-École normale supérieure - Cachan (ENS Cachan)
Subjects: 010402 general chemistry, 01 natural sciences, Methane, chemistry.chemical_compound, symbols.namesake, Planet, 0103 physical sciences, Mathematics::Metric Geometry, Molecule, Physics::Chemical Physics, Physical and Theoretical Chemistry, ComputingMilieux_MISCELLANEOUS, 010304 chemical physics, Component (thermodynamics), 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, [PHYS.ASTR.GA]Physics [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], chemistry, 13. Climate action, Chemical physics, Potential energy surface, symbols, Astrophysics::Earth and Planetary Astrophysics, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], van der Waals force, Earth (classical element)
Abstract: Methane is an ubiquitous molecule, present as a minor component in many environments, including the Earth and planet atmospheres. Its van der Waals interaction with the main gases is an important i...
Published: 2020
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9. Potential Energy Surface for the CH

Author: Emna, Sahnoun, Laurent, Wiesenfeld, and Kamel, Hammami
Abstract: Methane is an ubiquitous molecule, present as a minor component in many environments, including the Earth and planet atmospheres. Its van der Waals interaction with the main gases is an important ingredient for the understanding of radiative properties for those atmospheres. We present here the first precise determination of the interaction between CH
Published: 2020

10. Quenching of interstellar carbenes: Interaction of C 3 H 2 with He and H 2

Author: Olivier Dulieu, Kamel Hammami, Laurent Wiesenfeld, M. Ben Khalifa, Emna Sahnoun, F. Khadri, Laboratoire Aimé Cotton (LAC), and CNRS-Université de Paris-Sud
Subjects: History, Materials science, Quenching (fluorescence), 02 engineering and technology, 010402 general chemistry, 021001 nanoscience & nanotechnology, Photochemistry, 01 natural sciences, 0104 chemical sciences, Computer Science Applications, Education, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, [PHYS.ASTR.GA]Physics [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], 13. Climate action, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], 0210 nano-technology, ComputingMilieux_MISCELLANEOUS
Abstract: Synopsis C3H2 molecules are ubiquitous in the Galaxy and present important challenges in their chemistry, whether cyclic or linear, and possibly substituted with D. Obtaining theoretical rotational quenching rates by collisions with He and H2 as projectiles is of great importance in order to get quantitative abundance estimates. It is all the more challenging that many rotational lines are excited during the collision, resulting in computationnally very heavy quantum dynamics. The quality of various approximations will be discussed, as well as the quenching rates for astrophysical applications.
Published: 2020
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11. Rotationally inelastic collisions of SiO with H2

Author: Christian Balança, Fabrice Dayou, Nicole Feautrier, Laurent Wiesenfeld, Alexandre Faure, 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), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), and 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 Grenoble Alpes [2016-2019] (UGA [2016-2019])-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 Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])
Subjects: [PHYS]Physics [physics], Physics, Nuclear physics, 010304 chemical physics, Space and Planetary Science, Scattering, 0103 physical sciences, Inelastic collision, Astronomy and Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, 01 natural sciences, ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2018
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12. Quenching rates and critical densities of c -C 3 H 2

Author: S. Spezzano, Kamel Hammami, Laurent Wiesenfeld, Paola Caselli, Malek Ben Khalifa, Olivier Dulieu, Emna Sahnoun, Laboratoire Aimé Cotton (LAC), and CNRS-Université de Paris-Sud
Subjects: Quenching (fluorescence), Astrochemistry, Materials science, Astronomy and Astrophysics, 02 engineering and technology, 021001 nanoscience & nanotechnology, Photochemistry, 7. Clean energy, 01 natural sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, [PHYS.ASTR.GA]Physics [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], 13. Climate action, Space and Planetary Science, 0103 physical sciences, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], 0210 nano-technology, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS
Abstract: Cyclopropenylidene,, is a simple hydrocarbon, ubiquitous in astrophysical gases, and possessing a permanent electric dipole moment. Its readily observed multifrequency rotational transitions make it an excellent probe for the physics and history of interstellar matter. The collisional properties of with He are presented here. We computed the full Potential Energy Surfaces, and we perform quantum scattering in order to provide rates of quenching and excitation for low to medium temperature regimes. We discuss issues with the validity of the usual Local Thermodynamical Equilibrium assumption, and also the intricacies of the spectroscopy of an asymmetric top. We present the wide range of actual critical densities, as recently observed.
Published: 2019
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13. Modelling the abundance structure of isocyanic acid (HNCO) towards the low-mass solar type protostar IRAS 16293–2422

Author: Emna Sahnoun, Antonio Hernández-Gómez, Karl M. Menten, Kamel Hammami, Laurent Wiesenfeld, Laurent Loinard, Emmanuel Caux, Sandrine Bottinelli, Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-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)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Centre d'étude spatiale des rayonnements (CESR), 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)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Centro de Radioastronomia y Astrofisica (CRyA), Universidad Nacional Autónoma de México (UNAM), Millimeter and Submillimeter Astronomy, Max-Planck-Institut für Radioastronomie (MPIFR), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), and Universidad Nacional Autónoma de México = National Autonomous University of Mexico (UNAM)
Subjects: Astrochemistry, FOS: Physical sciences, Astrophysics, 7. Clean energy, 01 natural sciences, Spectral line, chemistry.chemical_compound, 0103 physical sciences, Radiative transfer, Protostar, Astrophysics::Solar and Stellar Astrophysics, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, Line (formation), Physics, 010308 nuclear & particles physics, astrochemistry, Molecular cloud, stars: individual (IRAS 16293-2422), Astronomy and Astrophysics, Isocyanic acid, Astrophysics - Astrophysics of Galaxies, Galaxy, ISM: molecules, Astrophysics - Solar and Stellar Astrophysics, chemistry, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), Astrophysics::Earth and Planetary Astrophysics, [SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA]
Abstract: International audience; Isocyanic acid (HNCO), the most stable of the simplest molecules containing the four main elements essential for organic chemistry, has been observed in several astrophysical environments such as molecular clouds, star-forming regions, external galaxies, and comets. In this work, we model HNCO spectral line profiles towards the low-mass solar type protostar IRAS 16293-2422 observed with the ALMA interferometer, the IRAM, JCMT, and APEX single-dish radio telescopes, and the HIFI instrument on board the Herschel Space Observatory. In star-forming environments, the HNCO emission is not always in Local Thermodynamical Equilibrium (LTE). A non-LTE radiative transfer approach is necessary to properly interpret the line profiles, and accurate collisional rate coefficients are needed. Here, we used the RADEX package with a completely new set of collisional quenching rates between HNCO and both ortho-H2 and para-H2 obtained from quantum chemical calculations yielding a novel potential energy surface in the rigid rotor approximation. We find that the lines profiles towards IRAS 16293-2422 are very well reproduced if we assume that the HNCO emission arises from a compact, dense, and hot physical component associated with the hot corino, a warm component associated with the internal part of the protostellar envelope, and a cold and more extended component associated with the outer envelope. The derived HNCO abundances from our model agree well with those computed with the NAUTILUS chemical code.
Published: 2019
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14. The Dense Gas Fraction in Galactic Center Clouds

Author: Laurent Wiesenfeld, K. Immer, Elisabeth A. C. Mills, Mark Morris, Adam Ginsburg, Jonathan Barnes, M. A. Requena-Torres, Alexandre Faure, European Southern Observatory (ESO), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), and 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 Grenoble Alpes [2016-2019] (UGA [2016-2019])-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 Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])
Subjects: Physics, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010308 nuclear & particles physics, Star formation, Milky Way, Galactic Center, FOS: Physical sciences, Astronomy and Astrophysics, Radius, Astrophysics, 01 natural sciences, Astrophysics - Astrophysics of Galaxies, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, Disc, 010303 astronomy & astrophysics, Mass fraction, Excitation, ComputingMilieux_MISCELLANEOUS, Line (formation)
Abstract: We present an analysis of gas densities in the central R=300 parsecs of the Milky Way, focusing on three clouds: GCM-0.02-0.07 (the 50 km/s cloud), GCM-0.13-0.08 (the 20 km/s cloud), and GCM0.25+0.01 (the "Brick"). Densities are determined using observations of the J=(3-2), (4-3), (5-4), (10-9), (18-17), (19-18), (21-20), and (24-23) transitions of the molecule HC3N. We find evidence of at least two excitation regimes for HC3N and constrain the low-excitation component to have a density less than 10^4 cm^-3 and the high-excitation component to have a density between 10^5 and 10^6 cm^-3. This is much less than densities of 10^7 cm^-3 that are found in Sgr B2, the most actively star-forming cloud in the Galactic center. This is consistent with the requirement of a higher density threshold for star formation in the Galactic center than is typical in the Galactic disk. We are also able to constrain the column density of each component in order to determine the mass fraction of 'dense' (n>10^5 cm^-3) gas for these clouds. We find that this is ~15% for all three clouds. Applying the results of our models to ratios of the (10-9) and (3-2) line across the entire central R=300 pc, we find that the fraction of gas with n>10^4 cm^-3 increases inward of a radius of ~140 pc, consistent with the predictions of recent models for the gas dynamics in this region. Our observations show that HC3N is an excellent molecule for probing the density structure of clouds in the Galactic center., 20 pages, 8 figures, 3 tables. ApJ accepted
Published: 2018
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15. van der Waals interaction of HNCO and H

Author: Emna, Sahnoun, Laurent, Wiesenfeld, Kamel, Hammami, and Nejmeddine, Jaidane
Abstract: Isocyanic acid (HNCO) is the most stable of all its isomers; it has been observed repeatedly in many different conditions of the Interstellar Media, and its chemistry is poorly known. To quantitatively estimate the abundance of HNCO with respect to other organic molecules, we compute its rotational quenching rates colliding with H
Published: 2018

16. van der Waals interaction of HNCO and H 2 : Potential Energy Surface and Rotational Energy Transfer

