A5017967480- Advanced Chemical Physics Studies
- Atomic and Molecular Physics
- Spectroscopy and Laser Applications
- Atmospheric Ozone and Climate
- Astrophysics and Star Formation Studies
- Laser-induced spectroscopy and plasma
- Astro and Planetary Science
- Solar and Space Plasma Dynamics
- Stellar, planetary, and galactic studies
- Molecular Spectroscopy and Structure
- Quantum, superfluid, helium dynamics
- Cold Atom Physics and Bose-Einstein Condensates
- Spectroscopy and Quantum Chemical Studies
- Ionosphere and magnetosphere dynamics
- Atomic and Subatomic Physics Research
- Electron and X-Ray Spectroscopy Techniques
- Mass Spectrometry Techniques and Applications
- Astronomy and Astrophysical Research
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Photochemistry and Electron Transfer Studies
- Diamond and Carbon-based Materials Research
- Laser Design and Applications
- Inorganic Fluorides and Related Compounds
- Laser-Plasma Interactions and Diagnostics
Observatoire de Paris
2010-2023
Laboratoire d’Etudes du Rayonnement et de la Matière en Astrophysique et Atmosphères
2014-2023
Sorbonne Université
2014-2023
Centre National de la Recherche Scientifique
2011-2023
Université Paris Sciences et Lettres
2015-2023
Janssen (Belgium)
2014
Janssen (France)
1976-2012
Herzberg Institute of Astrophysics
2002
University of Kentucky
2002
Georgia State University
2001
The BASECOL2012 database is a repository of collisional data and web service within the Virtual Atomic Molecular Data Centre (VAMDC, http://www.vamdc.eu). It contains rate coefficients for excitation rotational, ro-vibrational, vibrational, fine, hyperfine levels molecules by atoms, molecules, electrons, as well fine-structure some atoms that are relevant to interstellar circumstellar astrophysical applications. Submissions new published sets welcome, they will be critically evaluated before...
Mg is often traced in late-type stars using lines of neutral magnesium, which expected to be subject departures from LTE. The astrophysical importance as well its relative simplicity an atomic physics point view, makes it a prime target and test bed for detailed ab initio non-LTE modelling stellar atmospheres. For the low-lying states i, electron collision data were calculated R-matrix method. Calculations collisional broadening by hydrogen also performed where missing. These calculations,...
The influence of inelastic hydrogen atom collisions on non-LTE spectral line formation has been, and remains to be, a significant source uncertainty for stellar abundance analyses, due the difficulty in obtaining accurate data low-energy atomic either experimentally or theoretically. For lack better alternative, classical "Drawin formula" is often used. Over recent decades, our understanding these improved markedly, predominantly through number detailed quantum mechanical calculations. In...
We report full quantum scattering calculations for low-energy near-threshold inelastic cross sections in Mg + H and Mg${}^{+}$ H${}^{\ensuremath{-}}$ collisions. The include all transitions between the eight lowest adiabatic MgH(${}^{2}\phantom{\rule{-0.16em}{0ex}}{\ensuremath{\Sigma}}^{+}$) molecular states, with uppermost of those diabatically extended to ionic state asymptotic region. This allows us treat excitation processes seven atomic states magnesium collisions hydrogen atoms, as...
Context.Over the next few years, ALMA and Herschel missions will perform high spatial spectral resolution studies at infrared sub-millimeter wavelengths. Modeling of molecular emission requires excitation calculations using radiative, as well collisional rates, with most abundant species. In interstellar medium, dominant collision partner is H2, but little data available for collisions H2. If He are available, it has often been proposed to use more rate coefficients He, appropriate reduced...
Rotational excitation of the CN(X Σ2+) molecule with He is investigated. We present a new two-dimensional potential energy surface (PES) for He–CN system, calculated at an internuclear CN distance frozen its experimental equilibrium distance. This PES was obtained using open-shell, coupled-cluster method including all single and double excitations, as well perturbative contributions connected triple excitations [RCCSD(T)]. Bond functions were placed mid-distance between center mass atom...
Rate coefficients for inelastic Mg+H collisions are calculated all transitions between the lowest seven levels and ionic state (charge transfer), namely Mg(3s2 1S, 3s3p 3P, 1P, 3s4s 3S, 3s3d 1D, 3s4p 3P)+H(1s) Mg+(3s 2S)+H−. The rate based on cross-sections from full quantum scattering calculations, which themselves detailed chemical calculations MgH molecule. data needed non-LTE applications in cool astrophysical environments, especially stellar atmospheres, presented a temperature range of...
We derive a classical path expression for pressure-broadened atomic spectral line shape that allows an electric-dipole moment is dependent on the position of perturbers. The theory applied to hydrogen Lyman-$\ensuremath{\alpha}$ and Lyman-$\ensuremath{\beta}$ lines broadened by collisions with neutral ionized hydrogen. far wings Lyman series exhibit satellites, enhancements may be associated quasimolecular states ${\mathrm{H}}_{2}$ ${\mathrm{H}}_{2}^{+}$. sizes these features depend values...
Modelling of molecular emission from interstellar clouds requires the calculation rate coefficients for excitation by collisions with most abundant species. From a new, highly correlated, two-dimensional potential energy surface, rotational C2H(X2Σ+) molecule collision He is investigated. State-to-state collisional cross-sections between 25 first fine structure levels C2H are calculated energies up to 800 cm−1 which yields after thermal averaging T= 100 K. The exact spin splitting taken into...
