Transcript Benner890nmCH4.pptx

LINE BY LINE SPECTRAL
PARAMETERS IN THE 4nu3
SPECTRAL REGION OF METHANE
D. CHRIS BENNER, V. MALATHY DEVI,
College of William and Mary
J. J. O’BRIEN, S. SHAJI,
University of Missouri - St. Louis
P. T. SPICKLER, C. P. HOUCK, J. A. COAKLEY,
J. DOLPH and K. RANKIN,
Bridgewater College
Planetary History of the Visible and Near IR Methane bands
H. C. Vogel, Ap J 1, 273 (1895). Photography of the bands
V. M. Slipher, Lowell Obs Bull 13 (1904). Gas lighter than H2 suggested for Neptune
V. M. Slipher, Ap J 26, 59 (1907). Bands absent in rings of Saturn.
V. M. Slipher, Lowell Obs Bull 42 (1909). Spectroscopy extended to 700 nm.
Adel and Slipher, Phys Rev. 46, 902 (1934). Absorber might be methane.
Herzberg, 1940s. Identifies the absorber as methane via lab spectra.
Kuiper, late 1940s. Discovers methane in atmosphere of Titan.
Benner and Fink, Icarus (1980). Clearly showed the 890 nm band on Pluto.
Adel and Slipher, Phys Rev. 46, 902 (1934).
Benner, Dissertation (1979).
Spectrum Details
Spectral Range: 10925 to 11500 cm-1
Resolution: 0.01 cm-1 HWHM
Temperatures: 99, 131 and 161 K
Doppler Widths: ~0.01 cm-1 HWHM
Pressures: 0.12-7.13 Torr
Path Length: 3.14-5.65 km
Number of lines measured: 11 200+
Summary
Positions, intensities and E” measured for 11200+ lines of methane at 890 nm
Lorentz widths for N2, air, H, He and self broadening are provided
Pressure shifts for N2, air, H, He and self broadening are provided
Simulations of this region are possible at outer solar system temperatures
Non homogeneous atmospheres can be simulated (not band models)
Scattering models can now be calculated (could not be done with band models)
Higher resolution increases detectability of the band dramatically
Pluto’s 890 nm feature is almost entirely due to ice, not gas