Author: Kamel Hammami, Laurent Wiesenfeld, Emna Sahnoun, Nejm-Eddine Jaidane, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), and 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 Grenoble Alpes [2016-2019] (UGA [2016-2019])-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 Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])
Subjects: 010304 chemical physics, Mean kinetic temperature, Chemistry, Ab initio, Inelastic scattering, Isocyanic acid, 7. Clean energy, 01 natural sciences, Molecular physics, Rotational energy, symbols.namesake, chemistry.chemical_compound, 13. Climate action, 0103 physical sciences, Potential energy surface, symbols, Molecule, [SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], Physical and Theoretical Chemistry, van der Waals force, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, ComputingMilieux_MISCELLANEOUS
Abstract: Isocyanic acid (HNCO) is the most stable of all its isomers; it has been observed repeatedly in many different conditions of the Interstellar Media, and its chemistry is poorly known. To quantitatively estimate the abundance of HNCO with respect to other organic molecules, we compute its rotational quenching rates colliding with H2, the most common gas in the gaseous Interstellar Media. We compute ab initio the van der Waals interaction HNCO–H2, in the rigid molecules approximation, with a CCSD(T)-F12a method. On the fitted ab initio surface, inelastic scattering cross sections and rates are calculated for a temperature range of 7–200 K, with the coupled-states quantum time-independent formalism. The critical densities are high enough to yield rotational temperatures of HNCO differing significantly from the kinetic temperature of H2, especially so for the shorter wavelengths observed at the ALMA interferometer. It is found that the quenching rates for collisions with ortho- or para-H2 differ greatly, open...
Published: 2018
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17. Collisional excitation of NH3 by atomic and molecular hydrogen

Author: F. Daniel, N. Bouhafs, F. Dumouchel, François Lique, Laurent Wiesenfeld, Alexandre Faure, Claire Rist, Laboratoire Ondes et Milieux Complexes (LOMC), Centre National de la Recherche Scientifique (CNRS)-Université Le Havre Normandie (ULH), Normandie Université (NU)-Normandie Université (NU), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), 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 Grenoble Alpes [2016-2019] (UGA [2016-2019])-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 Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), 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), Ctr Astrobiol CSIC INTA, Lab Astrofis Mol, Madrid 28850, Spain, Ctr Astrobiol CSIC INTA, Lab Astrofis Mol, Madrid, Université Le Havre Normandie (ULH), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Neurobiologie de l'apprentissage, de la mémoire et de la communication (NAMC), and Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, Chemical Physics (physics.chem-ph), [PHYS]Physics [physics], Range (particle radiation), 010304 chemical physics, Projectile, Calibration curve, FOS: Physical sciences, Astronomy and Astrophysics, Kinetic energy, 01 natural sciences, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Thermometer, Physics - Chemical Physics, 0103 physical sciences, Calibration, Atomic physics, 010303 astronomy & astrophysics, Collisional excitation, Excitation, Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics::Galaxy Astrophysics, ComputingMilieux_MISCELLANEOUS
Abstract: We report extensive theoretical calculations on the rotation-inversion excitation of interstellar ammonia (NH3) due to collisions with atomic and molecular hydrogen (both para- and ortho-H2). Close-coupling calculations are performed for total energies in the range 1-2000 cm-1 and rotational cross sections are obtained for all transitions among the lowest 17 and 34 rotation-inversion levels of ortho- and para-NH3, respectively. Rate coefficients are deduced for kinetic temperatures up to 200 K. Propensity rules for the three colliding partners are discussed and we also compare the new results to previous calculations for the spherically symmetrical He and para-H2 projectiles. Significant differences are found between the different sets of calculations. Finally, we test the impact of the new rate coefficients on the calibration of the ammonia thermometer. We find that the calibration curve is only weakly sensitive to the colliding partner and we confirm that the ammonia thermometer is robust.
Published: 2017
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18. Collision energy dependence of state-to-state differential cross sections for rotationally inelastic scattering of H

Author: Gautam, Sarma, Ashim Kumar, Saha, Chandan Kumar, Bishwakarma, Roy, Scheidsbach, Chung-Hsin, Yang, David, Parker, Laurent, Wiesenfeld, Udo, Buck, Lazaros, Mavridis, and Sarantos, Marinakis
Abstract: The inelastic scattering of H
Published: 2017

19. Seeds of Life in Space (SOLIS): I. Carbon-chain growth in the Solar-type protocluster OMC2-FIR4

Author: Rafael Bachiller, S. Spezzano, Jaime E. Pineda, Emmanuel Caux, Paola Caselli, Bertrand Lefloch, Piero Ugliengo, Yoko Oya, Audrey Coutens, Claudio Codella, Serena Viti, Claudine Kahane, Andy Pon, Jonathan Holdship, R. Neri, R. Choudhury, P. Hily-Blant, Patrice Theulé, Jacob C. Laas, Anton Vasyunin, Sandrine Bottinelli, A. Jaber Al-Edhari, Francesco Fontani, Izaskun Jiménez-Serra, Linda Podio, Felipe O. Alves, François Dulieu, Laurent Wiesenfeld, Cecilia Ceccarelli, D. Quénard, Satoshi Yamamoto, Cécile Favre, Ian R. Sims, Leonardo Testi, Vianney Taquet, Luca Bizzocchi, Nami Sakai, Ana López-Sepulcre, Albert Rimola, Nadia Balucani, E. Bianchi, Ana Chacón-Tanarro, Anna Punanova, Siyi Feng, C. Vastel, INAF - Osservatorio Astronomico di Brera (OAB), Istituto Nazionale di Astrofisica (INAF), 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), Max Planck Institute for Extraterrestrial Physics (MPE), Max-Planck-Gesellschaft, 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), Università degli Studi di Perugia (UNIPG), Università degli Studi di Firenze [Firenze], 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), INAF - Osservatorio Astrofisico di Arcetri (OAA), University College of London [London] (UCL), 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), Universitat Autònoma de Barcelona [Barcelona] (UAB), Queen Mary University of London (QMUL), University of Western Ontario (UWO), RIKEN - Institute of Physical and Chemical Research [Japon] (RIKEN), Universiteit Leiden [Leiden], Physique des interactions ioniques et moléculaires (PIIM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Università degli studi di Torino (UNITO), Ural Federal University [Ekaterinburg] (UrFU), University of Electro-Communications [Tokyo] (UEC), Physique et Chimie du Milieu Interstellaire (PCMI) - Conseil National de la Recherche Scientifique (CNRS), Centre National d'Etudes Spatiales (CNES), LabeX Osug (Investissements d'avenir) [ANR10LABX56], Canadian Institute for Theoretical Astrophysics (CITA), European Research Council [PALs 320620], Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), 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 Grenoble Alpes [2016-2019] (UGA [2016-2019])-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 Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Università degli Studi di Firenze = University of Florence [Firenze] (UNIFI), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), 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)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), 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), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Universitat Autònoma de Barcelona (UAB), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), Università degli Studi di Perugia = University of Perugia (UNIPG), Università degli Studi di Firenze = University of Florence (UniFI), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), 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 de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris-Seine-Université Paris-Seine-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Universiteit Leiden, and Università degli studi di Torino = University of Turin (UNITO)
Subjects: 010504 meteorology & atmospheric sciences, radio lines ISM, CHEMICAL MODEL, chemistry.chemical_element, Flux, Astrophysics, 01 natural sciences, 7. Clean energy, star formation, MOLECULES, ISM molecules, ABUNDANCE RATIOS, FORMATION [STARS], 0103 physical sciences, Cluster (physics), CHAINS, 010303 astronomy & astrophysics, INTERSTELLAR MEDIUMS, ComputingMilieux_MISCELLANEOUS, Radio lines: ISM, 0105 earth and related environmental sciences, Line (formation), Physics, [PHYS]Physics [physics], EASTERN REGIONS, ISM: Molecules, Stars: Formation, Astronomy and Astrophysics, Space and Planetary Science, IONISATION RATES, Star formation, ISM [RADIO LINES], COSMIC RAYS, Galaxy, Interstellar medium, Stars, chemistry, 13. Climate action, MOLECULES [ISM], COSMOLOGY, IONIZATION, Molecular physics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Carbon, STARS
Abstract: The interstellar delivery of carbon atoms locked into molecules might be one of the key ingredients for the emergence of life. Cyanopolyynes are carbon chains delimited at their two extremities by an atom of hydrogen and a cyano group, meaning that they could be excellent reservoirs of carbon. The simplest member, HC3N, is ubiquitous in the galactic interstellar medium and found also in external galaxies. Thus, understanding the growth of cyanopolyynes in regions forming stars similar to our Sun, and what affects them, is particularly relevant. In the framework of the IRAM/NOEMA Large Program SOLIS (Seeds Of Life In Space), we have obtained a map of two cyanopolyynes, HC3N and HC5N, in the protocluster OMC-2 FIR4. Because our Sun is thought to be born in a rich cluster, OMC-2 FIR4 is one of the closest and best known representatives of the environment in which the Sun may have been born. We find a HC3N/HC5N abundance ratio across the source in the range 1..30, with the smallest values (≤10) in FIR5 and in the eastern region of FIR4. The ratios ≤10 can be reproduced by chemical models only if: (1) the cosmic-ray ionisation rate is ∼4× 10-14 s-1; (2) the gaseous elemental ratio C/O is close to unity; and (3) oxygen and carbon are largely depleted. The large is comparable to that measured in FIR4 by previous works and was interpreted as due to a flux of energetic (≥10 MeV) particles from embedded sources. We suggest that these sources could lie east of FIR4 and FIR5. A temperature gradient across FIR4, with T decreasing from east to west by about 10 K, could also explain the observed change in the HC3N/HC5N line ratio, without the need of a cosmic ray ionisation rate gradient. However, even in this case, a high constant cosmic-ray ionisation rate (of the order of 10s s-1) is necessary to reproduce the observations. © ESO 2017. European Research Council, ERC: PALs 320620 Centre National dâ Etudes Spatiales, CNES ANR10LABX56 Canadian Institute for Theoretical Astrophysics, ICAT Conseil National de la Recherche Scientifique, CNRS-L ★ Based on observations carried out under project number L15AA with the IRAM NOEMA Interferometer. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain). ★★ The final IRAM data used in the paper (FITS format) are available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/605/A57 Acknowledgements. We thank the IRAM staff for their help in the data reduction. Many thanks to the anonymous referee for his/her constructive comments. This work was supported by the French program Physique et Chimie du Milieu In-terstellaire (PCMI) funded by the Conseil National de la Recherche Scientifique (CNRS) and Centre National d’Études Spatiales (CNES), and by a grant from LabeX Osug@2020 (Investissements d’avenir – ANR10LABX56). Partial salary support for A. Pon was provided by a Canadian Institute for Theoretical Astrophysics (CITA) National Fellowship. P.C., A. Punanova, A.C., and J.E.P. acknowledge support from the European Research Council (project PALs 320620). C.F. acknowledges founding from French space agency CNES.
Published: 2017
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20. Seeds of Life in Space (SOLIS). II. Formamide in protostellar shocks: Evidence for gas-phase formation

