Analysis of self-broadened pure rotational and rovibrational lines of methyl chloride at room temperature

International audienceRovibrational absorption spectra of methyl chloride in the spectral region between 2800 and 3200 cm 1 were recorded with a high-resolution Fourier spectrometer. A multispectrum fitting procedure was used to analyze 527 transitions of the ν1 band and to retrieve the self-broadening coefficients for various J- and K-values with an estimated accuracy around 8%. Pure rotational transitions of CH3Cl in the submillimeter/terahertz region (0.2-1.4 THz) were also investigated using two complementary techniques of frequency-multiplication and continuous-wave photomixing. 43 pure rotational self-broadening coefficients were extracted with the accuracy between 3 and 5%. The whole set of measured values was used to model the J- and K-rotational dependences of the self-broadening coefficients by second-order polynomials. In addition, semi-classical calculations were performed, based on the real symmetric-top geometry of the active molecule, an intermolecular potential model including not only the dominant electrostatic but also the short-range forces, as well as on an exact classical treatment of the relative translational motion of the colliding partners. Comparison of all experimental and theoretical results shows similar rotational dependences and no significant vibrational dependence, so that extrapolations to other spectral regions should be straightforward

Absorption line shape recovery beyond the detection bandwidth limit: application to the precision spectroscopic measurement of the Boltzmann constant

22 pagesInternational audienceA theoretical model of the influence of detection bandwidth properties on observed line shapes in laser absorption spectroscopy is described. The model predicts artificial frequency shifts, extra broadenings and line asymmetries which must be taken into account in order to obtain accurate central frequencies and other spectroscopic parameters. This reveals sources of systematic effects most probably underestimated so far potentially affecting spectroscopic measurements. This may impact many fields of research, from atmospheric and interstellar physics to precision spectroscopic measurements devoted to metrological applications, tests of quantum electrodynamics or other fundamental laws of nature. Our theoretical model is validated by linear absorption experiments performed on H2O and NH3 molecular lines recorded by precision laser spectroscopy in two distinct spectral regions, near- and mid-infrared. Possible means of recovering original line shape parameters or experimental conditions under which the detection bandwidth has a negligible impact, given a targeted accuracy, are proposed. Particular emphasis is put on the detection bandwidth adjustments required to use such high-quality molecular spectra for a spectroscopic determination of the Boltzmann constant at the 1 ppm level of accuracy

Guide de la fabrication économique des engrais au moyen de tous les éléments qui peuvent être avantageusement employés en agriculture... : précédé d'un aperçu statistique sur la production générale des subsistances / par F. Rohart,...

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État de la question phylloxera : moyens de prolonger les vignes atteintes... conséquences agricoles et commerciales de la destruction du phylloxera / par F. Rohart,...

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Question générale de l'enseignement, à propos de l'enseignement supérieur de l'agriculture à l'École centrale / par F. Rohart,...

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La doctrine des engrais chimiques au point de vue des intérêts agricoles : réponse aux conférences de Vincennes, examen des résultats obtenus / par F. Rohart,...

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Pieux souvenir d'une famille éplorée : Maximes et pensées de Alfred Rohart, décédé le 20 mars 1866, dans sa 22e année. Détails sur ses derniers moments... [Signé : F. Rohart]

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Traité théorique et pratique de la fabrication de la bière / par F. Rohart...

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Techniques de négociation et utilisation des modes alternatifs de résolution des différends en procédure amiable et collective

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Xenon-broadened CO line shapes in the fundamental band at 349 K

SCOPUS: ar.jinfo:eu-repo/semantics/publishe