1. 9th Biennal HITRAN Conference Harvard-Smithsonian Center for Astrophysics June 26–28, 2006 GLOBAL FREQUENCY AND INFRARED INTENSITY ANALYSIS OF 12 CH 4 LINES IN THE 0 – 4800 cm -1 REGION Andrei NIKITIN Laboratory of Theoretical Spectroscopy, Institute of Atmospheric Optics, Russian Academy of Sciences, 634055 Tomsk, Russia Vincent BOUDON, Jean-Paul CHAMPION, Michel LO Ë TE Laboratoire de Physique de l’Université de Bourgogne – CNRS UMR 5027, 9 Av. A. Savary, BP 47870, F-21078 DIJON, FRANCE Sieghard ALBERT, Sigurd BAUERECKER, Martin QUACK Physical Chemistry, ETH Z ü rich, CH-8093 Z ü rich, SWITZERLAND Linda R. BROWN Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109, USA

2. 9th Biennal HITRAN Conference Harvard-Smithsonian Center for Astrophysics June 26–28, 2006 Introduction CH 4 is an important greenhouse gas and a major constituent of planetary atmospheres Need for a precise modeling of excited methane states: Earth’s atmosphere, planets (Titan, …), brown dwarfs, … EarthTitanGiant planetsBrown dwarfs Experiments & in situ data far in advance compared to theory !!!

3. 9th Biennal HITRAN Conference Harvard-Smithsonian Center for Astrophysics June 26–28, 2006 DISR spectrum of Titan (Huygens / ESA)

4. 9th Biennal HITRAN Conference Harvard-Smithsonian Center for Astrophysics June 26–28, 2006 Contents I.CH 4 : Present status and available data II.The model III.Fit of line positions IV.Fit of line intensities V.Perspectives for CH 4 spectroscopy

5. 9th Biennal HITRAN Conference Harvard-Smithsonian Center for Astrophysics June 26–28, 2006 I. CH 4 : Present status and available data

6. 9th Biennal HITRAN Conference Harvard-Smithsonian Center for Astrophysics June 26–28, 2006 Present status of CH 4 analyses (early 2006) † J.-C. Hilico et al., J. Mol. Spectrosc. 208, 1–13 (2001) Polyad / Spectral regionLine positionsLine intensitiesLine shapes 1 – Ground state 0–200 cm -1 (> 5.0  m) Complete analysis, J ≤ 24 Complete analysisNo analysis 2 – Dyad 1000–1800 cm -1 (5.6–10.0  m) Complete analysis, J ≤ 23 Complete analysis, with some hot bands Perturbers: He et N 2 3 – Pentad 2200–3300 cm -1 (3.0–4.6  m) Complete analysis, J ≤ 18 Complete analysis, cold bands only Perturbers: He, Ar, N 2, O 2, CH 4 4 – Octad 3700–4800 cm -1 (2.0–2.7  m) Perfectible analysis, J ≤ 16 d RMS = 0.041 cm -1 † Perfectible analysis, cold bands only d RMS = 15.6 % † No analysis 5 – Tetradecad 5400–6300 cm -1 (1.6–1.9  m) Incomplete analysis, J ≤ 10 Partial analysis, cold bands only No analysis 6 – Icosad 6600–7700 cm -1 (1.3 – 1.5  m) Very partial analysis of 1 band among 20 No analysis Upper polyads > 7800 cm -1 (< 1.28  m) No analysis Windows (polyad far wings, all regions) No analysis

7. 9th Biennal HITRAN Conference Harvard-Smithsonian Center for Astrophysics June 26–28, 2006 Available CH 4 data used in this work Microwave line positions (Z ü rich, Kiel, Lille) Infrared (FTIR) line positions and intensities (KPNO & other sources) Raman line positions (Madrid, Dijon) Availability of new experimental data (2005–2006): New intensities measured at KPNO New high-resolution spectra recorded at ETH Z ü rich: - Bruker IFS 125 HR Z ü rich Prototype (ZP2001) - Instrumental bandwidth ≤ 0.001 cm -1, unapodized - T = 78 K NEW !