Author: Izaskun Jiménez-Serra, Ana Chacón-Tanarro, Claudine Kahane, Andy Pon, R. Neri, Yoko Oya, Patrice Theulé, Leonardo Testi, Audrey Coutens, Paola Caselli, Charlotte Vastel, Serena Viti, François Dulieu, Jaime E. Pineda, R. Choudhury, P. Hily-Blant, J. Ospina, Fanny Vazart, Vincenzo Barone, Ana López-Sepulcre, Ian R. Sims, Laurent Wiesenfeld, Claudio Codella, Anna Punanova, Sandrine Bottinelli, Vianney Taquet, Francesco Fontani, Jacob C. Laas, A. Jaber Al-Edhari, Linda Podio, Cecilia Ceccarelli, Satoshi Yamamoto, Nami Sakai, Felipe O. Alves, Rafael Bachiller, Emmanuel Caux, S. Spezzano, D. Quénard, Nadia Balucani, Siyi Feng, Cécile Favre, Luca Bizzocchi, Cristina Puzzarini, Bertrand Lefloch, Piero Ugliengo, Anton Vasyunin, Jonathan Holdship, Dimitrios Skouteris, Albert Rimola, E. Bianchi, Laboratoire d'Astrophysique de Grenoble (LAOG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astrofisico di Arcetri (OAA), Istituto Nazionale di Astrofisica (INAF), Università degli Studi di Perugia (UNIPG), INAF - Osservatorio Astronomico di Brera (OAB), Southern University of Science and Technology [Shenzhen] (SUSTech), 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), Queen Mary University of London (QMUL), University College of London [London] (UCL), ESAB, Universitad polytecnica de Cataluna, University of Western Ontario (UWO), Max Planck Institute for Extraterrestrial Physics (MPE), Max-Planck-Gesellschaft, 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), 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), departament de Quimica, Universitat Autònoma de Barcelona [Barcelona] (UAB), RIKEN - Institute of Physical and Chemical Research [Japon] (RIKEN), Scuola Normale Superiore di Pisa (SNS), European Southern Observatory (ESO), Physique des interactions ioniques et moléculaires (PIIM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Università degli studi di Torino (UNITO), Codella, C., Ceccarelli, C., Caselli, P., Balucani, N., Barone, V., Fontani, F., Lefloch, B., Podio, L., Viti, S., Feng, S., Bachiller, R., Bianchi, E., Dulieu, F., Jiménez-Serra, I., Holdship, J., Neri, R., Pineda, J.E., Pon, A., Sims, I., Spezzano, S., Vasyunin, A.I., Alves, F., Bizzocchi, L., Bottinelli, S., Caux, E., Chacón-Tanarro, A., Choudhury, R., Coutens, A., Favre, C., Hily-Blant, P., Kahane, C., Jaber Al-Edhari, A., Laas, J., López-Sepulcre, A., Ospina, J., Oya, Y., Punanova, A., Puzzarini, C., Quenard, D., Rimola, A., Sakai, N., Skouteris, D., Taquet, V., Testi, L., Theulé, P., Ugliengo, P., Vastel, C., Vazart, F., Wiesenfeld, L., Yamamoto, S., Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), 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 Grenoble Alpes [2016-2019] (UGA [2016-2019])-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 Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Università degli Studi di Perugia = University of Perugia (UNIPG), Southern University of Science and Technology (SUSTech), LERMA Cergy (LERMA), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), 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 de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris-Seine-Université Paris-Seine-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Universitat Autònoma de Barcelona (UAB), Università degli studi di Torino = University of Turin (UNITO), Pineda, J. E., Vasyunin, A. I., 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), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), 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)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), and Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU)
Subjects: Formamide, Abundance (chemistry), Direct evidence, Stars: formation, FOS: Physical sciences, Context (language use), Astrophysics, ISM: molecule, 01 natural sciences, chemistry.chemical_compound, 0103 physical sciences, Protostar, molecule [ISM], 010303 astronomy & astrophysics, ISM: jets and outflow, formation [Stars], ComputingMilieux_MISCELLANEOUS, Line (formation), Earth and Planetary Astrophysics (astro-ph.EP), ISM: individual objects: L1157-B1, ISM: jets and outflows, ISM: molecules, Astronomy and Astrophysics, Space and Planetary Science, Physics, [PHYS]Physics [physics], 010308 nuclear & particles physics, jets and outflow [ISM], individual objects: L1157-B1 [ISM], Astronomy and Astrophysic, Stars, chemistry, Millimeter, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Astrophysics - Earth and Planetary Astrophysics
Abstract: Context: Modern versions of the Miller-Urey experiment claim that formamide (NH$_2$CHO) could be the starting point for the formation of metabolic and genetic macromolecules. Intriguingly, formamide is indeed observed in regions forming Solar-type stars as well as in external galaxies. Aims: How NH$_2$CHO is formed has been a puzzle for decades: our goal is to contribute to the hotly debated question of whether formamide is mostly formed via gas-phase or grain surface chemistry. Methods: We used the NOEMA interferometer to image NH$_2$CHO towards the L1157-B1 blue-shifted shock, a well known interstellar laboratory, to study how the components of dust mantles and cores released into the gas phase triggers the formation of formamide. Results: We report the first spatially resolved image (size $\sim$ 9", $\sim$ 2300 AU) of formamide emission in a shocked region around a Sun-like protostar: the line profiles are blueshifted and have a FWHM $\simeq$ 5 km s$^{-1}$. A column density of $N_{\rm NH_2CHO}$ = 8 $\times$ 10$^{12}$ cm$^{-1}$, and an abundance (with respect to H-nuclei) of 4 $\times$ 10$^{-9}$ are derived. We show a spatial segregation of formamide with respect to other organic species. Our observations, coupled with a chemical modelling analysis, indicate that the formamide observed in L1157-B1 is formed by gas-phase chemical process, and not on grain surfaces as previously suggested. Conclusions: The SOLIS interferometric observations of formamide provide direct evidence that this potentially crucial brick of life is efficiently formed in the gas-phase around Sun-like protostars., 7 pages, 1 table, 5 figures, A&A Letters, in press
Published: 2017
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21. Seeds Of Life In Space (SOLIS): The Organic Composition Diversity at 300-1000 au Scale in Solar-type Star-forming Regions

