High-resolution stimulated Raman spectroscopy and analysis of the ν 1 , 2ν 1 -ν 1 , ν 2 , 2ν 2 , and 3ν 2 -ν 2 bands of CF4

The spectra of the ν1, 2ν1–ν1, ν2, 2ν2, and 3ν2–ν2 bands of CF4 were obtained with a quasi-continuous wave stimulated Raman spectrometer. These five bands were studied at a temperature of 135 and 300 K (for the hot bands). The spectrum of ν1 was obtained at a sample pressure of 2 mbar. For the spectra of the other regions, which are much weaker, higher pressures were used. The analysis has been performed thanks to the xtds and spview softwares developed in Dijon for such highly symmetric molecules. Combining the present results with a previous infrared study, we could determine a very accurate value for the C–F equilibrium bond length, i.e. re = 1.31588(6) A. Copyright © 2013 John Wiley & S…

Diode laser spectroscopy of the nu(8) band of the SF(5)Cl molecule.

Abstract Diode laser spectra of SF 5 Cl have been recorded in the ν 8 band region at a temperature of ca. 240 K, a pressure of 0.25 mbar and an instrumental bandwidth of ca. 0.001 cm −1 . Four regions have been studied: a first one in the P -branch (906.849–907.687 cm −1 ), a second one in the Q -branch (910.407–910.944 cm −1 ), and two other ones in the R -branch (913.957–914.556 and 917.853–918.705 cm −1 ). The whole ν 1 / ν 8 dyad of SF 5 35 Cl has been previously recorded in the group of Professor H. Burger in Wuppertal, thanks to a Fourier transform infrared spectrometer [J. Mol. Spectrosc. 208 (2001) 169]. These data have thus been combined with our diode laser ones in the aim of refi…

Critical proofreading of the book "Les derniers jours du siège d'Alésia"

Was there a lunar eclipse that could have influenced the outcome of the Battle of Alesia? This is the argument developed in the book by Alain Deyber and David Romeuf, «Les Derniers Jours du Siège d'Alésia». Having verified the existence of an eclipse on the date given by the authors and based on the latest publications as well as on the scientific consensus, we conduct a critical study on the chronology of the siege and on the ethnological arguments, even ethno-astronomical of the authors.

Spectroscopic factors Influencing on the Atmospheric Radiative Transfer Modeling for the Methane Total Amount Retrieval

Effect of the Zeolite Framework on Spectroscopic Properties of Ethylene: FTIR Measurements and Quantum Chemical Calculations

Intensity Analysis of the 10 Micron Band System of Ethylene

First analysis of the ν3+ν5 combination band of SF6 observed at Doppler-limited resolution and effective model for the ν3+ν5-ν5 hot band

Abstract Sulfur hexafluoride is a greenhouse gas with a long lifetime in the atmosphere and an important tracer for air mass circulation atmospheric models. The IR spectrum of this heavy species, however, features many hot bands at room temperature (at which only 30% of the molecules lie in the ground vibrational state), especially those originating from the lowest, v 6 and v 5 = 1 vibrational states. Using a cryogenic long path cell with variable optical path length and temperatures regulated between 168 and 163 K, coupled to Synchrotron Radiation and a high resolution interferometer, Doppler-limited spectra of the very weak ν 3 + ν 5 band near 1450 cm−1 have been recorded. Low temperature…

Spectroscopie à Haute Résolution de l'Adamantane C10H16

Titan's surface and atmosphere from Cassini/VIMS data with updated methane opacity

International audience; We present an analysis of Titan data acquired by the Cassini Visual and Infrared Mapping Spectrometer (VIMS), making use of recent improvements in methane spectroscopic parameters in the region 1.3-5.2 μm. We first analyzed VIMS spectra covering a 8 × 10-km2 area near the Huygens landing site in order to constrain the single scattering albedo (ω0) of the aerosols over all of the VIMS spectral range. Our aerosol model agrees with that derived from Huygens Probe Descent Imager/Spectral Radiometer (DISR) in situ measurements below 1.6 μm. At longer wavelengths, ω0 steadily decreases from 0.92 at 1.6 μm to about 0.70 at 2.5 μm and abruptly drops to about 0.50 near 2.6 μm…

High-Resolution Spectroscopy and Preliminary Analysis of the ν1/ν8 Dyad of SF535Cl

Abstract The Fourier transform infrared spectrum of monoisotopic SF 5 35 Cl has been recorded in the 650- to 960-cm −1 region at a temperature of 203 K, a pressure of 0.2 mbar, and an instrumental bandwidth of 0.002 cm −1 . The ν 1 /ν 8 dyad near 900 cm −1 has been analyzed with an effective Hamiltonian developed up to the fourth order and the help of a recently developed set of programs called C 4 v TDS ( C 4 v Top Data System, http://www.u-bourgogne.fr/LPUB/C4VTDS.html ); 1346 transitions for ν 1 , 351 transitions for ν 8 , and 406 ground state combination differences have been assigned and fitted. A global fit has been obtained with an rms of 0.00082 cm −1 for the ν 1 ( a 1 ) band, of 0.…

The SO2F2 quasi-spherical top: Correspondence between tensorial and Watson's formalisms

Abstract The SO2F2 quasi-spherical top molecule with C2v symmetry is considered as a distorted spherical top deriving from the SO 4 2 − tetrahedral ion. We present here a detailed correspondence between the tensorial formalism using the Td⊃C2v reorientation and the usual Hamiltonian of Watson. We have also performed ab initio calculations in order to determine the centrifugal distorsion constants in the vibrational ground state.

Twentieth colloquium on high resolution molecular spectroscopy - Dijon, 3 to 7 September 2007 - Foreword

International audience

Analysis of the rovibrational spectrum of 13CH4 in the Octad range

Abstract We have measured the infrared spectrum of methane 13 CH 4 from 1100 cm −1 (33 THz), below the fundamental range, to about 12 000 cm −1 (360 THz) in the high overtone region at temperatures ranging from 80 K to 300 K by high resolution Fourier transform infrared (FTIR) spectroscopy. With instrumental bandwidths between 0.0027 cm −1 (80 MHz) and 0.01 cm −1 (300 MHz) this provides close to Doppler-limited spectra, using the Zurich prototype spectrometer (ZP2001, Bruker 125HR) combined with a multipath collisional cooling cell. Using perturbation theory and an accurate empirically adjusted potential we have computed ro-vibrational energy levels of 13 CH 4 and 12 CH 4 in the same energy…

Ab Initio Calculations and High-Resolution Spectroscopy of the Bending Pentad of SiH2D2 in the 10–16 um Region

International audience; The SiH2D2 asymmetric top has nine vibrational modes, five of them forming a pentad strongly perturbed by Coriolis interactions. High-level ab initio calculations of SiH2D2 have been performed which yield numerous spectroscopic parameters related to the harmonic and anharmonic force fields. The bending pentad comprising v4(A1), v7(B1), v5(A2), v9(B2), and v3(A1) has been studied by high-resolution Fourier transform spectroscopy; the region 600 –1050 cm-1 has been investigated with a resolution of ca. 4 x 10-3 cm-1. Raman BOXCARS spectroscopy has been used for the infrared inactive v5 band. The Raman apparatus function was 0.0054 cm-1. Assignments of about 4000 transi…

Analyse Globale en Fréquences et en Intensités des Raies de 12CH4 dans la Région 0–4800 cm-1

Simulations of Titan Observations in the 1.58 Micron Transparency Window with High-Resolution, Low Temperature CRDS Spectra

MeCaSDa and ECaSDa: Methane and ethene calculated spectroscopic databases for the virtual atomic and molecular data centre

Abstract Two spectroscopic relational databases, denoted MeCaSDa and ECaSDa, have been implemented for methane and ethene, and included in VAMDC (Virtual Atomic and Molecular Data Centre, http://portal.vamdc.eu/vamdc_portal/home.seam ). These databases collect calculated spectroscopic data from the accurate analyses previously performed for the electronic ground state of methane, ethene, and some of their isotopologues: 12CH4, 13CH4, and 12C2H4. Both infrared absorption and Raman scattering lines are included. The polyad structures are reported and the transitions are precisely described by their energy, their intensity and the full description of the lower and upper states involved in the …

High-resolution FTIR spectrum and analysis of the ν2+ν4 combination band of 32SF6

Abstract The spectroscopic knowledge of sulfur hexafluoride, which is necessary for a correct remote sensing and monitoring of this species in the Earth’s atmosphere, is still very partial. In particular, the hot bands in the strongly absorbing ν 3 region (near 948 cm −1 ) have not been analyzed yet. Their study implies the analysis of many vibrational levels and thus the spectroscopy of various fundamental, harmonic, and combination bands. The present work is a new contribution to this topic, concerning the ν 2 + ν 4 combination band. The FTIR spectrum of this region has been recorded at room temperature with a resolution of 0.002 cm −1 . The data have been analyzed thanks to the HTDS soft…

Le méthane dans l'atmosphère de Titan. De la spectroscopie fondamentale à la planétologie

Le méthane (CH4) joue sur Tian, le plus gros satellite de Saturne, un rôle similaire à celui de l'eau sur Terre. Il y est de plus à l'origine d'une chimie organique complexe. La spectroscopie étant la technique privilégiée pour mesurer le CH4 dans les atmosphères planétaires, des modèles précis de l'absorption de la lumière par cette molécule doivent être développés. Les résultats récents obtenus dans ce domaine à l'Institut Carnot de Bourgogne, en collaboration étroite avec des planétologues, permettent notamment de contribuer à l'interprétation des résultats de la mission Cassini-Huygens.

Development of the Hamiltonian and transition moment operators of symmetric top molecules using the O(3)⊃C∞v⊃C3v group chain

Abstract We present a development of the Hamiltonian, dipole moment, and polarizability operators for XY3Z molecules. These rovibrational operators are written with the aid of a tensorial formalism derived from the one already used in Dijon and adapted to the XY3Z symmetric tops in a recent paper [A. El Hilali, V. Boudon, M. Loete, J. Mol. Spectrosc. 234 (2005) 166–174]. We use the O (3) ⊃ C∞v ⊃ C3v group chain. Expressions for the matrix elements are derived for these operators.

