Transcript h2o_coudert.ppt

Far-Infrared Emission
Spectroscopy of Rovibrationaly
Excited Water Vapor
M.-A. Martin,a O. Pirali,a D. Balcon,a
M. Vervloet,a and L. H. Coudertb
aLigne AILES
bLISA,
- Synchrotron SOLEIL, Gif-sur-Yvette, France
CNRS/Universities Paris Est and Paris Diderot, Créteil, France
Why High-lying Rotational levels?
Spectrum of water at high temperature
Water at a temperature of 1500 K has been detected
around supergiant stars.1
Hot water is expected to be found in extrasolar gas-giant planets
like HD 209458b2-3 characterized by a temperature of 1500 K.
1T.
Tsuji, ApJ. 540 (2000) L99
2http://www.nasa.gov/centers/godard/new/topstory/2007/cloudy_world.html
3http://www.nasa.gov/vision/universe/newworlds/Osiris_leaks.html
Overview
• The new experimental data
• The line position analysis
• The data set
• Results
• Comparison with other data bases
• Line strength comparison
Experimental setup
Bruker
IFS 125
Radio Frequency
Fourier transform interferometer of the Ailes beam line at Soleil
discharge
Radio frequency discharge
Faraday cage
Fan
Pyrex cell
F = 13.6 MHz
Power = 1000 W
Pressures = 10 and 15 Torr
Temperature  1000 K
Low pressure spectrum
1249  1138 (000)
A
660  550 (000)
853  744 (001)
High pressure spectrum
1212,1  1111,0 (001)
A
1210,3  1192 (000)
The assigned lines
Up to the 2nd triad, number of assigned lines is 6444
There are also lines for the first hexad
The theoretical approach
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 investigations1-8
and for the MIPAS9 and HITRAN10,11
data bases.
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.
Line position analysis
The data considered in a previous investigation1 and the
6444 newly measured lines were fitted.
22986 data fitted
Unitless Standard deviation is 1.2
336 parameters determined
1. Coudert, Wagner, Birk, Baranov, Lafferty, and Flaud, J. Mol. Spec. 251 (2008) 339.
Analysis results for the new data
UNC & RMS are in 10-3 cm-1
Residuals plot
Residuals plot
Residuals plot
The anomalous centrifugal
distortion is accounted for
Comparison with other calculations
The residuals obtained with the present approach
will be compared to those obtained with:
•Hitran1
•Partridge & Schwenke2
•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
Residuals plot with Hitran
Only 265 transitions out of 590. RMS = 0.0006 cm-1
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
Residuals plot with P. & S. levels
529 transitions. RMS = 0.015 cm-1
Residuals plot with P. & S. levels
378 out of 382. RMS = 0.02 cm-1
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
Residuals plot with Barber et al. levels
528 transitions. RMS = 0.049 cm-1
RMS values
Values are in 10-3 cm-1
Outliers are not taken into account.
Line strengths
The lines intensity data considered in the previous
investigation1 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.
Spectra comparison
Observed
Calculated
T = 1000 K, Gaussian line profile, Hwhh = 0.007 cm-1