Showing papers by "Vincent Boudon published in 2007"

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

Abstract: [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 information on the atmosphere and surface properties of these areas. The latter seem to indicate a strong decrease of Titan's surface albedo between 2.03 and 2.12 μm in all areas. This is compatible with the presence of ices such as CH4 and H2O at the surface. Sensitivity tests on the influence of the haze profile and the methane absorption on these results were performed.

High-resolution stimulated Raman spectroscopy and analysis of the ν1 stretching band of GeD4

Abstract: 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.

Local modes of silane within the framework of stretching vibrational polyads

Abstract: We define stretching relative equilibria (RE) of silane and other similar tetrahedral molecules in terms of the dynamical polyad symmetry which assumes the resonance condition 1:1 between the two stretching vibrational modes ν1 and ν3 of the molecule. Exploiting symmetry and topology arguments and reducing the dimension of the classical mechanical system, we find these RE. One of them, with local symmetry C3v and minimal energy within a polyad, corresponds to the local modes. We give the upper energy limit of the local mode localization within a polyad.

Spview and xtds: graphical tools for the analysis and simulation of high-resolution molecular spectra

Abstract: Author Institution: Institut Carnot de Bourgogne, UMR 5209 CNRS-Universite de Bourgogne, 9. Av. A. Savary, BP 47870, F-21078 Dijon Cedex, France

Jet-Cooled FTIR Spectroscopy and Analysis of the ν5 C–O Stretch Fundamental of Ni(CO)4

Abstract: 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 for other spherical-top carbonyls like Mo(CO)6 and W(CO)6 and, as a consequence, the level structure displays a standard three-branch structure, typical for triply degenerate fundamentals.