The vibrational levels of methane obtained from analyses of high-resolution spectra

International audience; Methane and its tetrahedral isotopologues are spherical-top molecules whose high-resolution rovibrational spectra can only be analyzed in detail, thanks to sophisticated symmetry-adapted tensorial models. However, the effective Hamiltonian parameters of such models do not give direct access to the positions of the vibrational sublevels. In this paper, we present a calculation of the vibrational level positions for 12CH4, 13CH4, 12CD4 and 13CD4 performed using the effective Hamiltonian parameters obtained through recent analyses. We also include the results of a re-analysis of the octad system of 12CH4 performed with a higher order of the development which slightly im…

Experimental IR Study and Ab Initio Modelling of Ethylene Adsorption in a MFI Zeolite-Type Host Zeolite

International audience

Symmetry-adapted tensorial formalism to model Rovibrational and rovibronic molecular spectra

International audience

High-Resolution Spectroscopy and Preliminary Global Analysis of C–H Stretching Vibrations of C2H4 in the 3000 and 6000 cm-1 Regions

International audience; Ethylene (ethene, H2C=CH2) is a naturally occurring compound in ambient air that affects atmospheric chemistry and global climate. The C2H4 spectrum is available in databases only for the 1000 and 3000 cm−1 ranges. In this work, the ethylene absorption spectrum was measured in the 6030- 6250 cm−1 range with the use of a high resolution Bruker IFS 125HR Fourierspectrometer and a two-channel opto-acoustic spectrometer with a diode laser. As a secondary standard of wavelengths, the methane absorption spectrum was used in both cases. A preliminary analysis was realized thanks to the tensorial formalism developed by the Dijon group that is implemented in the XTDS software…

Stark Effect Using Tensorial Formalism in the D2h Group: Application to the C2H4 Molecule

Line Positions and Intensities in the ν12 Band of Ethylene Near 1450 cm-1: An Experimental and Theoretical study

International audience

The ground state rotational spectrum of SO2F2

Abstract The analysis of the ground state rotational spectrum of SO 2 F 2 [K. Sarka, J. Demaison, L. Margules, I. Merke, N. Heineking, H. Burger, H. Ruland, J. Mol. Spectrosc. 200 (2000) 55] has been performed with the Watson’s Hamiltonian up to sextic terms but shows some limits due to the A and S reductions. Since SO 2 F 2 is a quasi-spherical top, it can also be regarded as derived from an hypothetical XY 4 molecule. Thus we have developed a new tensorial formalism in the O (3)⊃ T d ⊃ C 2 v group chain (M. Rotger, V. Boudon, M. Loete, J. Mol. Spectrosc. 216 (2002) 297]. We test it on the ground state of this molecule using the same experimental data (10 GHz–1 THz region, J up to 99). Bot…

Field-free one-dimensional alignment of ethylene molecule

International audience; We report an experimental study of non-adiabatic laser-induced molecular alignment of ethylene (C2H4) using a linearly polarized short laser pulse of moderate intensity. The information about the confinement of the C=C bond axis along the direction of the applied electric field is obtained by measuring the depolarization of a second short pulse of weak intensity interacting with the molecules after they have been exposed to the first pulse. The experimental data are compared with the numerical simulation of the Schr¨odinger equation written for the non-resonant interaction of an asymmetric top rigid rotor with a linearly polarized electric field. The field-free align…

Etat de l'Art des Analyses Raie par Raie des Spectres du Méthane

Synchrotron-based Fourier transform spectra of the ν23 and ν24 IR bands of hexamethylenetetramine C6N4H12

Abstract Hexamethylenetetramine (HMT), C6N4H12 is a spherical top with nine IR-active modes. Because of its relevance for astrophysics, we recorded the absorption spectra in the full range of its fundamental bands. In total, we detected eight fundamental bands and recently published the rotational analysis of the four most intense bands ( ν 19 , ν 20 , ν 21 , ν 22 ) located in the 1000–1500 cm−1 range as a support for astronomical searches (Pirali et al., 2014). While the CH stretch modes are unresolved broad features, in this article we report the analysis of the two remaining fundamental bands exhibiting rotationally resolved structures: ν 23 –GS and ν 24 –GS located at about 820 cm−1 and…

First High-Resolution Raman Spectrum and Analysis of the ν5 Bending Fundamental of SF6

Abstract The high-resolution Raman spectrum of the Q , R , and S branches of the ν 5 bending fundamental of SF 6 has been recorded at a temperature of 195 K (dry ice) and a pressure of 39 mbar. This is the first study ever performed of a ν 5 band of an XY 6 molecule. It has been analyzed thanks to the HTDS software ( http://www.u-bourgogne.fr/LPUB/shTDS.html ) developed in Dijon. This contribution should be of help in understanding the role hot bands in the strong absorbing ν 3 region.

Theoretical Investigation of the Energy Surface and Electric Properties of the Van der Waals Complex CH4-N2

High-Resolution Ethylene Absorption Spectrum Between 6035 and 6210 cm-1

top data system ( TDS) software for infrared spectrum simulation of asymmetric molecules: some improvements to the TDS packages

Abstract The spherical top data system (STDS) program suite developed in Dijon has been extended with the aim of studying any rovibrational band or polyad of XY 2 Z 2 ( C 2 v ) asymmetric top molecules. We work in the O ( 3 ) ⊃ T d ⊃ C 2 v chain because these species result from the substitution of two ligands of a corresponding “parent” spherical top and thus are relatively close to tetrahedral symmetry. The choice of this group chain has consequences on the method used to specify the input parameters of the programs for Hamiltonian and transition moment model calculations. One example concerning the ground state of the SO2F2 quasi-spherical molecule is presented. As before, this suite con…

The partition sum of methane at high temperature

11 pages, 4 Tables, 3 Figures Computer code on line at http://icb.u-bourgogne.fr/JSP/TIPS.jsp; International audience; The total internal partition function of methane is revisited to provide reliable values at high temperature. A multi-resolution approach is used to perform a direct summation over all the rovibrational energy levels up to the dissociation limit. A computer code is executable on line at the URL : http://icb.u-bourgogne.fr/JSP/TIPS.jsp to allow the calculation of the partition sum of methane at temperatures up to 3000 K. It also provides detailed information on the density of states in the relevant spectral ranges. The recommended values include uncertainty estimates. It is …

Spectroscopy of XY3Z (C3v) Molecules with an Even or Odd Number of Electrons: A Tensorial Formalism Adapted to the SU(2) ⊗ CI ⊃ C∞vS ⊃ C3vS Group Chain

The Pentad and the Octad of 13CH4: Lines in the 2200–4700 cm-1 Region

International audience

Infrared spectroscopy of ruthenium tetroxide and high-resolution analysis of the ν3 band

Abstract RuO 4 is a heavy tetrahedral molecule which has practical uses for several industrial fields. Due to its chemical toxicity and the radiological impact of its 103 and 106 isotopologues, the possible remote sensing of this compound in the atmosphere has renewed interest in its spectroscopic properties. New, higher resolution FTIR spectra have been recorded at room temperature, using an isotopic pure sample of 102 RuO 4 and a sample with all stable isotopes present in natural abundance. We reinvestigate here the strong ν 3 stretching fundamental region and perform new assignments and effective Hamiltonian parameter fits for the five main isotopologues ( 99 RuO 4 , 100 RuO 4 , 101 RuO …

Ab initio calculation for the CH4-N2 van der Waals complex. Polarizability and dipole moment functions: semiempirical approach

Rovibrational Phase-Space Surfaces for Analysis of ν3/2ν4 Polyad Band of CF4

Spectroscopy of XY5Z (C4v) Molecules: A Tensorial Formalism Adapted to the O(3) ⊃ Oh ⊃ C4v Chain

Abstract A tensorial formalism adapted to the case of XY 5 Z symmetric tops has been developed as an extension of the usual one for the octahedral molecules. We use the O (3) ⊃ O h ⊃ C 4 v group chain. All the coupling coefficients and formulas for the computation of matrix elements are given for this chain. Such relations are also deduced in the C 4 v group itself.

CRITICAL REVIEW OF THE ARTICLE “DE BIBRACTE À AUGUSTODUNUM : OBSERVATIONS ARCHÉOASTRONOMIQUES”

Were the towns of Bibracte and Augustodunum astronomically oriented? We study in this publication an article published in the Revue Archéologique de l'Est which puts forward the hypothesis that the Gallic town of Bibracte respects, in its main buildings, orientations corresponding to sunrise on the Romanized dates of the Celtic festivals and that the Roman city of Augustodunum is rather oriented, in its urban fabric, on sunrises at the solstice, like other Roman cities. Our study tends to invalidate these hypotheses, by re-examining the reliability of the measurements taken and the chronology of the constructions in relation to the establishment of the Julian calendar.

High-resolution stimulated Raman spectroscopy and analysis of the ν 1 band of osmium tetroxide

D.B.P. and R.Z.M. acknowledge the financial support of the Ministry of Science and Innovation through research grant no. FIS2009-08069.

The 2-μm spectroscopy of Huygens probe landing site on Titan with Very Large Telescope/Nasmyth Adaptive Optics System Near-Infrared Imager and Spectrograph

[1] Several ground-based telescopes followed the event of the Huygens probe descent through Titan's atmosphere (14 January 2005). We used the Nasmyth Adaptive Optics System Near-Infrared Imager and Spectrograph (NACO) adaptive optics system at the UT-4 of the Very Large Telescope in Chile to perform both spectroscopic and imaging measurements of Titan. We present here a selected sample of the spectra we acquired on 16 January 2005 in the K band between 2.03 and 2.40 μm. Our spectra include the Huygens landing site and surrounding dark and bright areas. We apply a radiative transfer code using new methane absorption coefficients calculated in the 2-μm region. The analysis of the data yields …

Modélisation et Base de Données du Spectre Infrarouge de l'Ethylène

Virtual Atomic and Molecular Data Center

(special issue HighRus2009). VAMDC; International audience

The hot bands of silane between 2120 and 2270cm−1

Abstract The infrared spectrum of the SiH 4 molecule has been recorded between 2040 and 2320 cm −1 using the high-resolution Fourier interferometer of the Laboratoire de Photophysique Moleculaire ( Orsay , France ). The resolution was 5.4 × 10 −3  cm −1 . In this region, many lines were previously analyzed and assigned to the ν 1 / ν 3 stretching dyad of 28 SiH 4 , 29 SiH 4 , and 30 SiH 4 molecules [J. Mol. Spectrosc. 143 (1990) 35]. However, several lines in the spectrum were not assigned. The results obtained in our previous study [J. Mol. Spectrosc. 197 (1999) 307] of the infrared spectrum of 28 SiH 4 , in the bending-stretching tetrad region at 3100 cm −1 , enabled us to assign 204 of t…

High-Resolution Spectroscopy and Structure of Osmium Tetroxide. A Benchmark Study on 192OsO4

Osmium tetroxide (OsO(4)) is a heavy tetrahedral molecule that constitutes a benchmark for quantum chemistry calculations. Its favorable spin statistics (due to the zero nuclear spin of oxygen atoms) is such that only A(1) and A(2) (T(d) symmetry) rovibrational levels are allowed, leading to a dense but quite easily resolvable spectrum. We reinvestigate here the ν(1)/ν(3) stretching fundamental (940-980 cm(-1)) dyad region and perform new assignments and effective Hamiltonian parameter fits for the main isotopologue ((192)OsO(4)). We also investigate the ν(2)/ν(4) bending fundamental dyad (300-360 cm(-1)) for the first time and perform a preliminary analysis. New experimental data have been…

Spectroscopy of XY5Z (C4v) Molecules: Development of the Hamiltonian and the Transition Moment Operators Using a Tensorial Formalism

We present a development of the Hamiltonian, dipole moment, and polarizability operators of XY(5)Z (C(4v)) molecules using a tensorial formalism derived from the one developed previously in Dijon for XY(6) molecules. These operators are involved in the calculation of the energies and intensities of rovibrational transitions and are essential for spectrum simulations. Expressions for the matrix elements are derived for all these operators. Copyright 2000 Academic Press.

