2.2-Boudon - Harvard-Smithsonian Center for Astrophysics
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Transcript 2.2-Boudon - Harvard-Smithsonian Center for Astrophysics
GLOBAL FREQUENCY AND
INFRARED INTENSITY ANALYSIS OF
12CH LINES IN THE 0 – 4800 cm-1
4
REGION
Andrei NIKITIN
Laboratory of Theoretical Spectroscopy, Institute of Atmospheric Optics, Russian Academy of Sciences, 634055 Tomsk, Russia
Vincent BOUDON, Jean-Paul CHAMPION, Michel LOËTE
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 Zürich, CH-8093 Zürich, SWITZERLAND
Linda R. BROWN
Jet 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
Introduction
• 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)
Tetradecad
Icosad
1.0
Triacontad
1.5
Tetracontad
Target = Sun, Altitude = 30 km
Pentacontakaipentad
Intensity / (Solar flux / )
2.0
0.5
0.0
0.8
12000
1.0
1.2
1.4
Wavelength / m
10000
9000
8000
7000
-1
Wavenumber / cm
1.6
6000
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Contents
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
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Present status of CH4 analyses (early 2006)
Polyad / Spectral region
Line positions
Line intensities
Line shapes
1 – Ground state
0–200 cm-1 (> 5.0 m)
Complete analysis,
J ≤ 24
Complete analysis
No 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 N2
3 – Pentad
2200–3300 cm-1 (3.0–4.6 m)
Complete analysis,
J ≤ 18
Complete analysis,
cold bands only
Perturbers:
He, Ar, N2, O2, CH4
4 – Octad
3700–4800 cm-1 (2.0–2.7 m)
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 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
No analysis
Upper polyads
> 7800 cm-1 (< 1.28 m)
No analysis
No analysis
No analysis
Windows
(polyad far wings, all regions)
No analysis
No analysis
No analysis
† J.-C.
Hilico et al., J. Mol. Spectrosc. 208, 1–13 (2001)
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Available 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 !
• 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
- 9th
T Biennal
= 78 HITRAN
K
Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
II. The model
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
The methane molecule
1 2 2 3 2 4
Normal modes of methane:
S4
1
C3
Point group: Td
2
3
4
A1
E
F2
F2
Stretching
Bending
Stretching
Bending
Raman
Raman
IR
IR
2916 cm-1
1533 cm-1
3019 cm-1
1311 cm-1
Definition of polyad Pn:
n 2v1 v2 2v3 v4
Large rotational constant:
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Global fit
The polyads of CH4
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Effective tensorial Hamiltonian
Polyad structure
P3
Systematic tensorial development
P2
Rotation
Coupled rovibrational basis
Vibration
P1
rJ ,nC vCv
P0
Effective Hamiltonian and vibrational extrapolation
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
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
II. Fit of line positions
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Fit details
Total: 16 738 data (MW, IR, Raman – 520 new octad lines from ETH)
Dyad
Pentad
Octad
dRMS
= 1.3 104 cm1, dRMS
= 6.0 104 cm1 dRMS
= 3.5 103 cm1
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Fit 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
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Observed Octad levels (Octad – GS)
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Observed Octad levels (Octad – Dyad)
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
III. Fit of line intensities
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Fit details
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Fit residuals for line intensities
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Dyad intensities
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Pentad intensities
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Octad intensities
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
1.0
0.5
Exp.
0.0
4000
Resol. = 0.001 cm-1
4200
4400
Wavenumber / cm -1
Simulation / This work
Calc.
Experiment / ETH / 78 K
Transmission
Overview of the new ETH spectrum (78 K)
4600
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Simulation / STDS 2005
Comparison with previous results I
Simulation / This work
New Calc.
1.0
Experiment / ETH / 78 K
Transmission
Old Calc. (Hilico et al.)
0.5
Exp.
0.0
4050
4060
4070
4080
Wavenumber / cm -1
4090
4100
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
Simulation / STDS 2005
Comparison with previous results II
Simulation / This work
New Calc.
1.0
Experiment / ETH / 78 K
Transmission
Old Calc. (Hilico et al.)
0.5
Exp.
0.0
4099
4100
4101
4102
4103
Wavenumber / cm -1
4104
4105
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
IV. Perspectives for CH4 spectroscopy
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006
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
Spherical Top Data System
www.u-bourgogne.fr/LPUB/shTDS.html
• Molecular parameter database
• Calculation and analysis programs
• XTDS : Java interface
9th Biennal HITRAN Conference • Harvard-Smithsonian Center for Astrophysics • June 26–28, 2006