Author: R. Choudhury, Emmanuel Caux, Felipe O. Alves, Jacob C. Laas, Albert Rimola, François Dulieu, Satoshi Yamamoto, Charlotte Vastel, Francesco Fontani, Serena Viti, Anton Vasyunin, Leonardo Testi, E. Bianchi, Jonathan Holdship, Ana Chacón-Tanarro, Nami Sakai, P. Hily-Blant, J. Ospina, Sandrine Bottinelli, Claudine Kahane, Andy Pon, D. Quénard, Bertrand Lefloch, Piero Ugliengo, Laurent Wiesenfeld, Ana López-Sepulcre, R. Neri, Rafael Bachiller, Cecilia Ceccarelli, Jaime E. Pineda, Claudio Codella, Vianney Taquet, Cécile Favre, Paola Caselli, Anna Punanova, A. Jaber Al-Edhari, Patrice Theulé, Linda Podio, S. Spezzano, Luca Bizzocchi, Yoko Oya, Audrey Coutens, Siyi Feng, Nadia Balucani, Ian R. Sims, Izaskun Jiménez-Serra, 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), Max Planck Institute for Extraterrestrial Physics (MPE), Max-Planck-Gesellschaft, INAF - Osservatorio Astronomico di Brera (OAB), Istituto Nazionale di Astrofisica (INAF), INAF - Osservatorio Astrofisico di Arcetri (OAA), Queen Mary University of London (QMUL), University College of London [London] (UCL), 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), Università degli Studi di Perugia (UNIPG), Università degli Studi di Firenze [Firenze], 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), University of Western Ontario (UWO), Universitat Autònoma de Barcelona [Barcelona] (UAB), RIKEN - Institute of Physical and Chemical Research [Japon] (RIKEN), 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), Physique des interactions ioniques et moléculaires (PIIM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Università degli studi di Torino (UNITO), Ural Federal University [Ekaterinburg] (UrFU), Centre National de la Recherche Scientifique (CNRS), University of Electro-Communications [Tokyo] (UEC), European Research Council (ERC) [320620, 741002], French program Physique et Chimie du Milieu Interstellaire (PCMI) - Conseil National de la Recherche Scientifique (CNRS), Centre National dEtudes Spatiales (CNES), Italian Ministero dell'Istruzione, Universita e Ricerca, through the grant Progetti Premiali iALMA [CUP C52I13000140001], Canadian Institute for Theoretical Astrophysics (CITA) National Fellowship, STFC [ST/L004801, ST/M004139], Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), 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 Grenoble Alpes [2016-2019] (UGA [2016-2019])-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 Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Università degli Studi di Perugia = University of Perugia (UNIPG), Università degli Studi di Firenze = University of Florence (UniFI), LERMA Cergy (LERMA), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA (UMR_8112)), 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 de Cergy Pontoise (UCP), Université Paris-Seine-Université Paris-Seine-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris-Seine-Université Paris-Seine-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Universitat Autònoma de Barcelona (UAB), Université de Rennes (UR)-Centre National de la Recherche Scientifique (CNRS), Università degli studi di Torino = University of Turin (UNITO), Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), 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)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -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)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France, Max-Planck-Institut fur Extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching, Germany, INAF-Osservatorio Astrofisico di Arcetri (INAF-OAA), Institut de RadioAstronomie Millimétrique (IRAM), Department of Physics and Astronomy, University College London, Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Université Fédérale Toulouse Midi-Pyrénées-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Observatorio Astronómico Nacional, Observatorio de Madrid, Alfonso XII (OAN), École normale supérieure - Paris (ENS-PSL), 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), Molécules dans l'Univers, Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères (LERMA (UMR_8112)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-CY Cergy Paris Université (CY), University of AL-Muthanna, College of Science, Physics Department, AL-Muthanna, Iraq, Department of Physics, University of Tokyo, Departament de Quimica, Universitat Autonoma de Barcelona, E-08193 Bellaterra, Spain, RIKEN The Institute of Physical and Chemical Research, Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), 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)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Università degli Studi di Firenze = University of Florence [Firenze] (UNIFI), 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), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)
Subjects: radio lines ISM, FOS: Physical sciences, Scale (descriptive set theory), Astrophysics, Type (model theory), Star (graph theory), Space (mathematics), ISM: clouds, 01 natural sciences, ISM: abundances, Spectral line, ISM molecules, Abundance (ecology), ISM: molecules, radio lines: ISM, Astronomy and Astrophysics, Space and Planetary Science, 0103 physical sciences, 14. Life underwater, 010303 astronomy & astrophysics, ISM abundances, Solar and Stellar Astrophysics (astro-ph.SR), ComputingMilieux_MISCELLANEOUS, Physics, [PHYS]Physics [physics], 010308 nuclear & particles physics, Astrophysics - Astrophysics of Galaxies, Interstellar medium, ISM clouds, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, Astrophysics of Galaxies (astro-ph.GA), Molecular physics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Order of magnitude
Abstract: Complex organic molecules have been observed for decades in the interstellar medium. Some of them might be considered as small bricks of the macromolecules at the base of terrestrial life. It is hence particularly important to understand organic chemistry in Solar-like star forming regions. In this article, we present a new observational project: SOLIS (Seeds Of Life In Space). This is a Large Project at the IRAM-NOEMA interferometer, and its scope is to image the emission of several crucial organic molecules in a sample of Solar-like star forming regions in different evolutionary stage and environments. Here, we report the first SOLIS results, obtained from analysing the spectra of different regions of the Class 0 source NGC1333-IRAS4A, the protocluster OMC-2 FIR4, and the shock site L1157-B1. The different regions were identified based on the images of formamide (NH2CHO) and cyanodiacetylene (HC5N) lines. We discuss the observed large diversity in the molecular and organic content, both on large (3000-10000 au) and relatively small (300-1000 au) scales. Finally, we derive upper limits to the methoxy fractional abundance in the three observed regions of the same order of magnitude of that measured in few cold prestellar objects, namely ~10^-12-10^-11 with respect to H2 molecules., Comment: Accepted for publication on The Astrophysical Journal
Published: 2017
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22. Collision energy dependence of state-to-state differential cross sections for rotationally inelastic scattering of H2O by He

Author: David H. Parker, Gautam Sarma, Lazaros Mavridis, Chung-Hsin Yang, Laurent Wiesenfeld, Udo Buck, Chandan Kumar Bishwakarma, Roy Scheidsbach, Sarantos Marinakis, and Ashim Kumar Saha
Subjects: Resonance-enhanced multiphoton ionization, Range (particle radiation), 010304 chemical physics, Chemistry, Forward scatter, Applied Molecular Physics, Inelastic collision, General Physics and Astronomy, Inelastic scattering, 010402 general chemistry, Collision, 01 natural sciences, 0104 chemical sciences, 0103 physical sciences, Potential energy surface, Molecular and Laser Physics, Physical and Theoretical Chemistry, Atomic physics, Excitation
Abstract: The inelastic scattering of H2O by He as a function of collision energy in the range 381 cm−1 to 763 cm−1 at an energy interval of approximately 100 cm−1 has been investigated in a crossed beam experiment using velocity map imaging. Change in collision energy was achieved by varying the collision angle between the H2O and He beam. We measured the state-to-state differential cross section (DCS) of scattered H2O products for the final rotational states JKaKc = 110, 111, 221 and 414. Rotational excitation of H2O is probed by (2 + 1) resonance enhanced multiphoton ionization (REMPI) spectroscopy. DCS measurements over a wide range of collision energies allowed us to probe the H2O–He potential energy surface (PES) with greater detail than in previous work. We found that a classical approximation of rotational rainbows can predict the collision energy dependence of the DCS. Close-coupling quantum mechanical calculations were used to produce DCS and partial cross sections. The forward–backward ratio (FBR), is introduced here to compare the experimental and theoretical DCS. Both theory and experiments suggest that an increase in the collision energy is accompanied with more forward scattering.
Published: 2017

23. History of the solar-type protostar IRAS 16293–2422 as told by the cyanopolyynes

Author: A. Jaber Al-Edhari, Emmanuel Caux, François Lique, Nadia Balucani, Alexandre Faure, D. Quénard, Claudine Kahane, Serena Viti, Laurent Wiesenfeld, E. Mendoza, Bertrand Lefloch, Cecilia Ceccarelli, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), 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 Grenoble Alpes [2016-2019] (UGA [2016-2019])-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 Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Università degli Studi di Perugia (UNIPG), Institut de recherche en astrophysique et planétologie (IRAP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-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)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Ondes et Milieux Complexes (LOMC), Centre National de la Recherche Scientifique (CNRS)-Université Le Havre Normandie (ULH), Normandie Université (NU)-Normandie Université (NU), Centro de Investigaciones Energéticas Medioambientales y Tecnológicas [Madrid] (CIEMAT), 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), Univ Toulouse UPS, Ctr Etud Spatiale Rayonnements, F-31062 Toulouse 9, France, Centre Etud Spatiale Rayonnements Toulouse, Neurobiologie de l'apprentissage, de la mémoire et de la communication (NAMC), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), Université Le Havre Normandie (ULH), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Centre Scientifique et Technique du Bâtiment (CSTB Saint Martin d'Hères), Centre Scientifique et Technique du Bâtiment (CSTB), Università degli Studi di Perugia = University of Perugia (UNIPG), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)
Subjects: Astrochemistry, 010504 meteorology & atmospheric sciences, FOS: Physical sciences, Context (language use), Astrophysics, 01 natural sciences, Spectral line, IRAS 16293-2422, chemistry.chemical_compound, Abundances - ISM, 0103 physical sciences, Cyanoacetylene, Protostar, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR), ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Physics, [PHYS]Physics [physics], Cyanopolyyne, Molecular cloud, Astrochemistry - ISM, Individual objects, Astronomy and Astrophysics, Space and Planetary Science, Astrophysics - Astrophysics of Galaxies, Interstellar medium, chemistry, Astrophysics - Solar and Stellar Astrophysics, 13. Climate action, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA)
Abstract: Cyanopolyynes are chains of carbon atoms with an atom of hydrogen and a CN group on either side. They are detected almost everywhere in the ISM, as well as in comets. In the past, they have been used to constrain the age of some molecular clouds, since their abundance is predicted to be a strong function of time. We present an extensive study of the cyanopolyynes distribution in the solar-type protostar IRAS16293-2422 based on TIMASSS IRAM-30m observations. The goals are (i) to obtain a census of the cyanopolyynes in this source and of their isotopologues; (ii) to derive how their abundance varies across the protostar envelope; and (iii) to obtain constraints on the history of IRAS16293-2422. We detect several lines from HC3N and HC5N, and report the first detection of DC3N, in a solar-type protostar. We found that the HC3N abundance is roughly constant (~1.3x10^(-11)) in the outer cold envelope of IRAS16293-2422, and it increases by about a factor 100 in the inner region where Tdust>80K. The HC5N has an abundance similar to HC3N in the outer envelope and about a factor of ten lower in the inner region. The HC3N abundance derived in the inner region, and where the increase occurs, also provide strong constraints on the time taken for the dust to warm up to 80K, which has to be shorter than ~10^3-10^4yr. Finally, the cyanoacetylene deuteration is about 50\% in the outer envelope and, Accepted for publication in A&A
Published: 2017
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24. New insights on the HCl abundance in the interstellar medium

Author: Laurent Wiesenfeld, François Lique, Alain Faure, Mathieu Lanza, Yulia N. Kalugina, Laboratoire Ondes et Milieux Complexes (LOMC), Centre National de la Recherche Scientifique (CNRS)-Université Le Havre Normandie (ULH), and Normandie Université (NU)-Normandie Université (NU)
Subjects: [PHYS]Physics [physics], Physics, Abundance (chemistry), chemistry.chemical_element, Astronomy and Astrophysics, 7. Clean energy, Interstellar medium, chemistry, [SDU]Sciences of the Universe [physics], Space and Planetary Science, Potential energy surface, Chlorine, Molecule, Physics::Chemical Physics, Atomic physics, ComputingMilieux_MISCELLANEOUS, Astrophysics::Galaxy Astrophysics, Excitation, Line (formation)
Abstract: HCl is supposed to be one of the main chlorine carriers in the interstellar medium (ISM). Then, accurate knowledge of chlorine chemistry requires accurate estimating the HCl abundance in molecularcloudswhichinturnrequiresthecalculationofcollisionalexcitationratecoefficients for the HCl molecule due to collisions with the most abundant collisional partner in the ISM. In this paper, we report theoretical calculations of the HCl–H2 rotationally inelastic rate coefficients. Using a recently developed potential energy surface, we have computed rate coefficients between the first 11 rotational levels of HCl for temperatures ranging from 5 to 300 K. These new HCl–H2 rate coefficients were compared to the available HCl–He rate coefficients currently used for astrophysical modelling. As one would expect, significant differences were found between new HCl–H2 and previous HCl–He rate coefficients. As a first application, we simulate the excitation of HCl in typical star-forming regions and in protostellar shocks. Electron-impact excitation is also included. It is found that the new H2 rate coefficients significantly increase the simulated line intensities. As a consequence, HCl abundance derived from the observations will be significantly reduced by the use of the present rate coefficients, confirming that HCl may not be the main chlorine carrier in the ISM.
Published: 2014
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25. Pressure broadening of water and carbon monoxide transitions by molecular hydrogen at high temperatures