Symmetry-adapted tensorial formalism to model rovibrational and rovibronic spectra of molecules pertaining to various point groups

International audience; We present a short review on the tensorial formalism developed by the Dijon group to solve molecular spectroscopy problems. This approach, originally devoted to the rovibrational spectroscopy of highly symmetrical species (spherical tops) has been recently extended in several directions: quasi-spherical tops, some symmetric and asymmetric tops, and rovibronic spectroscopy of spherical tops in a degenerate electronic state. Despite its apparent complexity (heavy notations, quite complex mathematical tools), these group theoretical tensorial methods have a great advantage of flexibility: a systematic expansion of effective terms for any rovib- rational/rovibronic probl…

Le Cycle du Méthane sur Titan

Analyse du Spectre de l'Ethylene dans la Région 800–1500 cm-1 à l'Aide du Formalisme Tensoriel : Fréquences et Intensités

Dipole Moment Surface of the van der Waals Complex CH4–N2

The interaction-induced dipole moment surface of the van der Waals CH(4)-N(2) complex has been calculated for a broad range of intermolecular separations R and configurations in the approximation of the rigid interacting molecules at the MP2 and CCSD(T) levels of theory using the correlation-consistent aug-cc-pVTZ basis set with the basis set superposition error correction. The simple model to account for the exchange effects in the range of small overlap of the electron shells of interacting molecules and the induction and dispersion interactions for large R has been suggested. This model allows describing the dipole moment of van der Waals complexes in analytical form both for large R, wh…

Simultaneous Analysis of the ν2 Raman and ν2 + ν6 Infrared Spectra of the SF6 Molecule

High-resolution Raman spectra of the nu(2) band of SF(6) have been recorded at a temperature of 195 K (dry ice) and a pressure of 39 mbar. These spectra were analyzed using a new set of programs specially written for XY(6) molecules. These programs, called HTDS (highly spherical top data system) in reference to the set of programs called STDS (spherical top data system written for XY(4) molecules) can be freely accessible through ftp (user anonymous) at jupiter.u-bourgogne.fr or on the web at the URL http://www.u-bourgogne.fr/LPUB/shTDS.html. The study of nu(2) was made using a Hamiltonian developed through the third order. Four parameters were determined. The standard deviation obtained us…

Line broadening coefficient calculations for methane perturbed by nitrogen

Abstract We report semiclassical line broadening calculations for methane perturbed by nitrogen at room temperature. For this, we have developed a symmetrized version of the Robert and Bonamy theory. The interaction potential was built from electrostatic (octopole and hexadecapole for methane, quadrupole for nitrogen) and atom–atom contributions. The relative (classical) trajectories of the molecules were computed in the frame of the usual parabolic model, through analytical formula. High orders of developments had to be used for the short range molecular interactions. As a consequence, a combination of symbolic computation and source code generation was employed to implement practical calc…

D2hTDS-ST Software for Stark Spectrum Simulation of X2Y4 Asymmetric-Top Molecules

Abstract We present the D 2 h TDS-ST ( D 2 h -Top Data System for Stark effect) program suite with the aim to simulate Stark spectra of any IR active rovibrational polyad of X 2 Y 4 ( D 2 h ) asymmetric-top molecules. D 2 h TDS-ST consists in a series of FORTRAN programs called by scripts. For calculation of Stark spectra, we obtained the expressions of the dipole moment and polarizability operators of X 2 Y 4 molecules using a tensorial formalism. For convenience, we integrated the D 2 h TDS-ST programs into the D 2 h TDS package. The D 2 h TDS suite (including the D 2 h TDS-ST programs) is freely available at the URL: http://icb.u-bourgogne.fr/OMR/SMA/SHTDS/D2HTDS.html .

Habilitation Thesis

This habilitation thesis presents a synthesis of my research activities during the last eight years. I have distinguished, one the one hand, researches concerning rovibrational spectroscopy in a singlet electronic state (Part III) and, on the other hand, those concerning rovibronic spectroscopy in a degenerate electronic state (Part IV).

Spectroscopy of X2Y4 (D2h) molecules: tensorial formalism adapted to the O(3)⊃D2h chain, Hamiltonian and transition moment operators

Abstract A tensorial formalism adapted to the case of the X2Y4 molecules with D2h symmetry has been developed in the same way as in the previous works on XY4 (Td) and XY6 (Oh) spherical tops and XY5Z (C4v) symmetric tops. Here, we use the O(3)⊃D2h group chain. All the coupling coefficients and formulas for the computation of matrix elements are given for this chain and used in the case of the Hamiltonian and transition moment operators.

Titan

The 2009 Edition of the GEISA Spectroscopic Database

The updated 2009 edition of the spectroscopic database GEISA (Gestion et Etude des Informations Spectroscopiques Atmosphériques; Management and Study of Atmospheric Spectroscopic Information) is described in this paper. GEISA is a computer-accessible system comprising three independent sub-databases devoted, respectively, to: line parameters, infrared and ultraviolet/visible absorption cross-sections, microphysical and optical properties of atmospheric aerosols. In this edition, 50 molecules are involved in the line parameters sub-database, including 111 isotopologues, for a total of 3,807,997 entries, in the spectral range from 10-6 to 35,877.031cm-1.The successful performances of the new …

High-resolution Raman spectroscopy of the ν1 region and Raman-Raman double resonance spectroscopy of the 2ν1-ν 1 band of 32SF6 and 34SF 6. Determination of the equilibrium bond length of sulfur hexafluoride

The ν1 region of 32SF6 and 34SF6 has been studied by stimulated Raman spectroscopy. For both isotopomers, a detailed analysis has been performed. Several hot bands (ν1+ν6-ν6, ν1+2ν 6-2ν6, ν1+ν5-ν 5) have been taken into account to calculate synthetic spectra that satisfactorily reproduce the experimental data. These results, together with the previous studies of the other fundamental bands have allowed us to determine the equilibrium bond length of sulfur hexafluoride as r e=1.5560(1) Å, in very good agreement with recent ab initio calculations. The 2ν1-ν1 band has also been studied for both isotopomers by Raman-Raman double resonance spectroscopy and the resulting spectra have been analyze…

Spectroscopie des hexafluorures à nombre impair d'électrons

From a theoretical point of view, a tensorial formalism adapted to the study of molecules or octahedral ions with a half-integer angular momentum has been developed for the first time. We have used here the method of projective representations, more consistent than that of double groups. A complete set of coupling coefficients and formulas, as well as the corresponding computing programs have been elaborated. This has firstly allowed to write a simple model describing the vibronic structure of colored hexafluorides. Then, somme applications of this formalism to the study of rovibronic couplings of XY6 molecules in a fourfold degenerate electronic state have been considered, especially conce…

Analysis of the Spectrum of Ethylene in the 800–1500 cm-1 Region Using Tensorial Formalism: Frequencies and Intensities

Alignement moléculaire sous impulsions laser ultracourtes

Talk given by O. Faucher; National audience

Virtual atomic and molecular data centre

The Virtual Atomic and Molecular Data Centre (VAMDC, http://www.vamdc.eu) is a European Union funded collaboration between groups involved in the generation, evaluation, and use of atomic and molecular data. VAMDC aims to build a secure, documented, flexible and interoperable e-science environment-based interface to existing atomic and molecular data. The project will cover establishing the core consortium, the development and deployment of the infrastructure and the development of interfaces to the existing atomic and molecular databases. It will also provide a forum for training potential users and dissemination of expertise worldwide. This review describes the scope of the VAMDC project;…

Spectroscopic tools for remote sensing of greenhouse gases CH4, CF4 and SF6

International audience; Highly symmetrical molecules such as CH4, CF4 or SF6 are known to be atmospheric pollutants and greenhouse gases. High-resolution spectroscopy in the infrared is particularly suitable for the monitoring of gas concentration and radiative transfers in the earth's atmosphere. This technique requires extensive theoretical studies for the modeling of the spectra of such molecules (positions, intensities and shapes of absorption lines). Here, we have developed powerful tools for the analysis and the simulation of absorption spectra of highly symmetrical molecules. These tools have been implemented in the spherical top data system (STDS) and highly-spherical top data syste…

High-resolution spectroscopy and analysis of the stretching dyad of osmium tetroxide

Abstract OsO4 is a heavy tetrahedral molecule that may constitute a benchmark for quantum chemistry calculations. Its favorable spin statistics (due to the zero nuclear spin of oxygen atoms) is such that only A1 and A2 rovibrational levels are allowed, leading to a dense, but quite easily resolved spectrum. Most lines are single ones, instead of complex line clusters as in the case of other heavy spherical-tops like SF6, for instance. It is thus possible to fully assign and fit the spectrum and to obtain precise experimental effective molecular parameters. The strong ν 3 stretching fundamental has been studied a long time ago as an isolated band [McDowell RS, Radziemski LJ, Flicker H, Galbr…

Theoretical investigation of the potential energy surface of the van der Waals complex CH4-N-2

