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High-Lying Rotational Levels of Water obtained by FIR Emission Spectroscopy L. H. Coudert, a M.-A. Martin, b O. Pirali, b D. Balcon, b and M. Vervloet.

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Presentation on theme: "High-Lying Rotational Levels of Water obtained by FIR Emission Spectroscopy L. H. Coudert, a M.-A. Martin, b O. Pirali, b D. Balcon, b and M. Vervloet."— Presentation transcript:

1 High-Lying Rotational Levels of Water obtained by FIR Emission Spectroscopy L. H. Coudert, a M.-A. Martin, b O. Pirali, b D. Balcon, b and M. Vervloet b a LISA, CNRS/Universities Paris Est and Paris Diderot, Créteil, France b Ligne AILES - Synchrotron SOLEIL, Gif-sur-Yvette, France

2 Why High-lying Rotational levels? Spectrum of water at high temperature Water at a temperature of  K has been detected around supergiant stars. 1 Hot water is expected to be found in extrasolar gas-giant planets like HD 209458b 2-3 characterized by a temperature of  K. 1 T. Tsuji, ApJ. 540 (2000) L99 2 http://www.nasa.gov/centers/godard/new/topstory/2007/cloudy_world.html 3 http://www.nasa.gov/vision/universe/newworlds/Osiris_leaks.html

3 Overview The new experimental data The line position analysis The data set Results Comparison with other data bases Line strength comparison

4 Experimental setup Bruker IFS 125 Radio Frequency discharge Fourier transform interferometer of the Ailes beam line at Soleil

5 Radio frequency discharge F = 13.6 MHz Power = 1000 W Pressures = 10 and 15 Torr Temperature  1000 K Faraday cage Pyrex cell Fan

6               Low pressure spectrum 

7           High pressure spectrum 

8 The assigned lines Up to the 2nd triad, number of assigned lines is  There are also lines for the first hexad

9 The theoretical approach 1. J. Mol. Spec. 154 (1992) 427. 2. J. Mol. Spec. 165 (1994) 406. 3. J. Mol. Spec. 181 (1997) 246. 4. J. Mol. Spec. 195 (1999) 54. 5. Mol. Phys. 96 (1999) 941. 6. J. Mol. Spec. 206 (2001) 83. 7. J. Mol. Spec. 228 (2004) 471. 8. J. Mol. Spec. 251 (2008) 339. 9. J. Atmos. Oceanic Opt. 16 (2003) 172. 10. J. Q. S. R. T. 96 (2005) 139. 11. J. Q. S. R. T. 110 (2009) 533. The bending-rotation approach makes use of Radau Coordinates The bending-rotation approach has been used to fit the new data. It accounts for the anomalous centrifugal distortion and has already been used in many investigations 1-8 and for the MIPAS 9 and HITRAN 10,11 data bases.

10 Line position analysis The data considered in a previous investigation 1 and the 6444 newly measured lines were fitted. 1. Coudert, Wagner, Birk, Baranov, Lafferty, and Flaud, J. Mol. Spec. 251 (2008) 339. 22986 data fitted Unitless Standard deviation is 1.2 336 parameters determined

11 Analysis results for the new data UNC & RMS are in   cm 

12 Residuals plot

13

14 The anomalous centrifugal distortion is accounted for

15 Comparison with other calculations The residuals obtained with the present approach will be compared to those obtained with: Hitran 1 Partridge & Schwenke 2 Barber et al. 3 1. Rothman et al., J. Q. S. R. T. 110 (2009) 533 2. Partridge and Schwenke, J. Chem. Phys. 106 (1997) 4618 3. Barber, Tennyson, Harris, and Tolchenov, M. N. R. A. S. 368 (2006) 1087

16 Residuals plot with Hitran Only  transitions out of . RMS  cm 

17 Comparison with P. & S. Transitions wavenumbers were calculated from the energy levels given by Partridge and Schwenke. 1 1. Partridge and Schwenke, J. Chem. Phys. 106 (1997) 4618

18 Residuals plot with P. & S. levels  transitions. RMS  cm 

19 Residuals plot with P. & S. levels 378 out of 382. RMS  cm 

20 Comparison with Barber et al. Transitions wavenumbers were calculated from the energy levels computed by Barber et al. 1 available in 2. 1. Barber, Tennyson, Harris, and Tolchenov, M. N. R. A. S. 368 (2006) 1087 2. http://www.tampa.phys.ucl.ac.uk/ftp/astrodata/water/BT2

21 Residuals plot with Barber et al. levels  transitions. RMS  cm 

22 RMS values Values are in   cm  Outliers are not taken into account.

23 Line strengths The lines intensity data considered in the previous investigation 1 were re-fitted. Einstein’s A-coefficients were calculated. Several emission spectra were computed. 1. Coudert, Wagner, Birk, Baranov, Lafferty, and Flaud, J. Mol. Spec. 251 (2008) 339.

24 Spectra comparison T  K, Gaussian line profile, Hwhh  cm  Observed Calculated


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