HDO and D 2 O long path spectroscopy: Ongoing work of the Brussels-Reims Team.

Transcription

1 HDO and D 2 O long path spectroscopy: Ongoing work of the Brussels-Reims Team. Ludovic Daumont Groupe de Spectroscopie Moléculaire et Atmosphérique UMR CNRS 6089 Université de Reims Champagne Ardenne Reims, France

2 Workgroup involved in water vapor absorption measurements L. Daumont, (M-F. Mérienne), L.Regalia-Jarlot, Vl. Tyuterev, A. Jenouvrier Groupe de Spectrométrie Moléculaire et Atmosphérique Université de Reims Champagne-Ardenne. Reims, France S. Fally, P-F. Coheur, C. Clerbaux, M. Bach, M. Carleer Unité de Spectroscopie Atmosphérique Service de Chimie Quantique et Photophysique Université Libre de Bruxelles. Brussels, Belgium A-C. Vandaele, C. Hermans Institut d Aéronomie Spatiale de Belgique. Bruxelles, Belgique A. Campargue Laboratoire de Spectrométrie Physique Université de Grenoble, Saint-Martin-d Hères, France S. Mikhailenko, O. Naumenko, S. Tachkun Institut of Atmospheric Optics, Tomsk, Russia J.Tennyson Department of Physics and Astronomy, University College, England

3 Integrated absorption cross sections ΣS(296K) cm/molec HITRAN E-17 1E-22 1E-17 1E-22 1E-17 1E-22 HOD 7250 cm -1 H 17 2 O cm -1 H 18 2 O cm -1 1E-17 1E-22 H 2 16 O cm -1 1E Band Centers cm -1

4 Experimental setup Cell (50 m base long ) Bruker FTS IFS 120M (ULB or IASB) Cooling or heating system Laboratory made Spectrometer Temperature controlled Cell (5 m base long ) Sources Xe, W, Globar

5 Experimental setup

6 experimental conditions for HDO D 2 O spectra Absorption path: 600 m Resolution: down to 0.03 cm -1 (30 cm MOPD) Spectral range: cm -1 H 2 O + D 2 O mixtures ( P tot 10 hpa ) Room temperature: T 293 K Wavenumber calibration: I 2 ( table of Gesternkorn )

7 Vis-NIR water absorption spectra diode GaP Xe Source diode Si Xe Source diode Si W Source 7n+d 7n 6n+d 5n+d 5n 4n+d 3n 2n+d 8n 6n 4n 3n+d

8 IR Absorption spectra diode Si W Source InSb W Source InSb W Source 2n+d 2n n+d n

9 Intensity (a. u.) Vis-NIR spectral range: Subtraction of the H 2 O lines Observed (H 2 O & HOD) Simulated (H 2 O) Subtracted (only HOD lines left) Wavenumber (cm -1 )

10 NIR spectral range: H2O, HDO and D2O H2O pure Path: 600 m, P: 13 hpa, Resol.: 0.03 cm-1 A 2.4 HDO+D2O 1.9 A/C H2O:3.1% HDO:22.7% D2O:74.2 % H2O B C/B H2O:16.5 % HDO:49.8 % D2O:33.7 % C D2O H2O+HDO

11 Partial pressures: IR region Total Pressures: Baratron P tot 1=P P P P tot 2=P P P Use of BR list for H 2 16 O partial pressures (from natural H 2 O spectra) P tot 1=P P P P tot 2=P P P Isotopologue assignement => Spectra Ratios Line surface measurements => with the good molar mass Determination of the mean Surface ratios for HDO and D 2 O r 1 =P 126 1/P r 2 =P 226 1/P Calculation of partial pressures and line intensities

12 IR region: H 2 0, D 2 0 and HDO line intensities 1.2E-23 1E-23 H 2 0 8E-24 6E-24 4E-24 2E E E-23 8E-24 D 2 O 6E-24 4E-24 2E E-23 1E-23 8E-24 HDO 6E-24 4E-24 * * * * * * 2E-24 *

13 IR region: HDO line assignement Based on the new calculation of Partridge and Schwenke for both positions and intensities Still under progress in this region ( cm -1 ) In the present work HDO cm -1 region: 4380 observed lines mainly from 2ν+δ, 3ν and 3ν+δ polyads 5200 assignments An integrated intensity of cm molec -1 for this region D 2 O: cm -1 region: 2160 observed lines mainly from 3ν+δ, 4ν, 4ν+δ and 5ν polyads 2596 assignements An integrated intensity of cm molec -1 for this region

14 Example of a subband: ν 1 +2 ν 3 ΔK a =0 K a =0 2 S(obs) S(PS) 1 ΔK c =-1 ΔK c =1 Average: 0.95 S (10-24 cm molec -1 ) ν obs -ν calc (cm -1 ) Wavenumber cm -1

15 S (10-24 cm molec -1 ) Example II of a subband: ν 1 +2 ν 3 ΔK a =1 K a =0, ΔK c =1 2 S(obs) S(PS) 1 Average: 0.97 ν obs -ν calc (cm -1 )

16 Global comments Entire spectral range Better agreement between different spectral ranges. A lot of weak lines Better atmospheric spectra simulation. Convergence of the theory towards the experimental needs. The discrete bands can now be taken off to study the underlying continuum. A lot of unresolved blended lines Water vapor pressure measurement still difficult. Longer absorption paths needed to compare to atmospheric horizontal (10-20 km) measurement at sea level!

17 Available linelists and intensities web site from ULB - HITRAN GEISA Continuing work IUPAC - Water vapor database constitution for all the isotopologues (experience and theory) HOD- D 2 O - Measures down to 4200 cm -1 (spectra being processed) H 2 O - Analysis of the IR spectra ( cm -1 ) H 2 18 O -..

18 IR Absorption spectra diode Si W Source InSb W Source InSb W Source 2n+d 2n n+d n

19 HDO and D 2 O long path spectroscopy: On going work of the Brussels-Reims Team. The End