International audience; The interaction potential energy surface of the van der Waals CH4-N-2 complex has been calculated for a broad range of intermolecular separations and configurations in the approximation of rigid interacting molecules at the CCSD(T) and MP2 levels of theory using the correlation consistent aug-cc-pVTZ basis set. The BSSE correction was taken into account for all the calculations. The most stable configurations of the complex were found. Binding energies were calculated in the CBS limit with accounting for the molecular deformations. The harmonic and anharmonic fundamental vibrational frequencies and rotational constants for the ground and first excited vibrational sta…

Study of the Fundamental Bands of 70GeD4 by High-Resolution Raman and Infrared Spectroscopy: First Experimental Determination of the Equilibrium Bond Length of Germane

Abstract The four fundamental bands of 70 GeD 4 have been analyzed using the STDS software developed in Dijon (http://www.u-bourgogne.fr/LPUB/sTDS.html). Both infrared and Raman spectra were used to observe all fundamental bands. Infrared spectra of monoisotopic 70 GeD 4 were recorded in the regions 600 and 1500 cm −1 using the Bruker 120HR interferometer at Wuppertal. The resolution (1/maximum optical path difference) was between 2.3 and 3.3×10 −3 cm −1 for the ν 3 and ν 4 infrared-active fundamental bands as well as for the interacting ν 2 band. A high-resolution stimulated Raman spectrum of the ν 1 band has been recorded in Madrid. The instrumental resolution of the Raman spectrum was 3.…

Self and N2 Collisional Broadening of Methane in the THz Region Measured at the SOLEIL Synchrotron

Deformation of sulfur hexafluoride and floppiness of trifluoromethyl sulfur pentafluoride

International audience; With recent advances in space exploration and atmospheric chemistry there is an increased need for more spectroscopic tools to allow the of study complex species. One such tool is the theory of frame transformation of coupled rotor systems. In this article, the theory of frame transformation along with the concept of rotational energy surface is used to study the symmetry that occurs in trifluoromethyl sulfur pentafluoride due to the internal rotation of the CF3 radical and, more generally, to the extent of floppiness of SF5CF3. Other lower symmetries when a CF4 molecule is stuck on the various symmetry axes of an SF6 molecule are also discussed.

Corrigendum to "Titan's surface and atmosphere from Cassini/VIMS data with updated methane opacity" [Icarus 226 (2013) 470-486]

0019-1035/$ see front matter 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.icarus.2013.07.015 DOI of original article: http://dx.doi.org/10.1016/j.icarus.2013.05.033 ⇑ Corresponding author. Address: LESIA, Observatoire de Paris, Section de Meudon, 92195 Meudon Cedex, France. Fax: +33 145072806. E-mail address: bruno.bezard@obspm.fr (B. Bezard). 1 Present address: Foundation ‘‘La main a la pâte’’, Montrouge, France. M. Hirtzig , B. Bezard a,⇑, E. Lellouch , A. Coustenis , C. de Bergh , P. Drossart , A. Campargue , V. Boudon , V. Tyuterev , P. Rannou , T. Cours , S. Kassi , A. Nikitin , D. Mondelain , S. Rodriguez , S. Le Mouelic g

Spectroscopie haute température pour Jupiter chauds

National audience

Observation and analysis of the SF6 ν2+ν4−ν5 band: Improved parameters for the v5= 1 state

Abstract In this paper, we present the high resolution analysis of the weak ν 2 + ν 4 - ν 5 band of SF6 around 735 cm−1. The spectra were recorded on the AILES Beamline at the SOLEIL Synchrotron facility using a cryogenic multipass cell coupled to a Bruker 125HR spectrometer with a maximum resolution of 0.00102 cm−1. For this band, we worked with 4 mbar of SF6 at a temperature of 223 ± 2  K. The optical path length was fixed to 141 m and the spectrum recorded with 0.001 cm−1 of resolution. A new, cold spectrum of the ν 2 + ν 4 band was also collected at 153 K, 15-m path length, and 0.0015 cm−1 resolution. The analysis was performed by using the Dijon group XTDS and SPVIEW software, based on…

Titan's surface albedo variations over a Titan season from near-infrared CFHT/FTS spectra

International audience; We have observed Titan in a series of campaigns from 1991 to 1996 with the Fourier Transform Spectrometer on the CFH telescope. The data acquired provide a lightcurve from the geometric albedos in the 0.9–View the MathML source spectral region. The 1991–1993 data were previously analyzed in Coustenis et al. [1995. Titan's surface: composition and variability from its near-infrared albedo. Icarus 118, 87–104] with a spherical particle code by McKay et al. [1989. The thermal structure of Titan's atmosphere. Icarus 80, 23–53]. We present here three new datasets from the 1994, 1995 and 1996 observations, with additional information from the 0.94-μm methane window on Tita…

High-resolution spectroscopy and analysis of the V2 + V3 combination band of SF6 in a supersonic jet expansion

International audience; Sulphur hexafluoride is a very strong greenhouse gas whose concentration is increasing in the atmosphere. It is detected through infrared absorption spectroscopy in the strong ν3 fundamental region. Due to the existence of low-lying vibrational states of this molecule, however, many hot bands arise at room temperature and those are still not known. We present here a contribution to the elucidation of this hot band structure, by analysing the ν2 + ν3 combination band. We use a supersonic jet expansion high-resolution spectrum at a rotational temperature of ca. 25 K that was recorded thanks to the Jet-AILES setup at the Source Optimisée de Lumière d'Energie Intermédiai…

Infrared Spectroscopy of Small Diamondoids. Analysis of the High Rsolution Spectrum of Adamantane C10H16

High-Resolution Jet-Cooled Spectroscopy of SF6: The ν2+ ν6Combination Band of32SF6and the ν3Band of the Rare Isotopomers

The Fourier transform infrared spectrum of SF6 was recorded in a supersonic expansion jet of an SF6/argon mixture. The SF6:Ar seeding ratio was 2:3. The instrumental bandwidth was 0.005 cm-1. A globar source and an MCT detector were used. A rotational temperature of approximately 30 K was achieved. The nu2 + nu6 combination band of 32SF6 was analyzed using a modified version of the spherical top data system (STDS) programs developed in Dijon. A very good fit was obtained for this band with an rms of 0.0036 cm-1. The effective Hamiltonian was developed up to fourth order for the nu2 + nu6 part, to second order for the nu2 and ground state parts, and to first order for the nu6 part. Five hund…

Critical reading of some papers related to the Bibracte basin

Since its discovery in 1987, the monumental basin of Bibracte questions archeologists because of its atypical orientation that was thought not to follow the way on which it lies. We study 4 archeoastronomical papers dealing with the orientation of the short and long axes on the sun rise at winter solstice or on peculiar stars and we discuss the validity of these hypotheses.

Methane in Titan's atmosphere: from fundamental spectroscopy to planetology

The methane molecule (CH4) is relatively abundant in the Universe and in particular in our Solar System. On Earth, it is the main compound of natural gas and is also the second greenhouse gas of anthropic origin. On Saturn's satellite Titan it plays a role similar to water on Earth and leads to a complex chemistry.

Le méthane dans l’atmosphère de Titan - De la spectroscopie fondamentale à la planétologie

Le methane (CH4) joue sur Tian, le plus gros satellite de Saturne, un role similaire a celui de l'eau sur Terre. Il y est de plus a l'origine d'une chimie organique complexe. La spectroscopie etant la technique privilegiee pour mesurer le CH4 dans les atmospheres planetaires, des modeles precis de l'absorption de la lumiere par cette molecule doivent etre developpes. Les resultats recents obtenus dans ce domaine a l'Institut Carnot de Bourgogne, en collaboration etroite avec des planetologues, permettent notamment de contribuer a l'interpretation des resultats de la mission Cassini-Huygens.

Performance of the AILES THz-Infrared Beamline on SOLEIL for High Resolution Spectroscopy

High-Resolution Spectroscopy and Analysis of the nu(4) Bending Region of SF(6) near 615 cm(-1).

The high-resolution Fourier transform spectrum of the nu(4) bending region of SF(6) near 615 cm(-1) has been recorded at 213 K. We were able to perform a simultaneous analysis of the nu(4) and nu(4) + nu(6) - nu(6) bands of the main isotopomer, namely (32)SF(6). This is the first detailed analysis of a hot band for this molecule. The nu(4) band of (34)SF(6) was also analyzed and the Q branch of the nu(4) band of (33)SF(6) was identified. In both cases we used the HTDS software developed in Dijon. Copyright 2001 Academic Press.

Constraints on the Volatile Enrichments in HD189733b from Internal Structure Models

International audience

Titan's 3-micron spectral region from ISO high-resolution spectroscopy

Abstract The near-infrared spectrum of Titan, Saturn's largest moon and one of the Cassini/Huygens' space mission primary targets, covers the 0.8 to 5 micron region in which it shows several weak CH 4 absorption regions, and in particular one centered near 2.75 micron. Due to the interference of telluric absorption, only part of this window region (2.9–3.1 μm) has previously been observed from the ground [Noll, K.S., Geballe, T.R., Knacke, R., Pendleton, F., Yvonne, J., 1996. Icarus 124, 625–631; Griffith, C.A., Owen, T., Miller, G.A., Geballe, T., 1998. Nature 395, 575–578; Griffith, C.A., Owen, T., Geballe, T.R., Rayner, J., Rannou, P., 2003. Science 300, 628–630; Geballe, T.R., Kim, S.J.…

Applications of a New Methane Linelist to the Modeling of Titan's Spectrum in the 1.58 Micron Window

International audience

Stark Spectrum Simulation of X2Y4 Asymmetric Molecules: Application to Ethylene in a MFI-Type Host Zeolithe

Corrigendum to “Global frequency and intensity analysis of the ν10/ν7/ν4/ν12 band system of 12C2H4 at 10 μm using the D2h top data system” [J. Quant. Spectrosc. Radiat. Transf. 182 (2016) 158–171]

Abstract This corrigendum provides a new version of one of the 3 supplementary data files associated with the article A. Alkadrou et al., J. Quant. Spectrosc. Radiat. Transf. 182 (2016) 158–171, namely the HITRAN-formatted linelist generated as described in section 5 of the article. Indeed, the K a and K c labels of the upper levels of a number of transitions belonging to the ν 10 , ν 7 and ν 4 bands listed in this supplementary data file were found to be incorrect. The linelist provided with this corrigendum corrects these erroneous assignments, and provides K a and K c labels for all the upper levels.

