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…

2nu3 band of 12CF4 and its simultaneous analysis with nu3

Abstract A nearly Doppler-limited spectrum of the 2ν 3 band of the 12 CF 4 molecule between 2536.0 and 2599.8 cm −1 was recorded at T = 77 K using difference-frequency laser spectroscopy. The simultaneous analysis of the ground (G.S.), ν 3 = 1, and ν 3 = 2 states was performed using an isolated band model to sixth order in the tetrahedral formalism. Fourteen hundred seventy-five transitions were assigned through J = 35 to the F 2 and E vibrational components of the ν 3 = 2 level. A total of 1864 transition frequencies were fit simultaneously (1000 2ν 3 - G.S. newly assigned transitions together with 575 ν 3 - G.S. and 289 ν 3 - ν 3 transitions already reported in the literature). The ground…

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

New measurements and global analysis of chloromethane in the region from 0 to 1800cm−1

Abstract New high resolution Fourier transform spectra of pure 12CH335Cl and 12CH337Cl isotopomers of chloromethane have been recorded in Wuppertal covering the region from 600 to 3800 cm−1. New rotational transitions within the v2=1, v5=1, and v3=2 states have been measured at Lille. A first global analysis of the lower four band systems of the molecule (700–1800 cm−1) is reported. The model was based on an effective Hamiltonian and dipole moment expressed in terms of irreducible tensor operators. A common set of 125 effective hamiltonian parameters (sixth order) has been adjusted to fit simultaneously some 11 000 IR data for each of the isotopomers including 153 mm wave data for 12 CH3 35…

Global analysis of 12CH335Cl and 12CH337Cl: simultaneous fit of the lower five polyads (0–2600cm−1)

Abstract The global analysis of the infrared spectrum of chloromethane involving the ground state and the 13 vibrational states lying up to 2600 cm −1 is reported. This work incorporates and extends to the fifth polyad, the preliminary study of the lower four polyads published by [J. Mol. Spectrosc. 221 (2003) 199]. More than 20 000 transitions (including numerous hot bands) for each isotopomer 12 CH 3 35 Cl and 12 CH 3 37 Cl have been assigned and fitted with a standard deviation of about 3 × 10 −4  cm −1 close to the experimental precision. A common set of 288 (resp. 303) effective parameters was determined for each isotopomer. Our global model allowed us to reproduce simultaneously and a…

Improved Algorithms for the Modeling of Vibrational Polyads of Polyatomic Molecules: Application toT,O, andC3Molecules

Abstract Improved algorithms for the construction of rovibrational operators of polyatomic molecules are presented. Vibrationally diagonal and off-diagonal terms are obtained by a specific coupling scheme of creation and annihilation elementary operators. Recursive procedures are used to generate all possible terms and associated basis functions as well as to calculate matrix elements and commutators. Explicit formulations are given forTd,Oh, andC3vmolecules.

The MIRS computer package for modeling the rovibrational spectra of polyatomic molecules

International audience; The MIRS spectroscopic software for the modeling of ro-vibrational spectra of polyatomic molecules is presented. It is designed for the global treatment of complex band systems of molecules to take full account of symmetry properties. It includes e cient algorithms based on the irreducible tensor formalism. Predictions and simultaneous data fi tting (positions and intensities) are implemented as well as advanced options related to group theory algebra. Illustrative examples on CH3D, CH4, CH3Cl and PH3 are reported and the present status of data available is given. It is written in C++ for standard PC computer operating under Windows. The full package including on-lin…

Line intensities of CH3D in the Triad region: 6–10μm

Abstract Line intensities of the three lowest fundamentals of the 12CH3D Triad are modeled with an RMS of 3.2% using over 2100 observed values retrieved by multispectrum fitting of enriched sample spectra recorded with two Fourier transform spectrometers. The band strengths of the Triad in units of 10−18 cm−1/(molecule cm−2) at 296 K are, respectively, 2.33 for ν6 (E) at 1161 cm−1, 1.75 for ν3 (A1) at 1307 cm−1 and 0.571 for ν5 (E) at 1472 cm−1. The total calculated absorption arising from 12CH3D Triad fundamentals is 4.65×10−18 cm−1/(molecule cm−2) at 296 K. In addition, some 740 intensities of nine hotbands are fitted to 8.1%; most of the hotband measurements belong to 2ν6−ν6 and ν3+ν6−ν3…

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 …

Extension of the MIRS computer package for the modeling of molecular spectra : from effective to full ab initio ro-vibrational hamiltonians in irreducible tensor form

The MIRS software for the modeling of ro-vibrational spectra of polyatomic molecules was considerably extended and improved. The original version (Nikitin, et al. JQSRT, 2003, pp. 239--249) was especially designed for separate or simultaneous treatments of complex band systems of polyatomic molecules. It was set up in the frame of effective polyad models by using algorithms based on advanced group theory algebra to take full account of symmetry properties. It has been successfully used for predictions and data fitting (positions and intensities) of numerous spectra of symmetric and spherical top molecules within the vibration extrapolation scheme. The new version offers more advanced possib…

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

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

The infrared spectrum of CH 3 D between 900 and 3200 cm −1 : extended assignment and modeling

Abstract The high resolution infrared spectrum of CH 3 D in the region from 900 to 3200 cm −1 has been analyzed on the basis of Fourier transform spectra recorded at Kitt Peak and at Giessen. A theoretical model for an effective hamiltonian in terms of irreducible tensor operators recently adapted to symmetric top molecules has been used in order to consider simultaneously all available transitions between the lowest three polyads of the molecule: the Ground State (G.S.), the Triad (three interacting fundamental bands in the 8 μm region) and the Nonad (nine interacting bands in the 4 μm region). A preliminary simultaneous fit of 3467 Triad–G.S., 5208 Nonad–G.S., and 2487 Nonad–Triad (hot ba…

Analysis of the CH3D Nonad from 2000 to 3300 cm−1

As part of the simultaneous analysis of line positions and intensities of the first two polyads of monodeuterated methane, the results achieved for the 3 to 5 mu m region are reported.