Author: Brian J. Drouin, Alain Faure, Laurent Wiesenfeld, and Jonathan Tennyson
Subjects: Range (particle radiation), Radiation, Materials science, Brown dwarf, 01 natural sciences, 7. Clean energy, Atomic and Molecular Physics, and Optics, Exoplanet, chemistry.chemical_compound, Stars, chemistry, 0103 physical sciences, Radiative transfer, Astrophysics::Earth and Planetary Astrophysics, Atomic physics, 010306 general physics, Random phase approximation, 010303 astronomy & astrophysics, Spectroscopy, Water vapor, Carbon monoxide
Abstract: Water and carbon monoxide are two major compounds in the predominantly H2 atmospheres of stars, brown dwarfs and extrasolar planets. Recent radiative transfer models suggest that there is an urgent need for data on the pressure broadening of molecular transitions by H2 at high temperatures. We present a set of theoretical H2 pressure broadening parameters for 228 H2O transitions in the range of 10–20,000 GHz and 30 CO transitions in the 115–3500 GHz region. These parameters are appropriate for temperatures between 200 and 3000 K. The random phase approximation is employed to derive the broadening parameters from recent state-of-the-art inelastic collisional rate coefficients. This approximation is compared both to full close-coupling calculations and to available experimental data. It is shown to be valid at temperatures above 200 K, as expected from theoretical considerations, with an accuracy of about 25%.
Published: 2013
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26. Collisional excitation of HC 3 N by para- and ortho-H 2

Author: François Lique, Alexandre Faure, Laurent Wiesenfeld, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), 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 Grenoble Alpes [2016-2019] (UGA [2016-2019])-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 Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Laboratoire Ondes et Milieux Complexes (LOMC), Centre National de la Recherche Scientifique (CNRS)-Université Le Havre Normandie (ULH), and Normandie Université (NU)-Normandie Université (NU)
Subjects: FOS: Physical sciences, Kinetic energy, 01 natural sciences, chemistry.chemical_compound, Physics - Chemical Physics, 0103 physical sciences, Cyanoacetylene, 010306 general physics, 010303 astronomy & astrophysics, Quantum, Hyperfine structure, Trajectory (fluid mechanics), Collisional excitation, Astrophysics::Galaxy Astrophysics, ComputingMilieux_MISCELLANEOUS, Chemical Physics (physics.chem-ph), Physics, [PHYS]Physics [physics], Hydrogen molecule, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, chemistry, Space and Planetary Science, [SDU]Sciences of the Universe [physics], Astrophysics of Galaxies (astro-ph.GA), Atomic physics, Excitation
Abstract: New calculations for rotational excitation of cyanoacetylene by collisions with hydrogen molecules are performed to include the lowest 38 rotational levels of HC3N and kinetic temperatures to 300 K. Calculations are based on the interaction potential of Wernli et al. A&A, 464, 1147 (2007) whose accuracy is checked against spectroscopic measurements of the HC3N-H2 complex. The quantum coupled-channel approach is employed and complemented by quasi-classical trajectory calculations. Rate coefficients for ortho-H2 are provided for the first time. Hyperfine resolved rate coefficients are also deduced. Collisional propensity rules are discussed and comparisons between quantum and classical rate coefficients are presented. This collisional data should prove useful in interpreting HC3N observations in the cold and warm ISM, as well as in protoplanetary disks., 8 pages, 2 tables, 4 figures, accepted for publication in MNRAS
Published: 2016
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27. Collisional excitation of doubly and triply deuterated ammonia ND_2H and ND_3 by H_2

Author: E. Roueff, Claire Rist, Maryvonne Gerin, D. C. Lis, Alexandre Faure, Pierre Hily-Blant, Laurent Wiesenfeld, F. Daniel, and Aurore Bacmann
Subjects: Physics, 010304 chemical physics, Scattering, Thermodynamic equilibrium, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, 01 natural sciences, Ammonia, chemistry.chemical_compound, chemistry, Deuterium, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, Potential energy surface, Molecule, Isotopologue, Atomic physics, 010303 astronomy & astrophysics, Collisional excitation, Astrophysics::Galaxy Astrophysics
Abstract: The availability of collisional rate coefficients is a prerequisite for an accurate interpretation of astrophysical observations, since the observed media often harbour densities where molecules are populated under non--LTE conditions. In the current study, we present calculations of rate coefficients suitable to describe the various spin isomers of multiply deuterated ammonia, namely the ND$_2$H and ND$_3$ isotopologues. These calculations are based on the most accurate NH$_3$--H$_2$ potential energy surface available, which has been modified to describe the geometrical changes induced by the nuclear substitutions. The dynamical calculations are performed within the close--coupling formalism and are carried out in order to provide rate coefficients up to a temperature of $T$ = 50K. For the various isotopologues/symmetries, we provide rate coefficients for the energy levels below $\sim$ 100 cm$^{-1}$. Subsequently, these new rate coefficients are used in astrophysical models aimed at reproducing the NH$_2$D, ND$_2$H and ND$_3$ observations previously reported towards the prestellar cores B1b and 16293E. We thus update the estimates of the corresponding column densities and find a reasonable agreement with the previous models. In particular, the ortho--to--para ratios of NH$_2$D and NHD$_2$ are found to be consistent with the statistical ratios.
Published: 2016

28. Deuteration of ammonia in the starless core Ophiuchus/H-MM1

Author: Erik Rosolowsky, Jaime E. Pineda, Olli Sipilä, Paola Caselli, Stephan Schlemmer, Anna Punanova, Jorma Harju, Philip C. Myers, Rachel Friesen, F. Daniel, Alexandre Faure, Rolf Güsten, Yancy L. Shirley, Claire Rist, Pierre Hily-Blant, Laurent Wiesenfeld, and Department of Physics
Subjects: NITROGEN HYDRIDES, Astrochemistry, PRE-PROTOSTELLAR COLLAPSE, FOS: Physical sciences, Astrophysics, MOLECULAR CLOUD, ISM: clouds, 01 natural sciences, ISM: abundances, PRESTELLAR CORES, RADIO-ASTRONOMICAL SPECTROSCOPY, 0103 physical sciences, GOULD BELT SURVEY, 010303 astronomy & astrophysics, Hyperfine structure, Physics, 010304 chemical physics, astrochemistry, European research, Molecular cloud, Astronomy and Astrophysics, 115 Astronomy, Space science, Astrophysics - Astrophysics of Galaxies, ISM: molecules, DARK CLOUDS, Core (optical fiber), DEUTERIUM FRACTIONATION, 13. Climate action, Space and Planetary Science, Extraterrestrial life, Astrophysics of Galaxies (astro-ph.GA), HYPERFINE-STRUCTURE, Ophiuchus, BONNOR-EBERT SPHERES
Abstract: Ammonia and its deuterated isotopologues probe physical conditions in dense molecular cloud cores. With the aim of testing the current understanding of the spin-state chemistry of these molecules, we observed spectral lines of NH3, NH2D, NHD2, ND3, and N2D+ towards a dense, starless core in Ophiuchus with the APEX, GBT, and IRAM 30-m telescopes. The observations were interpreted using a gas-grain chemistry model combined with radiative transfer calculations. The chemistry model distinguishes between the different nuclear spin states of light hydrogen molecules, ammonia, and their deuterated forms. High deuterium fractionation ratios with NH2D/NH3=0.4, NHD2/NH2D=0.2, and ND3/NHD2=0.06 were found in the core. The observed ortho/para ratios of NH2D and NHD2 are close to the corresponding nuclear spin statistical weights. The chemistry model can approximately reproduce the observed abundances, but predicts uniformly too low ortho/para-NH2D, and too large ortho/para-NHD2 ratios. The longevity of N2H+ and NH3 in dense gas, which is prerequisite to their strong deuteration, can be attributed to the chemical inertia of N2 on grain surfaces. The discrepancies between the chemistry model and the observations are likely to be caused by the fact that the model assumes complete scrambling in principal gas-phase deuteration reactions of ammonia, which means that all the nuclei are mixed in reactive collisions. If, instead, these reactions occur through proton hop/hydrogen abstraction processes, statistical spin ratios are to be expected. The present results suggest that while the deuteration of ammonia changes with physical conditions and time, the nuclear spin ratios of ammonia isotopologues do not probe the evolutionary stage of a cloud., Comment: to appear in Astronomy & Astrophysics
Published: 2016
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29. Rotational excitation of mono- and doubly-deuterated water by hydrogen molecules

Author: Cecilia Ceccarelli, Laurent Wiesenfeld, Yohann Scribano, and Alain Faure
Subjects: Physics, Hydrogen molecule, Astronomy and Astrophysics, 010402 general chemistry, 01 natural sciences, 0104 chemical sciences, law.invention, Interaction potential, Orders of magnitude (time), Deuterium, Space and Planetary Science, law, 0103 physical sciences, Radiative transfer, Maser, Atomic physics, 010303 astronomy & astrophysics, Excitation
Abstract: Rate coefficients for rotational transitions in HDO and D2O induced by H2 collisions below 300 K are presented. Calculations have been performed at the close-coupling and coupledstates levels with the deuterated variants of the H2O–H2 interaction potential of Valiron et al. The HDO–H2 and D2O–H2 rate coefficients are compared to the corresponding rate coefficients for HDO–He and H2O–H2, respectively. Significant differences are observed. In particular the new HDO rate coefficients are found to be significantly larger (by up to three orders of magnitude) than the corresponding HDO–He rate coefficients. The impact of the new HDO rate coefficients is examined with the help of non-LTE radiative transfer calculations. A number of potential HDO maser lines are finally identified, in particular the 80.6 GHz (11,0–11,1) transition.
Published: 2011
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30. Theoretical Investigation of the Isomerization of trans-HCOH to H2CO: An Example of a Water-Catalyzed Reaction

