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70 th International Symposium on Molecular Spectroscopy / Champaign-Urbana, Illinois, USA, June 22–26, 2015 LOW-TEMPERATURE COLLISIONAL BROADENING IN THE.

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Presentation on theme: "70 th International Symposium on Molecular Spectroscopy / Champaign-Urbana, Illinois, USA, June 22–26, 2015 LOW-TEMPERATURE COLLISIONAL BROADENING IN THE."— Presentation transcript:

1 70 th International Symposium on Molecular Spectroscopy / Champaign-Urbana, Illinois, USA, June 22–26, 2015 LOW-TEMPERATURE COLLISIONAL BROADENING IN THE FAR-INFRARED CENTRIFUGAL DISTORSION SPECTRUM OF CH 4 Vincent BOUDON 1, Jean VANDER AUWERA 2, Laurent MANCERON 3,4, Fridolin KWABIA TCHANA 5, Tony GABARD 1, Badr AMYAY 1, Mbaye FAYE 3 1 Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 6303, Univ. Bourgogne Franche-Comté / CNRS 2 Service de Chimie Quantique et Photophysique, Université Libre de Bruxelles 3 AILES Beamline, SOLEIL Synchrotron 4 Laboratoire MONARIS, UMR 8233, Université Pierre et Marie Curie / CNRS 5 LISA, UMR 7583, Université Paris-Est Créteil et Université Paris-Diderot / CNRS

2 70 th International Symposium on Molecular Spectroscopy / Champaign-Urbana, Illinois, USA, June 22–26, 2015 Context and method of this study Methane (CH 4 ) in Titan’s stratosphere measured in the far-infrared First high-resolution spectrum at SOLEIL V. Boudon et al., JQSRT 111, 1117 (2010) Self- and nitrogen- broadening measured at room temperature M. Sanzharov et al., JQSRT 113, 1874 (2012) Image Credit: NASA/JPL/Space Science Institute – PIA06230

3 70 th International Symposium on Molecular Spectroscopy / Champaign-Urbana, Illinois, USA, June 22–26, 2015 Example: Herschel / PACS observation of Titan Spectrum: Courtesy Dr. Miriam Rengel

4 70 th International Symposium on Molecular Spectroscopy / Champaign-Urbana, Illinois, USA, June 22–26, 2015 I. Experimental setup

5 70 th International Symposium on Molecular Spectroscopy / Champaign-Urbana, Illinois, USA, June 22–26, 2015 AILES beamline at SOLEIL High Resolution Absorption Spectroscopy in the Far-IR Synchrotron beam entrance Interferometer Multipass cell Bolometer detectors Maximum spectral resolution = 0.001 cm -1 Spectral range= 7-1000 cm -1

6 70 th International Symposium on Molecular Spectroscopy / Champaign-Urbana, Illinois, USA, June 22–26, 2015 Coolable long-path gas cell Adapted optics for long path (up to 150 m) Four compartment chamber Sample gas Convection-cooling gas (He) Liquid Nitrogen reservoir Insulating vacuum 1m Accurate far infrared high resolution spectra of diluted gas samples and mixture at temperatures : 400 – 90K F. Kwabia Tchana et al., Rev. Sci. Instrum. 84, 093101 (2013)

7 70 th International Symposium on Molecular Spectroscopy / Champaign-Urbana, Illinois, USA, June 22–26, 2015 II. Experimental results

8 70 th International Symposium on Molecular Spectroscopy / Champaign-Urbana, Illinois, USA, June 22–26, 2015 Pure CH 4 overview (transmission) R(9) R(8)R(7)R(6)R(5)R(4)R(10) R(11) R(12)

9 70 th International Symposium on Molecular Spectroscopy / Champaign-Urbana, Illinois, USA, June 22–26, 2015 Overview under different conditions (absorbance)

10 70 th International Symposium on Molecular Spectroscopy / Champaign-Urbana, Illinois, USA, June 22–26, 2015 R(6) and R(7) clusters

11 70 th International Symposium on Molecular Spectroscopy / Champaign-Urbana, Illinois, USA, June 22–26, 2015 R(8) and R(9) clusters

12 70 th International Symposium on Molecular Spectroscopy / Champaign-Urbana, Illinois, USA, June 22–26, 2015 R(9) cluster

13 70 th International Symposium on Molecular Spectroscopy / Champaign-Urbana, Illinois, USA, June 22–26, 2015 Preliminary simulations for pure CH 4

14 70 th International Symposium on Molecular Spectroscopy / Champaign-Urbana, Illinois, USA, June 22–26, 2015 III. Broadening coefficients

15 70 th International Symposium on Molecular Spectroscopy / Champaign-Urbana, Illinois, USA, June 22–26, 2015 Measured self-broadening coefficients Very preliminary! !

16 70 th International Symposium on Molecular Spectroscopy / Champaign-Urbana, Illinois, USA, June 22–26, 2015 Measured N 2 -broadening coefficients Very preliminary! !

17 70 th International Symposium on Molecular Spectroscopy / Champaign-Urbana, Illinois, USA, June 22–26, 2015 Calculation at 120 K Very preliminary! !

18 70 th International Symposium on Molecular Spectroscopy / Champaign-Urbana, Illinois, USA, June 22–26, 2015 Calculation at 160 K Very preliminary! !

19 70 th International Symposium on Molecular Spectroscopy / Champaign-Urbana, Illinois, USA, June 22–26, 2015 IV. Conclusion and perspectives

20 70 th International Symposium on Molecular Spectroscopy / Champaign-Urbana, Illinois, USA, June 22–26, 2015 Conclusions First line broadening measurements at low-temperature in the far infrared Pure CH 4 and various CH 4 /N 2 mixings Preliminary measurements of self- and nitrogen-broadening coefficients Preliminary semi-classical calculations of self- and nitrogen-broadening coefficients Perspectives for CH 4 Temperature dependence of broadening coefficients Semi-classical calculations Improved databases for planetary applications


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