The 1997 spectroscopic GEISA databank

International audience; The current version GEISA-97 of the computer-accessible database system GEISA (Gestion et Etude des Informations Spectroscopiques Atmosphériques: Management and Study of Atmospheric Spectroscopic Information) is described. This catalogue contains 1,346,266 entries. These are spectroscopic parameters required to describe adequately the individual spectral lines belonging to 42 molecules (96 isotopic species) and located between 0 and 22,656 cm-1. The featured molecules are of interest in studies of the terrestrial as well as the other planetary atmospheres, especially those of the Giant Planets. GEISA-97 contains also a catalog of absorption cross-sections of molecule…

Preliminary analysis of CH3D from 3250 to 3700 cm(-1)

International audience; The infrared spectrum of CH3D from 3250 to 3700 cm(-1) was studied for the first time to assign transitions involving the nu(2) + nu(3), nu(2) + nu(5), nu(2) + nu(6), nu(3) + 2(nu 6) and 3 nu(6) vibrational states. Line positions and intensities were measured at 0.011 cm(-1) resolution using Fourier transform spectra recorded at Kitt Peak with isotopically enriched samples. Some 2852 line positions (involving over 900 upper state levels) and 874 line intensities were reproduced with RMS values of 0.0009 cm(-1) and 4.6%, respectively. The strongest bands were found to be nu(2) + nu(3) at 3499.7 cm(-1) and nu(2) + nu(6) at 3342.5 cm(-1) with integrated strengths, respe…

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

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

Global modeling of the lower three polyads of PH_{3} Preliminary results

International audience; In order to model the high-resolution infrared spectrum of the phosphine molecule in the 3 mu m region, a global approach involving the lower three polyads of the molecule (Dyad, Pentad and Octad) as been applied using an effective hamiltonian in the form of irreducible tensors. This model allowed to describe all the 15 vibrational states involved and to consider explicitly all relevant ro-vibrational interactions that cannot be accounted for by conventional perturbation approaches. 2245 levels (up to J=14) observed through transitions arising from 34 cold and hot bands including all available existing data as well as new experimental data have been fitted simultaneo…

Current status of the global modeling of the lower three polyads of PH3 (position and intensities)

As part of extensive efforts to support remote sensing of Jupiter and Saturn many works have been devoted to the high-resolution infrared spectrum of phosphine. However, at present, the line parameters of phosphine (positions and intensities) in the 3 \mu m region rely essentially on the empirical database reported in 2006. So far, only weakly interacting features could be fitted using isolated band models while strongly interacting states were left out. The goal of the present work is to achieve a comprehensive modeling of the lower three polyads of the molecule. The simultaneous analysis of the dyad, pentad and octad of PH_3 has been undertaken using an effective hamiltonian in the form o…

Methane line parameters in HITRAN

Abstract Two editions of the methane line parameters (line positions, intensities and broadening coefficients) available from HITRAN in 2000 and 2001 are described. In both versions, the spectral interval covered was the same (from 0.01 to 6184.5 cm −1 ), but the database increased from 48,033 transitions in 2000 to 211,465 lines in 2001 because weaker transitions of 12 CH 4 and new bands of 13 CH 4 and CH3D were included. The newer list became available in 2001 in the “Update” section of HITRAN. The sources of information are described, and the prospects for future improvements are discussed.

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 …

New ground state constants of 12CH335Cl and 12CH337Cl from global polyad analysis

Abstract A global analysis of the infrared spectrum of chloromethane involving the ground state and the 13 vibrational states lying up to 2600 cm −1 was recently achieved using high resolution Fourier transform spectra of pure isotopomers. More than 20 000 transitions (cold and hot bands) for each isotopomer 12 CH 3 35 Cl and 12 CH 3 37 Cl have been assigned and fitted with a standard deviation of about 3 × 10 −4  cm −1 close to the experimental precison. As part of this global effort, improved ground state constants up to sextic centrifugal distortion terms have been determined for each isotopomer taking advantage of the numerous allowed and perturtation-allowed transitions simultaneously …

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

International audience

The High Resolution Infrared Spectrum of CH3D in the Region 900–1700 cm−1

The high resolution absorption spectrum of CH(sub 3)D in the region of 900-1700 cm(sup -1) has been revisited on the basis of new long path experimental data recorded with the Fourier transform spectrometer at Kitt Peak. A theoretical model used previously for spherical rotors has been adapted for polyatomic molecules in order to analyze the vibrational polyads of CH(sub 3)D simultaneously.

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,…

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…