Author: Laurent Wiesenfeld, Denis Duflot, Cecilia Ceccarelli, Claudine Kahane, Céline Toubin, Phillip Peters, Alexandre Faure, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG ), Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-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), Laboratoire de Physique des Lasers, Atomes et Molécules - UMR 8523 (PhLAM), Université de Lille-Centre National de la Recherche Scientifique (CNRS), Observatoire des Sciences de l'Univers de Grenoble (OSUG), and 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)
Subjects: 010304 chemical physics, Chemistry, Ab initio, Context (language use), Activation energy, Hydrogen atom, 010402 general chemistry, Photochemistry, 01 natural sciences, 0104 chemical sciences, Catalysis, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Reaction rate, Computational chemistry, 0103 physical sciences, Density functional theory, Physical and Theoretical Chemistry, Isomerization
Abstract: International audience; A concerted hydrogen atom transfer mechanism has been elucidated for the isomerization of trans-HCOH to H(2)CO using a variety of ab initio and density functional theory methods. This work places specific emphasis on the role water molecules can play as a catalyst for this reaction and the mechanism by which this is achieved. This is of particular importance in the context of molecular ices in the interstellar medium because the presence of water in this reaction reduces the activation energy by at least 80%, which is accompanied by a significant enhancement of the reaction rate, at ≤300 K.
Published: 2011
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31. Collisional excitation of doubly deuterated ammonia ND2H by para-H2

Author: Evelyne Roueff, Laurent Wiesenfeld, Alexandre Faure, and Emmanuele Scifoni
Subjects: Physics, chemistry.chemical_element, Astronomy and Astrophysics, Astrophysics, chemistry, Deuterium, Space and Planetary Science, Potential energy surface, Radiative transfer, Atomic physics, Ground state, Collisional excitation, Helium, Order of magnitude, Excitation
Abstract: Collisional de-excitation rates of partially deuterated molecules are different from the fully hydrogenated species because of lowering of symmetry. We compute the collisional (de)excitation rates of ND2H by ground state para-H2, extending the previous results for He- lium. We describe the changes in the potential energy surface of NH3- H2 involved by the pres- ence of two deuterium nuclei. Cross sections are calculated within the full close-coupling ap- proach and augmented with coupled-state calculations. Collisional rate coefficients are given between 5 and 35 K, a range of temperatures which is relevant to cold interstellar conditions. We find that the collisional rates of ND2H by H2 are about one order of magnitude higher than those obtained with Helium as perturber. These results are essential to radiative transfer modelling and will allow to interpret the millimeter and submillimeter detections of ND2H with better constraints than previously.
Published: 2011
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32. Erratum: Collisional excitation of NH3 by atomic and molecular hydrogen

Author: F. Daniel, N. Bouhafs, Claire Rist, Alexandre Faure, F. Dumouchel, Laurent Wiesenfeld, François Lique, 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 Ondes et Milieux Complexes (LOMC), Université Le Havre Normandie (ULH), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), 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 Grenoble Alpes [2016-2019] (UGA [2016-2019])-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 Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Centre National de la Recherche Scientifique (CNRS)-Université Le Havre Normandie (ULH), and Normandie Université (NU)-Normandie Université (NU)
Subjects: Physics, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010304 chemical physics, Hydrogen molecule, Astronomy and Astrophysics, 01 natural sciences, [SDU]Sciences of the Universe [physics], Space and Planetary Science, 0103 physical sciences, Radiative transfer, Atomic physics, 010303 astronomy & astrophysics, Collisional excitation, ComputingMilieux_MISCELLANEOUS
Abstract: International audience
Published: 2018
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33. On the robustness of the ammonia thermometer

Author: Emanuele Scifoni, Laurent Wiesenfeld, Sébastien Maret, Alain Faure, Laboratoire d'Astrophysique de Grenoble (LAOG), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, 010304 chemical physics, Mean kinetic temperature, Calibration curve, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, Excitation temperature, Kinetic energy, Astrophysics - Astrophysics of Galaxies, 01 natural sciences, [SDU]Sciences of the Universe [physics], Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), Thermometer, Metastability, 0103 physical sciences, Potential energy surface, Physics::Chemical Physics, Atomic physics, 010303 astronomy & astrophysics, Astrophysics::Galaxy Astrophysics, Excitation
Abstract: Ammonia inversion lines are often used as probes of the physical conditions in the dense ISM. The excitation temperature between the first two para metastable (rotational) levels is an excellent probe of the gas kinetic temperature. However, the calibration of this ammonia thermometer depends on the accuracy of the collisional rates with H2. Here we present new collisional rates for ortho-NH3 and para-NH3 colliding with para-H2 (J=0) and we investigate the effects of these new rates on the excitation of ammonia. Scattering calculations employ a new, high accuracy, potential energy surface computed at the coupled-cluster CCSD(T) level with a basis set extrapolation procedure. Rates are obtained for all transitions involving ammonia levels with J, Accepted for publication in the MNRAS
Published: 2009
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34. Electron-impact rotational excitation of : relevance for thermalization and dissociation dynamics

Author: Pierre Valiron, Laurent Wiesenfeld, Alexandre Faure, and Jonathan Tennyson
Subjects: Physics, Thermalisation, General Mathematics, General Engineering, General Physics and Astronomy, Plasma, Electron, Atomic physics, Excitation, Dissociative recombination, Electron ionization, Dissociation (chemistry), Ion
Abstract: Electrons are known to be efficient in rotationally exciting molecular ions in low-density astrophysical plasmas. Rotational excitation of molecular ions has also been shown to affect the measured values of dissociative recombination (DR) rate coefficients. Thus, electron collisions with are expected to play a significant role in thermalization and dissociation dynamics of this ion, both in the laboratory and in space. Using the molecular R -matrix method combined with the adiabatic-nuclei-rotation approximation, we have computed new rate coefficients for the rotational excitation of by electrons at temperatures from 10 to 10 000 K. De-excitation rates are found to amount to a few 10 −7 cm 3 s −1 below 1000 K, i.e. comparable in magnitude to that of DR. In astrophysical environments where the electron fraction exceeds 10 −4 , electron collisions are thus expected to contribute to the non-thermal rotational distribution of . The competition between electron and neutral collisions is discussed in the context of recent observations of towards Galactic centre sources.
Published: 2006
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35. Influence of a new potential energy surface on the rotational (de)excitation of H$_{\mathsf 2}$O by H$_{\mathsf 2}$ at low temperature

Author: Pierre Valiron, Michael Wernli, Laurent Wiesenfeld, Jonathan Tennyson, A. Faure, Jozef Noga, M.-L. Dubernet, A. Grosjean, Claire Rist, and F. Daniel
Subjects: Physics, 010304 chemical physics, Scattering, chemistry.chemical_element, Astronomy and Astrophysics, Kinetic energy, 01 natural sciences, Interaction potential, Reaction rate constant, chemistry, Space and Planetary Science, 0103 physical sciences, Potential energy surface, Atomic physics, Close coupling, 010303 astronomy & astrophysics, Excitation, Helium
Abstract: Aims.Using a newly determined 5D potential energy surface for H2-H2O we provide an extended and revised set of rate coefficients for de-excitation of the lowest 10 para- and 10 ortho- rotational levels of H2O by collisions with para-(j=0) and ortho-H2(j=1), for kinetic temperatures from 5 K to 20 K. Methods.Our close coupling scattering calculations involve a slightly improved set of coupled channels with respect to previous calculations. In addition, we discuss the influence of several features of this new 5D interaction on the rotational excitation cross sections. Results. The new interaction potential leads to significantly different rate coefficients for collisions with para-H2 (j=0). In particular the de-excitation rate coefficient for the 110 to 101 transition is increased by up to 300% at 5 K. At 20 K this increase is 75%. Rate coefficients for collisions with ortho-H2(j=1) are modified to a lesser extent, by up to 40%. The influence of the new potential on collisions with both para-(j=0) and ortho-H2(j=1) is expected to become less pronounced at higher temperatures.
Published: 2006
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36. Local separatrices for Hamiltonians with symmetries

Author: Laurent Wiesenfeld
Subjects: Invariant manifold, Mathematical analysis, General Physics and Astronomy, Statistical and Nonlinear Physics, Stable manifold theorem, Mathematics::Geometric Topology, Stable manifold, Homoclinic connection, Homogeneous space, Mathematics::Differential Geometry, Homoclinic orbit, Mathematics::Symplectic Geometry, Mathematical Physics, Saddle, Center manifold, Mathematical physics, Mathematics
Abstract: We consider dynamics generated by Hamiltonians with three degrees of freedom and symmetries. It is shown that locally, away from a possible saddle equilibrium, some codimension-1 invariant manifold may exist. They are stable/unstable manifolds of a codimension-2 hyperbolic invariant manifold. This structure appears when some periodic orbits constitutive of the Arnold web have bifurcated and become linearly unstable. This result generalizes the existence of normally hyperbolic invariant manifolds and their codimension-1 stable/unstable manifolds in the vicinity of an unstable ⊗ (stable)2 equilibrium point.
Published: 2004
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37. Gas Phase Chemistry

Author: Juraj Glosík, Laurent Wiesenfeld, Wolf D. Geppert, Oskar Asvany, Daniel Wolf Savin, Andreas Wolf, Holger Kreckel, Stephan Schlemmer, and David H. Parker
Subjects: Chemistry, Chemical physics, Atomic physics, Gas phase
Published: 2014
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38. Collisional excitation of singly deuterated ammonia NH$_2$D by H$_2$