Highly-spherical Top Data System (HTDS) software for spectrum simulation of octahedral XY6 molecules

Abstract The Spherical Top Data System (STDS) program suite developed in Dijon has been extended into two directions. First, the vibrational extrapolation is now possible for any kind of polyad scheme, this one being fully specified in the input parameters of the programs for hamiltonian and transition moment model calculations. This was not the case of the preceding version which was based on the polyad scheme of methane. Secondly, it is now possible to study any band and polyad of XY 6 molecule for which a complete treatment in the O h group is made. Up to now, only some vibrational levels of these molecules ( F 1u levels in particular) could be studied using equivalences with the T d gro…

Recent Applications and Future Prospects of Methane Spectroscopy to the Atmosphere of Titan

Self-broadening coefficients and improved line intensities for the ν7 band of ethylene near 10.5μm, and impact on ethylene retrievals from Jungfraujoch solar spectra

Relying on high-resolution Fourier transform infrared (FTIR) spectra, the present work involved extensive measurements of individual line intensities and self-broadening coefficients for the ν7 band of 12C2H4. The measured self-broadening coefficients exhibit a dependence on both J and Ka. Compared to the corresponding information available in the latest edition of the HITRAN spectroscopic database, the measured line intensities were found to be higher by about 10% for high J lines in the P branch and lower by about 5% for high J lines of the R branch, varying between these two limits roughly linearly with the line positions. The impact of the presently measured line intensities on retrieva…

High-resolution spectroscopy of difference and combination bands of SF6 to elucidate the ν3 + ν1 − ν1 and ν3 + ν2 − ν2 hot band structures in the ν3 region

The strong infrared absorption in the ν3 S–F stretching region of sulphur hexafluoride (SF6) near 948 cm−1 makes it a powerful greenhouse gas. Although its present concentration in the atmosphere is very low, it is increasing rapidly, due to industrial pollution. The ground state population of this heavy species is only 32% at room temperature and thus many hot bands are present. Consequently, a reliable remote-sensing spectroscopic detection and monitoring of this species require an accurate modelling of these hot bands. We used two experimental set-ups at the SOLEIL French synchrotron facility to record some difference and combination bands of SF6: (1) a new cryogenic multiple pass cell w…

C3v Top Data System (C3vTDS) software for spectrum simulation of XY3Z symmetric-top molecules using the group chain

Abstract The C3v Top Data System (C3vTDS) program suite has been developed with the aim of studying any rovibrational band or polyad of XY3Z (C3v) symmetric-tops molecules in a singlet electronic state. It is developed in the same way as similar programs for various molecular symmetries (Td, Oh, C4v, C2v and D2h). We work in the O ( 3 ) ⊃ C ∞ v ⊃ C 3 v group chain and this choice has consequences on the method used to specify the input parameters for Hamiltonian and transition moment calculations. One example concerning the ν 2 band of the CH 3 12 D symmetric-top molecule is presented. This package consists in a series of FORTRAN programs called by scripts. The whole package is freely acces…

Analysis of the "Unusual" Vibrational Components of Triply Degenerate Vibrational Mode nu(6) of Mo(CO)(6) Based on the Classical Interpretation of the Effective Rotation-Vibration Hamiltonian.

Rotational structure of the triply degenerate vibrational state nu(6)(F(1u)) of the octahedral molecule Mo(CO)(6) is analyzed qualitatively on the basis of classical mechanics. We show that the energy level redistribution between the vibrational components of nu(6)(F(1u)) occurs due to rotational excitation and is related to the formation of singular points of classical rotational energy surfaces. The singularity is stable under small variations of parameters of the effective rovibrational Hamiltonian. Parameters responsible for the persistence of this phenomenon are specified. Comparison with quantum calculations demonstrates the high qualitative and quantitative accuracy of our classical …

Analytical measurements of fission products during a severe nuclear accident

The Fukushima accident emphasized the fact that ways to monitor in real time the evolution of a nuclear reactor during a severe accident remain to be developed. No fission products were monitored during twelve days; only dose rates were measured, which is not sufficient to carry out an online diagnosis of the event. The first measurements were announced with little reliability for low volatile fission products. In order to improve the safety of nuclear plants and minimize the industrial, ecological and health consequences of a severe accident, it is necessary to develop new reliable measurement systems, operating at the earliest and closest to the emission source of fission products. Throug…

Simulation du Spectre Stark des Molécules X2Y4 : Application à l'Ethylène dans les Zéolithes

High Enthalpy Source dedicated to quantitative infrared emission spectroscopy of gases at elevated temperatures

International audience

Self- and air-broadened line shapes in the 2ν3 P and R branches of 12CH4

Abstract In this paper we report line shape parameters of 12 CH 4 for several hundred 2ν 3 transitions in the spectral regions 5891–5996 cm −1 (P branch) and 6015–6115 cm −1 (R branch). Air- and self-broadening coefficients were measured as a function of temperature; line mixing via off-diagonal relaxation matrix element coefficients was also obtained for 47 transition pairs. In total, nearly 1517 positions and intensities were retrieved, but many transitions were too weak for the line shape study. For this analysis, we used 25 high-resolution (0.0056 and 0.0067 cm −1 ) and high signal-to-noise (S/N) spectra of high-purity 12 CH 4 and the same high-purity 12 CH 4 broadened by dry air record…

The bending triad of the quasi-spherical top molecule SO2F2 in the 550 cm(-1) region

International audience; The analysis of the v(3)/v(7)/v(9) bending triad of SO2F2 has been recently performed with the Watson's Hamiltonian up to octic terms employing 79 rovibrational parameters but including only the first order Coriolis interaction terms, fixed to ab initio values [H. Burger, J. Demaison, F. Hegelund, L. Margules, I. Merke, J. Mol. Struct. 612 (2002) 133-141]. Since SO2F2 is a quasi-spherical top, it can also be considered as derived from the SO42- sulfate ion. We have thus developed a new tensorial formalism in the O(3) > Td > C2v group chain [M. Rotger, V. Boudon, M. Loete, J. Mol. Spectrosc. 216 (2002) 297-307]. This approach allows a systematic development of rovibra…

Weakly Bound van der Waals Complex CH4–N2: Structure, Stability, Static Polarisability

EXO-PLANETARY HIGH-TEMPERATURE HYDROCARBONS BY EMISSION AND ABSORPTION SPECTROSCOPY (e-PYTHEAS PROJECT)

International audience; e-PYTHEAS is a multidisciplinary project which combines theoretical and experimental work with exoplanet modelling applications. It sits on the frontier between molecular physics, theoretical chemistry and astrophysics. It aims at enhancing our understanding of the radiative properties of hot gaseous media to allow for improved analysis and interpretation of the large mass of data available on the thousands of exoplanets and exoplanetary systems known to date. Our approach is to use theoretical research validated by laboratory experiments and to then inject it into models of the atmospheres of the giant gaseous planets in the solar system and other planetary systems.…

XTDS and SPVIEW: Graphical tools for the analysis and simulation of high-resolution molecular spectra

International audience; XTDS is a Java front-end to the different programs implementing the tensorial formalism developed in the Dijon group [see for instance: V. Boudon, J.-P. Champion, T. Gabard, M. Loëte, F. Michelot, G. Pierre, M. Rotger, Ch. Wenger, M. Rey, J. Mol. Spectrosc. 228 (2004) 620–634 ]. It allows the simulation and analysis of polyad systems for molecules of various symmetries (Td and Oh spherical tops like CH4 and SF6, C2v and C4v quasi-spherical tops like SO2F2 and SF5Cl, D2h molecules like C2H4). SPVIEW is a multiplatform Java application that allows graphical assignment of high-resolution molecular spectra. It is possible to load, display and manipulate experimental and …

Tensorial development of the rovibronic Hamiltonian and transition moment operators for octahedral molecules

Abstract We present a development of the Hamiltonian, dipole moment and polarizability operators of octahedral XY 6 molecules in a degenerate electronic state. These rovibronic operators are written with the aid of a tensorial formalism derived from the one already used in Dijon in the case of molecules in a non-degenerate electronic state. Electronic operators are defined from the group theory properties. Transition moment operators are introduced in order to consider rovibronic transitions. Spectrum simulations are made thanks to a new version of the HTDS sofware [J. Quant. Spectrosc. Radiat. Transfer 66 (2000) 16] used for the calculation of rovibrational spectra.

Self and N-2 collisional broadening of far-infrared methane lines measured at the SOLEIL synchrotron

International audience; Following our recent study devoted to measurements of intensities of pure rotation lines of methane, room temperature far infrared spectra of methane diluted in nitrogen at five total pressures between 100 and 800 hPa have been recorded at the AILES beamline of the SOLEIL synchrotron. One hundred and five N-2 broadening coefficients of methane pure rotation lines have been measured in the 83-261 cm(-1) spectral range using multi-spectrum non-linear least squares fitting of Voigt profiles. Pressure-induced line shifts were not needed to fit the spectra to the noise level and line mixing effects were neglected. One hundred and seventy-six self broadening coefficients h…

Global Analysis of CH4 Lines in the 0–3200 cm-1 Region

International audience

13CH4 in the 2200–4700 cm-1 Region The Pentad and the Octad

High-resolution spectroscopy of the ν3 band of WF6 and ReF6 in a supersonic jet

We have recorded the Fourier-transform infrared (FTIR) spectrum of the ν3 fundamental band of WF6 in a continuous supersonic jet expansion with an instrumental bandwidth of 0.0024 cm−1 (FWHM, full width at half maximum, unapodized), using a Bomem DA.002 spectrometer. Some parts of this band have also been recorded with 0.0007 cm−1 bandwidth using a diode laser spectrometer combined with a pulsed slit jet expansion. A multiple-pass arrangement has been used for the slit jet to observe low-intensity lines. In each case, we have used a WF6:He mixture with a seeding ratio 1:3 leading to a rotational temperature of ca. 50 K. This work extends the previous investigation of Takami and Kuze [J. Che…

Theory of the rovibronic spectra of symmetric top molecules. Application to CH3O and CH3S

Poster

Infrared Spectroscopy of Molecules Trapped in Zeolites

A Tensorial Formalism Adapted to the Rovibronic Couplings in the Colored Hexafluorides: Application to the nu(5)(F(2g)) and nu(3)(F(1u)) Modes.

