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…

Global frequency and intensity analysis of the / / / band system of 12 C 2 H 4 at 10 μm using the D 2h Top Data System

Abstract A global frequency and intensity analysis of the infrared tetrad of 12C2H4 located in the 600 – 1500 cm − 1 region was carried out using the tensorial formalism developed in Dijon for X2Y4 asymmetric-top molecules. It relied on spectroscopic information available in the literature and retrieved from high-resolution Fourier transform infrared spectra recorded in Brussels in the frame of either the present or previous work. In particular, 645 and 131 line intensities have been respectively measured for the weak ν10 and ν4 bands. Including the Coriolis interactions affecting the upper vibrational levels 101, 71, 41 and 121, a total of 10 757 line positions and 1645 line intensities ha…

The HITRAN2016 molecular spectroscopic database

This paper describes the contents of the 2016 edition of the HITRAN molecular spectroscopic compilation. The new edition replaces the previous HITRAN edition of 2012 and its updates during the intervening years. The HITRAN molecular absorption compilation is composed of five major components: the traditional line-by-line spectroscopic parameters required for high-resolution radiative-transfer codes, infrared absorption cross-sections for molecules not yet amenable to representation in a line-by-line form, collision-induced absorption data, aerosol indices of refraction, and general tables such as partition sums that apply globally to the data. The new HITRAN is greatly extended in terms of …

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

High-Resolution Photoacoustic Raman-Spectroscopy of Gases

0377-0486; A high-resolution photoacoustic Raman spectroscopy experiment is described. The resolution achieved by using two single-mode pulsed lasers is about 0.0054 cm-1 (full width at half maximum intensity). The experiment was tested first on the v1/2v2 bands of CO2 and gave an increase of at least about one order of magnitude in the signal-to-noise ratio with respect to stimulated Raman spectroscopy at low pressure (ca. 10 Torr almost-equal-to 13 kPa). The sensitivity is also demonstrated by the study of the weak hot band v1 + v2 - v2 of CO2. In both cases, the experimental line shape is well reproduced by taking into account Doppler and collisional effects. A comparison with CARS spect…

FRIPON: a worldwide network to track incoming meteoroids

Context. Until recently, camera networks designed for monitoring fireballs worldwide were not fully automated, implying that in case of a meteorite fall, the recovery campaign was rarely immediate. This was an important limiting factor as the most fragile - hence precious - meteorites must be recovered rapidly to avoid their alteration. Aims. The Fireball Recovery and InterPlanetary Observation Network (FRIPON) scientific project was designed to overcome this limitation. This network comprises a fully automated camera and radio network deployed over a significant fraction of western Europe and a small fraction of Canada. As of today, it consists of 150 cameras and 25 European radio receiver…

Nonlinear Raman Spectroscopy in Gases

0022-2860; Recent progress in high-resolution non-linear coherent Raman spectroscopy in the gas phase is reviewed. An instrumental spectral resolution of less than 100 MHz can be routinely achieved. It is limited by the convoluted linewidths of the lasers used for excitation and is of particular advantage in the gas phase, where the rotational structure of vibrational bands is to be resolved. It also allows the measurement of linewidths and line positions with an accuracy of 60 MHz when an appropriate wavemeter is used for calibration. After a short overview of the various techniques being used, examples of recent results of the evaluation of measurements on nitrogen, oxygen, carbon dioxide…

High-resolution photoacoustic Raman spectroscopy of gases

A high-resolution photoacoustic Raman spectroscopy experiment is described. The resolution achieved by using two single-mode pulsed lasers is about 0.0054 cm −1 (full width at half maximum intensity). The experiment was tested first on the v 1 /2v 2 bands of CO 2 and gave an increase of at least about one order of magnitude in the signal-to-noise ratio with respect to stimulated Raman spectroscopy at low pressure (ca. 10 Torr ≃ 1.3 kPa). The sensitivity is also demonstrated by the study of the weak hot band v 1 +v 2 −v 2 of CO 2 . In both cases, the experimental line shape is well reproduced by taking into account Doppler and collisional effects. A comparison with CARS spectra was also made

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