9th Biennal HITRAN Conference Harvard-Smithsonian Center for Astrophysics June 26–28, 2006 GLOBAL...
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9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
GLOBAL FREQUENCY AND INFRARED INTENSITY ANALYSIS OF
12CH4 LINES IN THE 0 – 4800 cm-1 REGION
GLOBAL FREQUENCY AND INFRARED INTENSITY ANALYSIS OF
12CH4 LINES IN THE 0 – 4800 cm-1 REGION
Andrei NIKITINLaboratory of Theoretical Spectroscopy, Institute of Atmospheric Optics, Russian Academy of Sciences, 634055 Tomsk, Russia
Vincent BOUDON, Jean-Paul CHAMPION, Michel LOËTELaboratoire 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 QUACKPhysical Chemistry, ETH Zürich, CH-8093 Zürich, SWITZERLAND
Linda R. BROWNJet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109, USA
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
IntroductionIntroduction• CH4 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, …
Earth Titan Giant planets Brown dwarfs
• Experiments & in situ data far in advance compared to theory !!!
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
DISR spectrum of Titan (Huygens / ESA)DISR spectrum of Titan (Huygens / ESA)2.0
1.5
1.0
0.5
0.01.61.41.21.00.8
/ Wavelengthμm
12000 10000 9000 8000 7000 6000 / Wavenumber cm-1
= , = 30 Target Sun Altitude km
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
ContentsContents
I. CH4: Present status and available data
II. The model
III. Fit of line positions
IV. Fit of line intensities
V. Perspectives for CH4 spectroscopy
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
I. CH4: Present status and available data
I. CH4: Present status and available data
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Present status of CH4 analyses (early 2006)Present status of CH4 analyses (early 2006)
† J.-C. Hilico et al., J. Mol. Spectrosc. 208, 1–13 (2001)
Polyad / Spectral region Line positions Line intensities Line shapes
1 – Ground state
0–200 cm-1 (> 5.0 μm)
Complete analysis,
J ≤ 24Complete analysis No analysis
2 – Dyad
1000–1800 cm-1 (5.6–10.0 μm)
Complete analysis,
J ≤ 23Complete analysis,
with some hot bands
Perturbers:
He et N2
3 – Pentad
2200–3300 cm-1 (3.0–4.6 μm)
Complete analysis,
J ≤ 18Complete analysis,
cold bands only
Perturbers:
He, Ar, N2, O2, CH4
4 – Octad
3700–4800 cm-1 (2.0–2.7 μm)
Perfectible analysis,
J ≤ 16
dRMS = 0.041 cm-1 †
Perfectible analysis, cold bands only
dRMS = 15.6 % †
No analysis
5 – Tetradecad
5400–6300 cm-1 (1.6–1.9 μm)
Incomplete analysis,
J ≤ 10Partial analysis, cold
bands onlyNo analysis
6 – Icosad
6600–7700 cm-1 (1.3 – 1.5 μm)Very partial analysis of 1 band among 20
No analysis No analysis
Upper polyads
> 7800 cm-1 (< 1.28 μm)No analysis No analysis No analysis
Windows
(polyad far wings, all regions)No analysis No analysis No analysis
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Available CH4 data used in this workAvailable CH4 data used in this work• Microwave line positions (Zürich, 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 Zürich:
- Bruker IFS 125 HR Zürich Prototype (ZP2001)- Instrumental bandwidth ≤ 0.001 cm-1, unapodized- T = 78 K
NEW !
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
II. The modelII. The model
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
The methane moleculeThe methane molecule
Normal modes of methane: ν1 ≈ 2ν 2 ≈ ν 3 ≈ 2ν 4
n =2v1 + v2 + 2v3 + v4Definition of polyad Pn:
S4
C3
Point group: Td
ν1 ν2 ν3 ν4
A1 E F2 F2
Stretching Bending Stretching Bending
Raman Raman IR IR
2916 cm-1 1533 cm-1 3019 cm-1 1311 cm-1
Large rotational constant:
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
The polyads of CH4The polyads of CH4
G
lob
al f
it
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Effective tensorial HamiltonianEffective tensorial Hamiltonian
Systematic tensorial development
Effective Hamiltonian and vibrational extrapolation
ΨrJ ,nC( ) ⊗Ψ v
Cv( )⎡⎣
⎤⎦
Γ( )
Coupled rovibrational basisRotation Vibration
Polyad structure
P0
P1
P2
P3
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Vibrational extrapolation examplesVibrational 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
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
II. Fit of line positionsII. Fit of line positions
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Fit detailsFit details
Total: 16 738 data (MW, IR, Raman – 520 new octad lines from ETH)
dRMSDyad = 1.3×10−4 cm−1, dRMS
Pentad = 6.0 ×10−4 cm−1 dRMSOctad = 3.5 ×10−3 cm−1
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Fit residuals for line positionsFit residuals for line positions
MW MW MW IR
IR + Raman IR IR IR
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Calculated Octad levels and mixings Calculated Octad levels and mixings
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Observed Octad levels (Octad – GS) Observed Octad levels (Octad – GS)
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Observed Octad levels (Octad – Dyad) Observed Octad levels (Octad – Dyad)
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
III. Fit of line intensitiesIII. Fit of line intensities
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Fit detailsFit details
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Fit residuals for line intensitiesFit residuals for line intensities
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Dyad intensitiesDyad intensities
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Pentad intensitiesPentad intensities
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Octad intensitiesOctad intensities
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Overview of the new ETH spectrum (78 K)Overview of the new ETH spectrum (78 K)
1.0
0.5
0.04600440042004000
Wavenumber / cm-1
Calc.
Exp.
Resol. = 0.001 cm-1
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Comparison with previous results IComparison with previous results I
1.0
0.5
0.0410040904080407040604050
Wavenumber / cm-1
Exp.
New Calc.
Old Calc. (Hilico et al.)
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Comparison with previous results IIComparison with previous results II
1.0
0.5
0.04105410441034102410141004099
Wavenumber / cm-1
Exp.
New Calc.
Old Calc. (Hilico et al.)
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
IV. Perspectives for CH4 spectroscopyIV. Perspectives for CH4 spectroscopy
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
CH4 spectroscopy: What next ?CH4 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: 13CH4, 12CH3D, …
• HITRAN update with the new results
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
The STDS database
The STDS database
Spherical Top Data System
www.u-bourgogne.fr/LPUB/shTDS.html
• Molecular parameter database
• Calculation and analysis programs
• XTDS : Java interface