Transcript Benner890CH4MSS2011.ppt

The 4ν 3 Spectral Region of Methane
D. Chris Benner, V Malathy Devi and Jennifer Hays
College of William and Mary
James J. O'Brien, S. Shaji
University of Missouri, St. Louis
V Malathy Devi
College of William and Mary
Philip T. Spickler, Christopher P. Houck,
Jessica A. Coakley, Kasie J. Haga and Justin D. Dolph
Bridgewater College
Adel and Slipher, Phys. Rev. 46, 902 (1934)
METHANE
Polyads: 0 – 14000 cm-1
2.3 μm
3.3 μm
7.6 μm
From Boudon et al.
 Global fit 
1.7 μm
Conclusions
For outer solar system simulations, the bands of methane near 1μm are tractabl
for line by line analysis.
Positions, Intensities and lower state energies are being measured for the band
complex near 890 nm for temperatures below about 160K. About 1/3 of this ban
is complete with about 3500 spectral lines measured so far. Another 1/3 has a
tentative line list. The rest of the band will be completed within months.
Simulations of this band are possible with these data as a function of temperatu
pressure, path length, mixing ratio and broadener.
For lower pressures useful structure is seen down to the Doppler half width of th
lines, that is to about 0.01 cm-1. For higher pressures structure is limited by the
Lorentz width. Lines are, on average, 0.05 cm-1 apart.
Band models are no longer necessary for this band.
Modeling of atmospheres with layers of different pressures and
temperatures is now straightforward with line by line parameters.
Modeling of scattering in the atmospheres is possible with the
line by line spectral parameters. Since scattering is generally
stronger at shorter wavelengths, this adds significant new
information to farther infrared studies.