Author: Evelyne Roueff, A. Faure, D. C. Lis, F. Daniel, Laurent Wiesenfeld, P. Hily-Blant, 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), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), École normale supérieure - Paris (ENS-PSL), 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), Université Paris-Seine-Université Paris-Seine-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), 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), and École normale supérieure - Paris (ENS Paris)
Subjects: Physics, [PHYS]Physics [physics], 010304 chemical physics, Scattering, Equilibrium conditions, FOS: Physical sciences, Astronomy and Astrophysics, 01 natural sciences, Astrophysics - Astrophysics of Galaxies, Ammonia, chemistry.chemical_compound, Low energy, chemistry, Deuterium, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, Potential energy surface, Molecule, Atomic physics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], 010303 astronomy & astrophysics, Collisional excitation, ComputingMilieux_MISCELLANEOUS
Abstract: The availability of collisional rate coefficients with H$_2$ is a pre-requisite for interpretation of observations of molecules whose energy levels are populated under non local thermodynamical equilibrium conditions. In the current study, we present collisional rate coefficients for the NH$_2$D / para--H$_2$($J_2 = 0,2$) collisional system, for energy levels up to $J_\tau = 7_7$ ($E_u$$\sim$735 K) and for gas temperatures in the range $T = 5-300$K. The cross sections are obtained using the essentially exact close--coupling (CC) formalism at low energy and at the highest energies, we used the coupled--states (CS) approximation. For the energy levels up to $J_\tau = 4_2$ ($E_u$$\sim$215 K), the cross sections obtained through the CS formalism are scaled according to a few CC reference points. These reference points are subsequently used to estimate the accuracy of the rate coefficients for higher levels, which is mainly limited by the use of the CS formalism. Considering the current potential energy surface, the rate coefficients are thus expected to be accurate to within 5\% for the levels below $J_\tau = 4_2$, while we estimate an accuracy of 30\% for higher levels.
Published: 2014
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39. OBSERVING ORGANIC MOLECULES IN INTERSTELLAR GASES: NON EQUILIBRIUM EXCITATION

Author: Alexandre Faure, Krzysztof Szalewicz, Anthony J. Remijan, and Laurent Wiesenfeld
Subjects: Physics, Chemical physics, Astrophysics, Excitation, Organic molecules
Published: 2014
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40. Near-resonant rotational energy transfer in HCl–H 2 inelastic collisions

Author: Laurent Wiesenfeld, Mathieu Lanza, François Lique, Yulia N. Kalugina, Laboratoire Ondes et Milieux Complexes (LOMC), Centre National de la Recherche Scientifique (CNRS)-Université Le Havre Normandie (ULH), Normandie Université (NU)-Normandie Université (NU), and Томский государственный университет Физический факультет Кафедра оптики и спектроскопии
Subjects: [PHYS]Physics [physics], 010304 chemical physics, Chemistry, General Physics and Astronomy, водород, столкновения неупругие, Electronic structure, 01 natural sciences, 7. Clean energy, Bond-dissociation energy, Potential energy, Rotational energy, symbols.namesake, Coupled cluster, поверхности потенциальной энергии, 0103 physical sciences, Potential energy surface, symbols, Van der Waals radius, Physical and Theoretical Chemistry, van der Waals force, Atomic physics, 010303 astronomy & astrophysics, Хлористый водород, ComputingMilieux_MISCELLANEOUS
Abstract: We present a new four-dimensional (4D) potential energy surface for the HCl-H2 van der Waals system. Both molecules were treated as rigid rotors. Potential energy surface was obtained from electronic structure calculations using a coupled cluster with single, double, and perturbative triple excitations method. The four atoms were described using the augmented correlation-consistent quadruple zeta basis set and bond functions were placed at mid-distance between the HCl and H2 centers of mass for a better description of the van der Waals interaction. The global minimum is characterized by the well depth of 213.38 cm(-1) corresponding to the T-shape structure with H2 molecule on the H side of the HCl molecule. The dissociation energies D0 are 34.7 cm(-1) and 42.3 cm(-1) for the complex with para- and ortho-H2, respectively. These theoretical results obtained using our new PES are in good agreement with experimental values [D. T. Anderson, M. Schuder, and D. J. Nesbitt, Chem. Phys. 239, 253 (1998)]. Close coupling calculations of the inelastic integral rotational cross sections of HCl in collisions with para-H2 and ortho-H2 were performed at low and intermediate collisional energies. Significant differences exist between para- and ortho-H2 results. The strongest collision-induced rotational HCl transitions are the transitions with Δj = 1 for collisions with both para-H2 and ortho-H2. Rotational relaxation of HCl in collision with para-H2 in the rotationally excited states j = 2 is dominated by near-resonant energy transfer.
Published: 2014
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41. The CHESS survey of the L1157-B1 bow-shock: high and low excitation water vapor

Author: Brunella Nisini, Sylvie Cabrit, Serena Viti, A. M. di Giorgio, Bertrand Lefloch, Gemma Busquet, Cecilia Ceccarelli, M. Benedettini, Claudio Codella, A. I. Gómez-Ruiz, Laurent Wiesenfeld, Antoine Gusdorf, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG ), Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-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), Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA), 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), Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS), INAF - Osservatorio Astronomico di Roma (OAR), Istituto Nazionale di Astrofisica (INAF), 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), and École normale supérieure - Paris (ENS-PSL)
Subjects: Physics, 010504 meteorology & atmospheric sciences, Molecular cloud, FOS: Physical sciences, Astronomy and Astrophysics, Astrophysics, 01 natural sciences, Astrophysics - Astrophysics of Galaxies, Spectral line, 13. Climate action, Space and Planetary Science, Astrophysics of Galaxies (astro-ph.GA), 0103 physical sciences, Protostar, Outflow, Bow shock (aerodynamics), [SDU.ASTR.GA]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Galactic Astrophysics [astro-ph.GA], 010303 astronomy & astrophysics, Water vapor, Excitation, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Line (formation)
Abstract: Molecular outflows powered by young protostars strongly affect the kinematics and chemistry of the natal molecular cloud through strong shocks resulting in substantial modifications of the abundance of several species. As part of the "Chemical Herschel Surveys of Star forming regions" guaranteed time key program, we aim at investigating the physical and chemical conditions of H20 in the brightest shock region B1 of the L1157 molecular outflow. We observed several ortho- and para-H2O transitions using HIFI and PACS instruments on board Herschel, providing a detailed picture of the kinematics and spatial distribution of the gas. We performed a LVG analysis to derive the physical conditions of H2O shocked material, and ultimately obtain its abundance. We detected 13 H2O lines probing a wide range of excitation conditions. PACS maps reveal that H2O traces weak and extended emission associated with the outflow identified also with HIFI in the o-H2O line at 556.9 GHz, and a compact (~10") bright, higher-excitation region. The LVG analysis of H2O lines in the bow-shock show the presence of two gas components with different excitation conditions: a warm (Tkin~200-300 K) and dense (n(H2)~(1-3)x10^6 cm-3) component with an assumed extent of 10" and a compact (~2"-5") and hot, tenuous (Tkin~900-1400 K, n(H2)~10^3-10^4 cm-3) gas component, which is needed to account for the line fluxes of high Eu transitions. The fractional abundance of the warm and hot H2O gas components is estimated to be (0.7-2)x10^{-6} and (1-3)x10^{-4}, respectively. Finally, we identified an additional component in absorption in the HIFI spectra of H2O lines connecting with the ground state level, probably arising from the photodesorption of icy mantles of a water-enriched layer at the edges of the cloud., Accepted for publication in A&A. 12 pages, 9 figures, 4 tables
Published: 2014
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42. Impenetrable Barriers in Phase-Space

Author: Charles Jaffé, Laurent Wiesenfeld, Turgay Uzer, and Stephen Wiggins
Subjects: Physics, Dynamical systems theory, General Physics and Astronomy, Transition of state, Space (mathematics), Mathematical Operators, symbols.namesake, Transition state theory, Phase space, symbols, Normally hyperbolic invariant manifold, Statistical physics, Hamiltonian (quantum mechanics)
Abstract: Dynamical systems theory is used to construct a general phase-space version of transition state theory. Special multidimensional separatrices are found which act as impenetrable barriers in phase-space between reacting and nonreacting trajectories. The elusive momentum-dependent transition state between reactants and products is thereby characterized. A practical algorithm is presented and applied to a strongly coupled Hamiltonian.
Published: 2001
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43. A quantum and semiclassical study of dynamical resonances in the C+NO→CN+O reaction

Author: Aron Kuppermann, Bruce Lambert, Laurent Wiesenfeld, and Ravinder Abrol
Subjects: Physics, Chemical kinetics, Scattering, Strong interaction, Potential energy surface, General Physics and Astronomy, Semiclassical physics, Physical and Theoretical Chemistry, Atomic physics, Quantum, Caltech Library Services, Eigenvalues and eigenvectors, WKB approximation
Abstract: Accurate quantum mechanical reactive scattering calculations were performed for the collinear C+NO-->CN+O reaction using a polynomial-modified London Eyring Polanyi Sato (PQLEPS) potential energy surface (PES), which has a 4.26 eV deep well in the strong interaction region, and a reference LEPS PES, which has no well in that region. The reaction probabilities obtained for both PESs show signatures for resonances. These resonances were characterized by calculating the eigenvalues and eigenvectors of the collision lifetime matrix as a function of energy. Many resonances were found for scattering on both PESs, indicating that the potential well in the PQLEPS PES does not play the sole role in producing resonances in this relatively heavy atom system and that Feshbach processes occur for both PESs. However, the well in the PQLEPS PES is responsible for the differences in the energies, lifetimes, and compositions of the corresponding resonance states. These resonances are also interpreted in terms of simple periodic orbits supported by both PESs (using the WKB formalism), to further illustrate the role played by that potential well on the dynamics of this reaction. The existence of the resonances is associated with the dynamics of the long-lived CNO complex, which is much different than that of systems having an activation barrier. Although these results were obtained for a collinear model of the reaction, its collinearly-dominated nature suggests that related resonant behavior may occur in the real world.
Published: 2001
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44. Temperature dependence of fast neutral–neutral reactions: a triatomic model study