8. 9th Biennal HITRAN Conference Harvard-Smithsonian Center for Astrophysics June 26–28, 2006 II. The model

9. 9th Biennal HITRAN Conference Harvard-Smithsonian Center for Astrophysics June 26–28, 2006 The methane molecule Normal modes of methane: Definition of polyad P n : S4S4 C3C3 Point group: T d 1 2 3 4 A1A1 EF2F2 F2F2 StretchingBendingStretchingBending Raman IR 2916 cm -1 1533 cm -1 3019 cm -1 1311 cm -1 Large rotational constant:

10. 9th Biennal HITRAN Conference Harvard-Smithsonian Center for Astrophysics June 26–28, 2006 The polyads of CH 4  Global fit 

11. 9th Biennal HITRAN Conference Harvard-Smithsonian Center for Astrophysics June 26–28, 2006 Effective tensorial Hamiltonian Systematic tensorial development Effective Hamiltonian and vibrational extrapolation Coupled rovibrational basis Rotation Vibration Polyad structure P0P0 P1P1 P2P2 P3P3

12. 9th Biennal HITRAN Conference Harvard-Smithsonian Center for Astrophysics June 26–28, 2006 Vibrational extrapolation examples Effective Hamiltonian for the Octad:  Simultaneous fit of GS, Dyad, Pentad and Octad Effective dipole moment for Pentad–Dyad transitions:  Simultaneous fit of Dyad–GS and Pentad–Dyad intensities

13. 9th Biennal HITRAN Conference Harvard-Smithsonian Center for Astrophysics June 26–28, 2006 II. Fit of line positions

14. 9th Biennal HITRAN Conference Harvard-Smithsonian Center for Astrophysics June 26–28, 2006 Fit details

15. 9th Biennal HITRAN Conference Harvard-Smithsonian Center for Astrophysics June 26–28, 2006 Fit residuals for line positions MW IR IR + Raman IR

16. 9th Biennal HITRAN Conference Harvard-Smithsonian Center for Astrophysics June 26–28, 2006 Calculated Octad levels and mixings

17. 9th Biennal HITRAN Conference Harvard-Smithsonian Center for Astrophysics June 26–28, 2006 Observed Octad levels (Octad – GS)

18. 9th Biennal HITRAN Conference Harvard-Smithsonian Center for Astrophysics June 26–28, 2006 Observed Octad levels (Octad – Dyad)

19. 9th Biennal HITRAN Conference Harvard-Smithsonian Center for Astrophysics June 26–28, 2006 III. Fit of line intensities

20. 9th Biennal HITRAN Conference Harvard-Smithsonian Center for Astrophysics June 26–28, 2006 Fit details

21. 9th Biennal HITRAN Conference Harvard-Smithsonian Center for Astrophysics June 26–28, 2006 Fit residuals for line intensities

22. 9th Biennal HITRAN Conference Harvard-Smithsonian Center for Astrophysics June 26–28, 2006 Dyad intensities

23. 9th Biennal HITRAN Conference Harvard-Smithsonian Center for Astrophysics June 26–28, 2006 Pentad intensities

24. 9th Biennal HITRAN Conference Harvard-Smithsonian Center for Astrophysics June 26–28, 2006 Octad intensities

25. 9th Biennal HITRAN Conference Harvard-Smithsonian Center for Astrophysics June 26–28, 2006 Overview of the new ETH spectrum (78 K) Calc. Exp. Resol. = 0.001 cm -1

26. 9th Biennal HITRAN Conference Harvard-Smithsonian Center for Astrophysics June 26–28, 2006 Comparison with previous results I Exp. New Calc. Old Calc. (Hilico et al.)

27. 9th Biennal HITRAN Conference Harvard-Smithsonian Center for Astrophysics June 26–28, 2006 Comparison with previous results II Exp. New Calc. Old Calc. (Hilico et al.)

28. 9th Biennal HITRAN Conference Harvard-Smithsonian Center for Astrophysics June 26–28, 2006 IV. Perspectives for CH 4 spectroscopy

29. 9th Biennal HITRAN Conference Harvard-Smithsonian Center for Astrophysics June 26–28, 2006 CH 4 spectroscopy: What next ? Continue the global fit approach Next step: the Tetradecad (5400 – 6300 cm -1 ) Add new data (positions & intensities, cold & hot bands) Icosad, … Methane windows (high-J, far wings) for planetary atmospheres Hot methane (combustions, brown dwarfs, …) Isotopologues: 13 CH 4, 12 CH 3 D, … HITRAN update with the new results

30. 9th Biennal HITRAN Conference Harvard-Smithsonian Center for Astrophysics June 26–28, 2006 The STDS database Spherical Top Data System www.u-bourgogne.fr/LPUB/shTDS.html Molecular parameter database Calculation and analysis programs XTDS : Java interface