A tensorial formalism adapted to the case of transition-metal hexafluorides in a degenerate electronic state has been developed on the basis of preceding works about spherical-top molecules in a nondegenerate electronic state. We have introduced electronic operators constructed using group theory features and some physical considerations. Vibronic couplings (Jahn-Teller effect, etc.) have been reviewed for the triply degenerate vibrational modes nu(5)(F(2g)) and nu(3)(F(1u)) leading to the identification of the main vibronic parameters. For the first time, an effective rovibronic Hamiltonian as well as the effective transition moment operators (dipole moment and polarizability) for rovibron…

Global Frequency and Infrared Intensity Analysis of 12CH4 Lines in the 900–4800 cm-1 Region

C4v Top Data System (C4v TDS) software for infrared spectrum simulation of XY5Z symmetric molecules

Abstract The Highly spherical Top Data System program suite developed in Dijon has been extended in the aim of studying any rovibrational band or polyad of XY5Z (C4v) symmetric top molecules. We work in the O(3)⊃Oh⊃C4v chain because most of these species result from the substitution of one ligand of the corresponding spherical tops and thus are relatively close to octahedral symmetry. The choice of this group chain has consequences in the way in which it is used to specify the input parameters of the programs for Hamiltonian and transition moment model calculations. One example concerning the ν1/ν8 dyad of the SF 5 35 Cl molecule is presented. As before, this suite consists of a series of F…

22nd Colloquium on High Resolution Molecular Spectroscopy: Special Issue dedicated to Gianfranco Di Lonardo

This issue, together with a second issue to appear in early 2012, consists of contributions submitted by participants attending the Colloquium on High Resolution Molecular Spectroscopy (HRMS), held in Dijon, France from 29 August to 2 September 2011. This is the 22nd in a biannual series of international conferences, which in recent years have taken place alternately in Dijon, France (1999, 2003, 2007, 2011) and in another European Country (1997 in Glasgow, Scotland; 2001 in Nijmegen, The Netherlands; 2005 in Salamanca, Spain, 2009 in Castellammare di Stabia, Italy). This series has a longstanding tradition as one of the most important conferences worldwide on all aspects of high resolution…

Spectroscopy of XY3Z (C3v) molecules: A tensorial formalism adapted to the O(3)⊃C∞v⊃C3v group chain

Abstract A tensorial formalism adapted to the case of XY3Z symmetric tops has been developed. We use the O (3) ⊃ C∞v ⊃ C3v group chain. All the coupling coefficients and formulas for the computation of the matrix elements are given for this chain. Such relations are also deduced in C3v group itself.

High resolution Fourier transform infrared spectroscopy and analysis of the ν 6 band of jet-cooled Mo(CO) 6

Abstract Rovibrational FTIR spectra of Mo(CO) 6 have been recorded in supersonic argon expansions at 0.004 cm −1 resolution. Rotational constants have been determined for the ν 6 fundamental band of Mo( 12 CO) 6 and for the parallel band of the symmetric top isotopomer Mo( 13 CO)( 12 CO) 5 . From these results, a precise estimate of the Coriolis parameter for the ν 6 band of the main isotopomer Mo( 12 CO) 6 is derived, necessary for the analysis of the ν 6 spectrum. The observation of an octahedral splitting clearly resolved for the highest J-lines in the R branch prompted the use of a specific treatment based on the tensorial formalism developed by J.P. Champion, M. Loete, G. Pierre (Spher…

Rotational-vibrational relative equilibria and the structure of quantum energy spectrum of the tetrahedral molecule P4

We find relative equilibria (RE) of the rotating and vibrating tetrahedral molecule P4 and study the correspondence of these RE's to the extremal quantum states in the vibration-rotation multiplet and to the extrema of the semi-quantum rotational energy surfaces obtained for a number of excited vibrational states. To compute the energy of RE's we normalize the full rotation-vibration Hamiltonian H of P4 in the approximation of nonresonant modes ν E 2 and ν F_2 3 and find the stationary points of the resulting normal form (known as reduced effective Hamiltonian H eff ) which is defined on the reduced phase space CP 2 × CP 1 × S 2 . Most of these points are fixed points of the symmetry group …

Spontaneous Raman Scattering Spectrum of Gaseous IrF6 in the Ground Electronic State

First Applications of New Methane Linelists to the Modelling of Titan's Spectrum in the 1.58 and 1.28 Micron Windows

Spectroscopy of Hexafluorides with an Odd Number of Electrons: The Vibronic Bands of IrF6

Abstract The low resolution absorption spectroscopy of the first five excited electronic states of IrF 6 has made possible some new assignments for the vibronic transitions of this molecule, and the determination of new vibronic parameter values. They are more accurate than those found in the literature. In this aim, we introduce a simplified tensorial formulation for the linear Jahn–Teller terms in a fourfold degenerate electronic state of an XY 6 -type molecule, which allows easier computation of matrix elements and avoids the use of perturbation theory. Methods for IrF 6 synthesis (using a dynamical flow system) and purification are also presented.

Femtosecond Raman Spectroscopy of C2H4 and CH4 molecules

Strong thermal nonequilibrium in hypersonic CO and CH4 probed by CRDS

A new experimental setup coupling a High Enthalpy Source (HES) reaching 2000 K to a cw-cavity ring-down spectrometer has been developed to investigate rotationally cold hot bands of polyatomic molecules in the [1.5, 1.7] μm region. The rotational and vibrational molecular degrees of freedom are strongly decoupled in the hypersonic expansion produced by the HES and probed by cavity ring-down spectroscopy. Carbon monoxide has been used as a first test molecule to validate the experimental approach. Its expansion in argon led to rotational and vibrational temperatures of 6.7 ± 0.8 K and 2006 ± 476 K, respectively. The tetradecad polyad of methane (1.67 μm) was investigated under similar condit…

High-resolution spectroscopy and preliminary global analysis of C–H stretching vibrations of C2H4 in the 3000 and 6000cm−1 regions

Abstract Ethylene (ethene, H2C=CH2) is a naturally occurring compound in ambient air that affects atmospheric chemistry and global climate. The C2H4 spectrum is available in databases only for the 1000 and 3000 cm−1 ranges. In this work, the ethylene absorption spectrum was measured in the 6030–6250 cm−1 range with the use of a high resolution Bruker IFS 125HR Fourier-spectrometer and a two-channel opto-acoustic spectrometer with a diode laser. As a secondary standard of wavelengths, the methane absorption spectrum was used in both cases. A preliminary analysis was realized thanks to the tensorial formalism developed by the Dijon group that is implemented in the XTDS software package [39] .…

Tensorial Development of the Rovibronic Hamiltonian and Dipole Moment Operators for XY3Z Molecules with a Degenerate Electronic State. Preliminary Application to the CH3O Radical

Abstract We present a development of the Hamiltonian and transition moment operators of XY3Z ( C 3 v ) symmetric tops molecules in a degenerate electronic state with the aid of a tensorial formalism developed in a recent paper [A. El Hilali, V. Boudon, M. Loete, J. Mol. Spectrosc. 239 (2006) 41–50]. Electronic operators are defined from group theory properties. They provide a new approach to build an effective rovibronic Hamiltonian as well as an effective dipole moment operator for rovibronic transition of XY3Z molecules. This model is studied qualitatively thanks to the tensorial algebra properties. Expressions of the matrix elements are derived for these operators. A first simple applica…

High-Resolution Stimulated Raman Spectroscopy and Analysis of the ν1 Stretching Band of GeD4

The high-resolution stimulated Raman spectrum of the ν1 band of GeD4 with natural isotopic abundance germanium has been recorded. It has been analyzed as part of the ν1/ν3 stretching dyad. The ν1 and ν3 band centers have been deduced for all the isotopologues. Copyright © 2006 John Wiley & Sons, Ltd.

Su(4) approach to fourfold degenerate electronic states of some hexafluoride molecules

Abstract We show that two appropriate realizations of the su (4) algebra allow the construction of all electronic operators needed for the study of vibronic and rovibronic interactions in a G ′ electronic state. In each case a full bosonic realization is made and all matrix elements are calculated. Illustrations of our formalism and comparisons with previous approaches are made in the case of ν 5 ( F 2 g ) and ν 3 ( F 1 u ) modes.

Spectroscopy of XY3Z (C3v) radicals with an odd number of electrons: A tensorial formalism adapted to the group chain

Abstract A tensorial formalism adapted to the case of XY 3 Z symmetric tops with half integer angular momenta is proposed as an extension of the formalism for the group chain O  (3) ⊃  C ∞ v  ⊃  C 3 v developed in a recent paper [A. El Hilali, V. Boudon, M. Loete, J. Mol. Spectrosc. 234 (2005) 113–121]. We use the chain SU ( 2 ) ⊗ C I ⊃ C ∞ v S ⊃ C 3 v S , where G S ( G being C ∞ v or C 3 v ) is the G point group with its spinorial representations. Coupling coefficients and formulas for the computation of matrix elements of the tensor operators are derived for this chain. A deduction of coupling coefficients (Clebsch-Gordan, 6 C , 9 C , …) and similar formulas is proposed for the group C 3 …

Development of the Dipole Moment and Polarizability Operators of Octahedral Molecules

We present a development of the dipole moment and polarizability operators of octahedral molecules, using a tensorial formalism analogous to the one developed for tetrahedral molecules. These operators are involved in the calculation of the intensities of rovibrational transitions as well as in the calculation of the Stark effect. Expressions for the matrix elements are derived. Two simplified models for the study of the Stark effect in such molecules are also proposed and discussed. Copyright 1999 Academic Press.