Author: Laurent Wiesenfeld, Pierre Valiron, and Alexandre Faure
Subjects: education.field_of_study, Toy model, Chemistry, Triatomic molecule, Monte Carlo method, Population, General Physics and Astronomy, Thermodynamics, Inverse, Atmospheric temperature range, Molecular physics, Reaction rate, Reaction rate constant, Physical and Theoretical Chemistry, education
Abstract: Some neutral–neutral reactions are known to proceed rapidly at low temperatures as a consequence of strong inverse temperature power-law dependences of the rate constants. Previous calculations, based on capture approximations, failed to account for these experimental data. In this article, short-range effects (subsequent to capture) are investigated using a simple planar atom–diatom toy model based on pairwise atomic interactions. Reaction rate constants have been estimated in the temperature range of 25–300 K using a quasi-classical trajectory Monte Carlo approach. It is shown that a small short-range barrier in the entrance valley may significantly influence the reactivity. In particular, our crude triatomic model can reproduce a strong inverse temperature dependence of the rate constant in good agreement with experimental evidence for more complex systems. These predictions are interpreted using a 3-D representation of the effective potential surfaces, illustrating the crucial importance of vector correlations between partial angular momenta. Thus, the strong inverse power-law temperature dependence of the rate constant may be attributed to the population of higher rotational states of the reactants with increasing temperature.
Published: 2000
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45. A fully geometrical analysis of indirect reactive scattering

Author: Hicham Wadi and Laurent Wiesenfeld
Subjects: Surface (mathematics), Physics, Reaction rate, Classical mechanics, Intersection, Geometric analysis, Antisymmetric relation, Scattering, General Physics and Astronomy, Halo, Configuration space, Physical and Theoretical Chemistry
Abstract: The classical dynamics of 2 degree-of-freedom scattering may be geometrically analyzed by means of an extension of the periodic orbit dividing surface theory. The C+NO reaction is taken as an example. We show that the antisymmetric stretch provides a new analyzing tool because its basin of attraction extends throughout the allowed configuration space, even if it does not divide the reaction channel into a reactant part and a product part. We analyze low-energy collisions and show that the vibrational transition probabilities may be traced back to areas of intersecting surfaces. At high energy, the total reaction rate is also calculated by intersection areas. The importance of scattering chaos is shown by surrounding the entrance and exit gates of the reaction by halos.
Published: 1999
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46. The Vibron Model for Methane: Stretch–Bend Interactions

Author: Laurent Wiesenfeld
Subjects: Physics, Infrared, Anharmonicity, Vibrational spectrum, Atomic and Molecular Physics, and Optics, Methane, chemistry.chemical_compound, chemistry, Physics::Chemical Physics, Physical and Theoretical Chemistry, Atomic physics, Spectroscopy, Excitation, Energy (signal processing), Fermi Gamma-ray Space Telescope
Abstract: The full vibrational spectrum of methane is calculated, with up to four quanta of excitation. An anharmonic local mode model, the vibron model, is used. It includes all stretch and bend modes as well as Fermi 1:2 resonances between them. All energy levels below 6000 cm −1 are calculated and fit against “experimental” lines. With the help of nine independent parameters, an overall precision of 8.8 cm −1 is obtained. Vibrational intensities of the infrared active lines are given for overtones below 9000 cm −1 .
Published: 1997
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47. The H + CO ⇌ HCO reaction studied by ab initio benchmark calculations

Author: Laurent Wiesenfeld, Denis Duflot, Céline Toubin, Phillip Peters, Laboratoire de Physique des Lasers, Atomes et Molécules - UMR 8523 (PhLAM), Université de Lille-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), Physico-Chimie Moléculaire Théorique (PCMT), Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG ), Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-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), Observatoire des Sciences de l'Univers de Grenoble (OSUG), and 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)
Subjects: Davidson correction, 010304 chemical physics, Chemistry, Anharmonicity, Ab initio, General Physics and Astronomy, Configuration interaction, 010402 general chemistry, 01 natural sciences, 0104 chemical sciences, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Ab initio quantum chemistry methods, 0103 physical sciences, Density functional theory, Complete active space, Physical and Theoretical Chemistry, Atomic physics, Basis set
Abstract: International audience; : The title reaction has been calculated using complete active space self-consistent field and internally contracted multi-reference configuration interaction, including Davidson correction, calculations. Dunning's correlation consistent atomic basis sets, together with several complete basis set extrapolation schemes, were employed. Core-valence and scalar relativistic effects were also taken into account, as well as anharmonicity of the vibrational modes. Core-valence correlation appears to have a large impact on the calculated frequencies, spectroscopic constants, and on the energetics. In particular, the best estimate for the HCO (DCO) formation barrier height at 0 K, 4.54 ± 0.14 (4.43 ± 0.14) kcal mol(-1) is larger than previous theoretical works and well above the usually accepted value of 2.0 ± 0.4 kcal mol(-1), measured at room temperature. Inclusion of temperature and entropy at 298 K does not seem to be able to solve this discrepancy. The present theoretical barrier height is therefore the recommended value. The exo-ergicity of the HCO (DCO) dissociation reaction, predicted to be -13.36 ± 0.57 (-14.72 ± 0.57) kcal mol(-1), is slightly below the experimental value. Finally, all tested density functionals fail to reproduce accurately both the formation and dissociation barriers.
Published: 2013
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48. Analysis of the formation of CH+ in collision of C2+ ions with molecular hydrogen

Author: Marie-Christine Bacchus-Montabonel, Laurent Wiesenfeld, Institut Lumière Matière [Villeurbanne] (ILM), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon, Institut de Planétologie et d'Astrophysique de Grenoble (IPAG ), Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG), and 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)
Subjects: [PHYS]Physics [physics], 010308 nuclear & particles physics, Chemistry, Polyatomic ion, Hydrogen molecule, General Physics and Astronomy, Charge (physics), Collision, 01 natural sciences, Potential energy, 3. Good health, Ion, [SPI]Engineering Sciences [physics], Ab initio quantum chemistry methods, Chemical physics, 0103 physical sciences, [CHIM]Chemical Sciences, Physical and Theoretical Chemistry, Atomic physics, 010303 astronomy & astrophysics
Abstract: International audience; A theoretical treatment of the different processes involved in the collision of C2+ ions with molecular hydrogen is developed with consideration of charge transfer and formation of the CH+ molecular ion. Calculations of the potential energy surfaces and couplings are performed by means of ab initio quantum chemistry methods. Analysis of the different routes is detailed.
Published: 2013
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49. Spin-orbit quenching of the C + ( 2 P ) ion by collisions with para - and ortho -H 2

Author: Alexandre Faure, Laurent Wiesenfeld, Paul J. Dagdigian, Philippe Halvick, Ghofran Werfelli, Thierry Stoecklin, François Lique, Laboratoire Ondes et Milieux Complexes (LOMC), Centre National de la Recherche Scientifique (CNRS)-Université Le Havre Normandie (ULH), Normandie Université (NU)-Normandie Université (NU), 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), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG ), Observatoire des Sciences de l'Univers de Grenoble (OSUG), and 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)
Subjects: Ions, [PHYS]Physics [physics], Astrochemistry, 010304 chemical physics, Chemistry, Interstellar cloud, Ab initio, General Physics and Astronomy, Multireference configuration interaction, 01 natural sciences, 7. Clean energy, Potential energy, Carbon, Ion, 13. Climate action, Ab initio quantum chemistry methods, 0103 physical sciences, Radiative transfer, Quantum Theory, Physical and Theoretical Chemistry, Atomic physics, 010303 astronomy & astrophysics, Hydrogen
Abstract: International audience; Spin-orbit (de-)excitation of C+(2P) by collisions with H2, a key process for astrochemistry, is investigated. Quantum-mechanical calculations of collisions between C+ ions and para- and ortho-H2 have been performed in order to determine the cross section for the C+ 2P3/2 → 2P1/2 fine-structure transition at low and intermediate energies. The calculation are based on new ab initio potential energy surfaces obtained using the multireference configuration interaction method. Corresponding rate coefficients were obtained for temperatures ranging from 5 to 500 K. These rate coefficients are compared to previous estimations, and their impact is assessed through radiative transfer computation. They are found to increase the flux of the 2P3/2 → 2P1/2 line at 158 μm by up to 30% for typical diffuse interstellar cloud conditions.
Published: 2013
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50. Rotational excitation of HDO and D2O by H2: experimental and theoretical differential cross-sections

Author: Laurent Wiesenfeld, David H. Parker, Ashim Kumar Saha, Gautam Sarma, and Chung-Hsin Yang
Subjects: Resonance-enhanced multiphoton ionization, Range (particle radiation), Scattering, Chemistry, Forward scatter, Applied Molecular Physics, General Physics and Astronomy, Inelastic scattering, Collision, 01 natural sciences, 7. Clean energy, 0103 physical sciences, Molecular and Laser Physics, Physical and Theoretical Chemistry, Atomic physics, 010306 general physics, 010303 astronomy & astrophysics, GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries), Astrophysics::Galaxy Astrophysics, Differential (mathematics), Excitation
Abstract: We present state-to-state differential cross sections (DCSs) for rotationally inelastic scattering of HDO by normal- and para-H(2) at collision energies of 580 cm(-1) and 440 cm(-1). (2+1) resonance enhanced multiphoton ionization is used to detect rotationally cold HDO molecules before collision and as scattering products, which occupy higher rotational states due to collision with H(2). Relative integral cross sections of HDO are obtained by integrating its DCSs measured at the same experimental conditions. Experimental and theoretical DCSs of HDO scattered by normal- and para-H(2) are in good agreement in 30°-180° range of scattering angles. This partial agreement shows the accuracy of the recently tested potential of H(2)O-H(2), but now by using a completely different set of rotational transitions that are (unlike in H(2)O), not forbidden by nuclear spin restrictions. Similar results are presented for D(2)O scattered by normal-H(2) at collision energy of 584 cm(-1). The agreement between experiment and theory is, however, less good for forward scattering of HDO/D(2)O. A critical analysis of this discrepancy is presented.
Published: 2013

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