High-Lying Rotational Levelsof Water obtained by FIREmission Spectroscopy

L. H. Coudert,a M.-A. Martin,b O. Pirali,b

D. Balcon,b and M. Vervloetb

aLISA, CNRS/Universities Paris Est and Paris Diderot, Créteil, France

bLigne AILES - Synchrotron SOLEIL, Gif-sur-Yvette, France

Why High-lying Rotational levels?

Spectrum of water at high temperature

Water at a temperature of K has been detectedaround supergiant stars.1

Hot water is expected to be found in extrasolar gas-giant planetslike HD 209458b2-3 characterized by a temperature of K.

1T. Tsuji, ApJ. 540 (2000) L992http://www.nasa.gov/centers/godard/new/topstory/2007/cloudy_world.html3http://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

BrukerIFS 125

Radio Frequencydischarge

Fourier transform interferometer of the Ailes beam line at Soleil

Radio frequency discharge

F = 13.6 MHzPower = 1000 WPressures = 10 and 15 TorrTemperature 1000 K

Faraday cage

Pyrex cell

Fan

Low pressure spectrum

High pressure spectrum

The assigned lines

Up to the 2nd triad, number of assigned lines is

There are also lines for the first hexad

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 investigations1-8 and for the MIPAS9 and HITRAN10,11 data bases.

Line position analysis

The data considered in a previous investigation1 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

Analysis results for the new data

UNC & RMS are in cm

Residuals plot

Residuals plot

Residuals plot

The anomalous centrifugaldistortion is accounted for

Comparison with other calculations

The residuals obtained with the present approachwill be compared to those obtained with:

•Hitran1

•Partridge & Schwenke2

•Barber et al.3

1. Rothman et al., J. Q. S. R. T. 110 (2009) 5332. Partridge and Schwenke, J. Chem. Phys. 106 (1997) 46183. Barber, Tennyson, Harris, and Tolchenov, M. N. R. A. S. 368 (2006) 1087

Residuals plot with Hitran

Only transitions out of . RMScm

Comparison with P. & S.

Transitions wavenumbers were calculated from the energylevels given by Partridge and Schwenke.1

1. Partridge and Schwenke, J. Chem. Phys. 106 (1997) 4618

Residuals plot with P. & S. levels

transitions. RMScm

Residuals plot with P. & S. levels

378 out of 382. RMScm

Comparison with Barber et al.

Transitions wavenumbers were calculated from the energylevels computed by Barber et al.1 available in 2.

1. Barber, Tennyson, Harris, and Tolchenov, M. N. R. A. S. 368 (2006) 10872. http://www.tampa.phys.ucl.ac.uk/ftp/astrodata/water/BT2

Residuals plot with Barber et al. levels

transitions. RMScm

RMS values

Values are in cm

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

TK, Gaussian line profile, Hwhhcm

Observed

Calculated