Local Modes of Silane within Stretching Vibrational Polyads

Orientation of O(3) and SU(2)⊗CI representations in cubic point groups (Oh,Td) for application to molecular spectroscopy

Abstract We propose a detailed method for the symmetrization of the standard O (3) or SU (2)⊗ C I basis | j τ , m 〉 ( τ = g or u ) into the O h or T d point group. This is realized by means of an orientation matrix called G . The oriented basis obtained in this way allows matrix element calculations for rovibronic spectroscopic problems concerning octahedral or tetrahedral molecules. Particular attention has been put on careful phase choices. A numerical calculation of all the G matrix elements for both integer and half-integer j values up to 399/2 has been performed. Such high angular momentum values are necessary for the case of heavy molecules with high rotational excitation. To calculat…

On-Line Measurement of Gaseous Iodine Species During a PWR Severe Accident

International audience; Iodine is a highly radio-toxic element, due to its affinity to the thyroid, and represents the major part of the radioactivity released during a nuclear accident. In the context of nuclear safety and radio-protection, we are interested in identifying the iodine gaseous species which are released, in the nuclear power plants, under molecular (I$_2$) and organic (CH$_3$I) forms. Therefore, we are working on providing a spectroscopic database for both species. While the infrared spectrum of the ν6 band of methyl iodide was previously studied, only 4000 lines were assigned. We present the rovibrational analysis of a high quality experimental spectrum, of this band, recor…

Line positions and intensities in the band of ethylene near : An experimental and theoretical study

Abstract Recently, we built a tensorial formalism adapted to the spectroscopy of X2Y4 molecules. It is based on formalisms developed in Dijon for spherical-top molecules. This approach has the advantages to allow a systematic development of rovibrational interactions and to make global analyses easier to perform. We used this tool to carry out an analysis of the ν 12 band of 12C2H4 near 1450 cm - 1 , both in frequencies and intensities. 1240 line positions and 871 intensities, measured in a set of spectra recorded in Brussels, with global root mean square deviations of 1.6 × 10 - 4 cm - 1 and 1.88 % , respectively.

High-resolution stimulated Raman spectroscopy and analysis of the nu2, nu5 and 2 nu6 bands of 34SF6

9 p.Special Issue: Nineteenth Colloquium on High Resolution Molecular Spectroscopy, Salamanca 11–16 September 2005

The High Resolution Far-Infrared Spectrum of Methane at the SOLEIL Synchrotron

Fonction de partition du methane à haute température

Near-infrared radiative transfer modelling with different CH4 spectroscopic databases to retrieve atmospheric methane total amount

International audience; Atmospheric methane content can be retrieved from measurements of solar radiation attenuated by the atmosphere in the near infrared spectral region where the space-borne and ground-based spectrometers carry out regular measurements. It is shown, in the present work, that the different spectroscopic databases can give significantly different results for both forward simulations of the atmospheric transmittance and the inverse problem solution to retrieve the CH4 total content in the atmosphere using spectra measured by ground-based FTIR spectrometer in the near infrared spectral region. These discrepancies and the problem of the reduction of their influence on the atm…

Une interview du CO2

Measurements and Analysis of High Resolution Absorption Spectra of Ethylene within 5550 – 6300 cm-1

Absorption spectrum of the f(A1g) ← X(Eg), a(F2g) electronic transition of OsF6

Abstract The absorption spectrum of the visible band of OsF 6 has been recorded using a commercial spectrophotometer. The first vibronic assignments for this band have been realized using the analogy with the d ← X transition of IrF 6 . Some vibronic parameter values are derived.

Simulation de l'Effet Stark dans la Bande ν12 de l'Ethylène

Absorption spectrum of the and electronic transitions of ReF6

Abstract The absorption spectra of the near-infrared and ultraviolet bands of ReF6 have been recorded with a commercial spectrophotometer. The vibronic assignments previously published by different authors are critically revised. A non-perturbative method has been used to calculate the linear Jahn–Teller levels for the ν5 mode in the ground electronic state. Some new vibronic parameter values are derived. The ν5 linear Jahn–Teller parameter in the X G′ g electronic state is found to be D5=0.103(9). The ultraviolet absorption spectrum has enabled us to determine relatively accurate values of the crystal-field (10Dq) and spin-orbit (ζd) parameters.

Comparison of line-by-line and band models of near-IR methane absorption applied to outer planet atmospheres

Import OPTIWOS; International audience; Recent improvements in high spectral resolution measurements of methane absorption at wavenumbers between 4800 cm(-1) and 7919 cm(-1) have greatly increased the number of lines with known lower state energies, the number of weak lines, and the number of lines observed at low temperatures (Campargue, A., Wang, L, Kassi, S., Masat, M., Votava, O. [2010]. J. Quant. Spectrosc. Radiat. Trans. 111, 1141-1151; Campargue, A., Wang, L, Liu, A.W., Hu, S.M., Kassi, S. [2010]. Chem. Phys. 373, 203-210; Mondelain, D., Kassi, S., Wang, L.C. [2011]. Phys. Chem. Chem. Phys. 13, 7985-7996; Nikitin, A.V. et al. [2011a]. J. Mol. Spectrosc. 268, 93-106; Nikitin, A.V. et …

Ab InitioCalculations and High-Resolution Spectroscopy of the Bending Pentad of SiH2D2in the 10–16 μm Region

Abstract The SiH 2 D 2 asymmetric top has nine vibrational modes, five of them forming a pentad strongly perturbed by Coriolis interactions. High-level ab initio calculations of SiH 2 D 2 have been performed which yield numerous spectroscopic parameters related to the harmonic and anharmonic force fields. The bending pentad comprising ν 4 (A 1 ), ν 7 (B 1 ), ν 5 (A 2 ), ν 9 (B 2 ), and ν 3 (A 1 ) has been studied by high-resolution Fourier transform spectroscopy; the region 600–1050 cm −1 has been investigated with a resolution of ca. 4 × 10 −3 cm −1 . Raman BOXCARS spectroscopy has been used for the infrared inactive ν 5 band. The Raman apparatus function was 0.0054 cm −1 . Assignments of …

A methane data base for VAMDC

International audience

The high overtone and combination levels of SF6 revisited at Doppler-limited resolution: A global effective rovibrational model for highly excited vibrational states

Abstract Sulfur hexafluoride is an important prototypal molecule for modeling highly excited vibrational energy flow and multi quanta absorption processes in hexafluoride molecules of technological importance. It is also a strong greenhouse gas of anthropogenic origin. This heavy species, however, features many hot bands at room temperature (at which only 30% of the molecules lie in the ground vibrational state), especially those originating from the lowest, v 6 =1 vibrational state. Using a cryogenic long path cell with variable optical path length and temperatures regulated between 120 and 163 K, coupled to Synchrotron Radiation and a high resolution interferometer, Doppler-limited spectr…

Spectroscopy of XY2Z2 (C2v) Molecules: A Tensorial Formalism Adapted to the O(3)⊃Td⊃C2v Chain. Application to the Ground State of SO2F2

Abstract A tensorial formalism adapted to the case of quasi-spherical XY 2 Z 2 asymmetric tops such as SO 2 F 2 has been developed as an extension of the usual one for the tetrahedral molecules. We use the O (3)⊃ T d ⊃ C 2 v group chain. All the coupling coefficients and formulas for the computation of matrix elements are given for this chain. Such relations are then deduced in the C 2 v group itself. We also present a development of the Hamiltonian, dipole moment, and polarizability operators for the molecules under consideration using this formalism. These operators are involved in the calculation of the energies and intensities of rovibrational transitions and are essential for spectrum …

Can we ascertain that an archeological site contains intentional stellar alignments?

We study the different parameters that support the presence of intentional stellar alignments on an archaeological site. We develop a rigorous criterion to quantify the probability of fortuitous orientation on a starrise or a starset. We show that the magnitude of the considered stars and the precision of the angular measurements are the two preponderant parameters. Our study aims at establishing the basis of reliable methods for archaeoastronomy.

High-resolution spectroscopy and analysis of the nu3/2nu4 dyad of CF4

International audience; CF4 is a strong greenhouse gas of both anthropogenic and natural origin [D.R. Worton et al., Environ. Sci. Technol. 41, 2184 (2007)]. However, high-resolution infrared spectroscopy of this molecule has received only a limited interest up to now. Until very recently, the public databases only contained cross-sections for this species, but no detailed line list. We reinvestigate here the strongly absorbing ν3 region around 7.8 μm. New Fourier transform infrared (FTIR) spectra up to a maximal resolution of 0.0025 cm−1 have been recorded: (i) room-temperature spectra in a static cell and (ii) a supersonic expansion jet spectrum at a 23 K estimated temperature. Following …

Spherical Top Theory and Molecular Spectra

In this article, we present an overview of the present state of the art of the theory of high-resolution spherical-top spectra in the framework of the effective Hamiltonian approach. We describe the specific features of this class of molecules to explain the basic concepts of the theoretical methods used for the analysis (line positions and intensities) and the simulation of absorption (including pure rotation) and Raman spectra of such species. The non conventional formalism that we use is essentially based on irreducible tensor methods and is especially adapted to computational treatments and global analyses of complex interacting band systems. We give examples concerning mainly methane (…

Analyse en Fréquence et en Intensité des Bandes de l'Ethylène à 10 Microns

top data system (TDS) software for spectrum simulation of asymmetric molecules

Abstract The D 2 h TDS ( D 2 h Top Data System) program suite has been developed with the aim of studying any rovibrational band or polyad of X 2 Y 4 ( D 2 h ) asymmetric top molecules. It is based on the same principles as similar programs from our group already released for various molecular symmetries ( T d , O h , C 4 v , C 2 v ). We work in the O ( 3 ) ⊃ D 2 h chain and this choice has consequences on the method used to specify the input parameters of the programs for Hamiltonian and transition moment calculations. Two examples concerning the ν 12 and ν 2 bands of the C 2 H 4 molecule are presented. This suite consists of a series of FORTRAN programs called by a script. The whole packa…

The high-resolution far-infrared spectrum of methane at the SOLEIL synchrotron

International audience; As a tetrahedral molecule, methane has no permanent dipole moment. Its spectrum, however, displays faint absorption lines in the THz region, due to centrifugal distorsion effects. This is important for planetary applications since this region is used to measure methane concentration in some planetary atmospheres, in particular on Titan. Up to now, all measurements relied either on some old low resolution infrared absorption spectra, or on high resolution Stark measurements for low J values only. Even if these results have been reexamined recently [E. H. Wishnow, G. S. Orton, I. Ozier and H. P. Gush, J. Quant. Spectrosc. Radiat. Transfer 103, 102-117 (2007)], it seeme…

High-Resolution Spectroscopy and Analysis of the ν3 and ν4 Fundamentals of Monoisotopic 70GeF4

The first high-resolution study on germanium tetrafluoride is reported. We used a monoisotopic sample of (70)GeF(4). The FTIR spectra of the two infrared active fundamentals, namely the nu(4) (bending) and nu(3) (stretching) modes, were recorded at a temperature of ca. 210 K and a resolution (1/maximum optical path difference) of 0.0031 and 0.0023 cm(-1), respectively. These spectra were analyzed using the STDS software developed in Dijon. In both cases, we obtained a fit with a root mean square better than 1x10(-3) cm(-1). Both bands show very regular structures with no detectable perturbation. Copyright 2001 Academic Press.