The formulation given by Feautrier et al. (1971) for transitions induced electron impact among ground state terms of atoms with one configuration npq is used a slight modification taking into account the orthogonality free wavefunction to bound orbitals. A system coupled integro differential equations, obtained from modified close coupling expansion including long range pseudo states, solved numerically incident on oxygen in threshold region. present results agree very closely experiment....
The conical intersection regions on the potential energy functions of valence excited 1,3Σu−, 1,3Δu, 3Σu+, and 1,3Πg states CO2 have been investigated by ab initio calculations. Using large scale multireference configuration interaction ordering lowest has calculated to be 3B2, 3A2, 1A2 followed 1B2. All these bent equilibrium structures lie energetically below their dissociation asymptotes. near parts mapped in three dimensions multiconfiguration self-consistent field 1,3B2 1,3A2 differ...
view Abstract Citations (84) References (24) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Impact Line Linear Polarization as a Diagnostic of 100 keV Proton Acceleration in Solar Flares Henoux, J. C. ; Chambe, G. Smith, D. Tamres, Feautrier, N. Rovira, M. Sahal-Brechot, S. The use impact linear polarization chromospheric lines diagnostic protons is proposed. Observations hard X-ray emission are examined, noting the possibility that proton beams bombarding...
We present two new two-dimensional potential-energy surfaces for the SO-He system calculated at SO r distance frozen its experimental minimum-energy distance. Both are obtained RCCSD(T) level using different basis sets (AVTZ and AVQZ) three atoms. Bond functions placed mid-distance between center of mass He a better description van der Waals well. Close-coupling calculations collisional excitation cross sections fine-structure levels by low energies. The exact splitting is taken into...
Rotational excitation of the interstellar species SO(X3Sigma-) with H2 is investigated. The authors present a new four-dimensional potential energy surface for SO-H2 system, calculated at an internuclear SO distance frozen its experimental minimum distance. It was obtained RCCSD(T) level using aug-cc-pVTZ basis sets four atoms. Bond functions were placed mid-distance between center mass and better description van der Waals interaction. Close coupling calculations collisional cross sections...
We present collisional rate coefficients for SO2 with ortho and para molecular hydrogen the physical conditions prevailing in dark clouds. Rate first 31 rotational levels of this species (energies up to 55 K) temperatures between 5 30 K are provided. have found that these about ten times more than those previously computed helium. calculated expected emission centimeter wavelength lines SO2. find transition connecting metastable 202 level 111 one is absorption against cosmic background a...
The modelling of emission spectra molecules seen in interstellar clouds requires the knowledge collisional rate coefficients. Among commonly observed species, N2H+ is particular interest since it was shown to be a good probe physical conditions cold molecular clouds. Thus, we have calculated hyperfine-structure-resolved excitation coefficients N2H+(X1Σ+) by H2(j = 0), most abundant partner medium. calculations are based on new potential energy surface, obtained from highly correlated ab...
Full quantum scattering calculations of cross sections for low-energy near-threshold inelastic Mg+H collisions are reported, such processes being interest modelling Mg spectral lines in stellar atmospheres. The made three transitions between the ground and two lowest excited states, Mg(3s(2) (1)S(0)), Mg(3s3p (3)P) (1)P). based on adiabatic potentials nonadiabatic couplings low-lying (2)Sigma(+) first (2)Pi calculated using large active spaces basis sets. Non-adiabatic regions associated...
The accurate highly correlated ab initio calculations for ten low lying covalent Σ+2 states of CaH molecule, and one ionic Ca+H- state, are performed using large active space extended basis set, with special attention to the long-range (6-20 Å) region where a number avoided crossings between occur. These further transformed diabatic representation numerical diabatization scheme based on minimization derivative coupling. This results in smooth Hamiltonian which can be easily fit an analytic...
Aims. Inelastic processes in low-energy Ca + H and Ca+ H− collisions are treated for the states from ground state up to ionic with aim provide rate coefficients needed non-LTE modeling of cool stellar atmospheres.
Abstract Inelastic cross sections and rate coefficients in Ca + H − collisions for all transitions between the 17 lowest covalent states plus one ionic molecular state are calculated based on most recent ab initio adiabatic potentials 11 states, as well model asymptotic higher-lying including ground state. Nuclear dynamics is treated by probability-current method multichannel formulas collision energy range 0.01–100 eV. The rates computed mutual neutralization, ion-pair formation,...
Context.Over the next few years, ALMA and Herschel missions will open universe to high spatial spectral resolution studies at infrared sub-millimeter wavelengths. This allow investigators study in much greater detail composition evolution of molecules space. Modeling spectra require accurate radiative collisional rates species astrophysical interest.Aims.We calculate new coefficients for 91 first rotational levels SO molecule collision with He temperatures ranging from 50 300...
We report a joint experimental and theoretical study that directly tests the quality of potential energy surfaces used to calculate changing cross sections water in collision with helium molecular hydrogen, at conditions relevant for astrophysics. Fully state-to-state differential are measured H2O–He H2O–H2 collisions 429 575 cm−1 energy, respectively. compare these ones H2O+H2 derived from state-of-the-art [P. Valiron et al., J. Chem. Phys. 129, 134306 (2008)] quantum scattering...
The silicon monoxide (SiO) molecule is a key species for the study of interstellar medium as it used to trace warm shocked gas. A large number transitions, including high rotational levels, are observed, and modelling these emission lines can provide valuable information on chemical physical conditions observed regions. In environments, where local thermodynamical equilibrium approximation not valid, an accurate requires collisional rate coefficients with most abundant species. We focus...