VAMDC: Databases of Calculated Spectral Lines of Ethylene and Methane

Application of new methane linelists to Cassini and Earth-based data of Titan

International audience

Breakdown of the Reduction of the Rovibrational Hamiltonian: The Case of S18O2F2

Abstract The ground state rotational spectrum of the near-spherical top molecule S18O2F2 (sulfuryl fluoride) has been measured from 50 to 700 GHz. As for the parent isotopologue, S16O2F2 [K. Sarka, J. Demaison, L. Margules, I. Merke, N. Heineking, H. Burger, H. Ruland, J. Mol. Spectrosc. 200 (2000) 55–64], it was necessary to use a non-reduced Hamiltonian in order to obtain a satisfactory fit. It was possible to determine six quartic centrifugal distortion constants (instead of five for a standard asymmetric top) and five sextic constants (one of them not existing in the reduced Hamiltonian) could also be determined. This ground state level has also been analysed thanks to a tensorial forma…

Near-Infrared Radiative Transfer Modeling with Different CH4 Databases to Retrieve Atmospheric Methane Total Amount

High-resolution Fourier transform infrared spectroscopy and analysis of the ν3 fundamental band of P4

Abstract We present the first high-resolution infrared absorption study of the ν 3 fundamental of white phosphorus, P 4 . This spectrum has been analyzed using the STDS (Spherical Top Data System) software. The band center lies at 466.286 cm −1 . With the approximation ( Bζ ) 3 =− B 0 /2, we found that the ground-state bond length is r 0 =219.58 pm. This value is consistent with that of ab initio studies reported previously but significantly different from a value obtained from a Raman study.

Experimental IR study and ab initio modelling of ethylene adsorption in a MFI - type host zeolite.

International audience; Different ab initio methods and experimental results are used to investigate the effect of the adsorption of one ethylene molecule on silicalite-1, a MFI type zeolite. We used simplified models to simulate a portion of a straight or sinusoidal channel of silicalite-1 at a quantum level. The calculated absorption spectra of the models are qualitatively in good agreement with the experimental FTIR spectrum of silicalite-1. Additionally we simulate the FTIR spectrum of the isolated ethylene molecule and that of an ethylene molecule in interaction with the above-mentioned zeolite models. Results are discussed depending on the method and specific basis set and compared wi…

Experimental Study and Ab Initio Modelling of the Ethylene Adsorption in a MFI-Type Host Zeolite

Methane line parameters in the HITRAN2012 database

International audience; The compilation of methane molecular line parameters was updated to include new global analyses and measurements for 12CH4, 13CH4 and 12CH3D. Over 70% of the methane parameters in HITRAN2008 were replaced; existing parameters retained were the microwave lines and the Dyad of 13CH4 near 7 μm and ν6 of 13CH3D near 8.7 μm, 12CH3D (7-4076 cm-1), hot bands of 12CH4 (1887-3370 cm-1) and normal sample CH4 (4800-5550 cm-1 and 8000-9200 cm-1). With a minimum intensity at 296 K in units of cm-1/(molecule cm-2) set to 10-37 for the far-IR and 10-29 for the mid- and near-IR, the methane database increased from 290,091 lines in HITRAN2008 to 468,013 lines, and three-fourths of th…

High resolution spectroscopy and the first global analysis of the Tetradecad region of methane 12CH4.

We present the first detailed analysis of the infrared spectrum of methane (12)CH4 in the so-called Tetradecad region from 2.1 to 1.6 μm (4760-6250 cm(-1)). New experimental high resolution FTIR spectra at 78 K and at room temperature combined with improved theoretical modeling have allowed quantum assignments to be greatly extended in this region. A global fit of all assigned lines of (12)CH4 in the 0-6200 cm(-1) region has been performed. In the end, 3012 line positions and 1387 intensities of 45 individual subbands of the Tetradecad were modeled up to J = 14. The root mean square deviations were 0.023 cm(-1) for line positions and 13.86% for line intensities in the Tetradecad region itse…

High-Resolution Spectroscopy and Global Analysis of the Tetradecad Region of Methane 12CH4

Global analysis of the high resolution infrared spectrum of methane 12CH4 in the region from 0 to 4800 cm-1

International audience; We report the global analysis of methane (12CH4) lines from high resolution rovibrational spectra including accurate line positions and intensities in the region 0–4800 cm−1. This covers four polyads: The Ground State Monad (rotational levels), the Dyad (940–1850 cm−1, 2 vibrational levels, 2 sublevels), the Pentad (2150–3350 cm−1, 5 vibrational levels, 9 sublevels) and the Octad (3550–4800 cm−1, 8 vibrational levels, 24 sublevels) and some of the associated hot bands (Pentad−Dyad and Octad−Dyad). New Fourier transform infrared (FTIR) spectra of the Pentad and Octad regions have been recorded with a very high resolution (better than 0.001 cm−1 instrumental bandwidth,…

Jet-cooled FTIR spectroscopy and analysis of the C–O stretch fundamental of Ni(CO)4

Rovibrational spectra of the C–O stretch band (ν5) of Ni(CO)4 have been recorded at 0.006 cm− 1 resolution by coupling a low pressure continuous supersonic jet with a high resolution interferometer. The spectrum has been analysed thanks to the STDS software (see http://icb.u-bourgogne.fr/OMR/SMA/SHTDS/) that implements the tensorial formalism developed in the Dijon group for tetrahedral molecules. We obtain a very satisfying simulation thanks to an effective Hamiltonian expanded up to order 3. The asymmetry of the high-J lines is due to a small tetrahedral splitting and is well reproduced. The root mean square deviation is 0.96 × 10− 3 cm− 1. The Coriolis constant is somewhat larger than fo…

Resolving the forbidden band of SF6

Sulfur hexafluoride is an important molecule for modeling thermophysical and polarizability properties. It is also a potent greenhouse gas of anthropogenic origin, whose concentration in the atmosphere, although very low is increasing rapidly; its global warming power is mostly conferred by its strong infrared absorption in the ν3 S-F stretching region near 948 cm(-1). This heavy species, however, features many hot bands at room temperature (at which only 31% of the molecules lie in the ground vibrational state), especially those originating from the lowest, v6 = 1 vibrational state. Unfortunately, the ν6 band itself (near 347 cm(-1)), in the first approximation, is both infrared- and Raman…

Rotational Raman spectroscopy of ethylene using a femtosecond time-resolved pump-probe technique.

154309; Femtosecond Raman-induced polarization spectroscopy (RIPS) was conducted at low pressure (250 mb at 295 K and 400 mb at 373 K) in ethylene. The temporal signal, resulting from the beating between pure rotational coherences, was measured with a heterodyne detection. The temporal traces were converted to the frequency domain using a Fourier transformation and then analyzed thanks to the D2hTDS software (http://www.u-bourgogne.fr/LPUB/shTDS.html) dedicated to X2Y4 molecules with D2h symmetry. The effective Hamiltonian was expanded up to order 2, allowing the determination of five parameters with an rms of 0.017 cm(-1). Special care was taken in the precise modeling of intensities, taki…

Theoretical Investigation of the Etylene Dimer: Interaction Energy and Dipole Moment

High‐resolution stimulated Raman spectroscopy and analysis of line positions and assignments for the ν 2 and ν 3 bands of 13 C 2 H 4

High-resolution stimulated Raman spectra of13C2H4 in the regions of the ν2 and ν3 Raman active modes have been recorded at two temperatures (145 and 296 K) based on the quasi continuous-wave (cw) stimulated Raman spectrometer at Instituto de Estructura de la Materia IEM-CSIC in Madrid. A tensorial formalism adapted to X2Y4 planar asymmetric tops with D2h symmetry (developed in Dijon) and a program suite called D2hTDS (now part of the XTDS/SPVIEW spectroscopic software) were proposed to analyze and calculate the high-resolution spectra. A total of 103 and 51 lines corresponding to ν2 and ν3 Raman active modes have been assigned and fitted in wavenumber with a global root mean square deviatio…

High-resolution spectroscopy and analysis of the ν4 band of 80SeF6

Abstract The Fourier-transform spectrum of the ν4 bending region of 80 SeF 6 around 435 cm −1 has been recorded at a temperature of 217 K with a resolution of 2.3×10 −3 cm −1 . This fundamental has been analyzed using the set of programs called highly spherical top data system (HTDS). Altogether 958 transitions were assigned and fitted with an rms of 0.0003 cm −1 . The effective Hamiltonian was developed up to the fourth order. Parameters and simulations are presented. The ν4 band center is located at 435.099 cm −1 .

Applications of a new set of methane line parameters to the modeling of Titan's spectrum in the 1.58 μm window

International audience; In this paper we apply a recently released set of methane line parameters (Wang et al., 2011) to the modeling of Titan spectra in the 1.58 mu m window at both low and high spectral resolution. We first compare the methane absorption based on this new set of methane data to that calculated from the methane absorption coefficients derived in situ from DISR/Huygens (Tomasko et al., 2008a; Karkoschka and Tomasko, 2010) and from the band models of Irwin et al. (2006) and Karkoschka and Tomasko (2010). The Irwin et al. (2006) band model clearly underestimates the absorption in the window at temperature-pressure conditions representative of Titan's troposphere, while the Ka…

High-Resolution Infrared and Raman Spectroscopy of SF6 : The State-of-the-Art in June 2006

Introduction to the special issue on molecular spectroscopy, atmospheric composition and climate change

International audience

High-Resolution Stimulated Raman Spectroscopy and Analysis of the ν5 (C-H) Stretching Mode of C2H4

New assignments in the 2μm transparency window of the 12CH4 Octad band system

Abstract This paper reports new assignments of rovibrational transitions of 12 CH 4 bands in the range 4600–4887  cm −1 which is usually referred to as a part of the 2 μm methane transparency window. Several experimental data sources for methane line positions and intensities were combined for this analysis. Three long path Fourier transform spectra newly recorded in Reims with 1603 m absorption path length and pressures of 1, 7 and 34 hPa for samples of natural abundance CH 4 provided new measurements of 12 CH 4 lines. Older spectra for 13 CH 4 (90% purity) from JPL with 73 m absorption path length were used to identify the corresponding lines. Most of the lines in this region belong to th…