BROADENING AND SHIFTS OF $CH_{4}$ LINES IN THE $\nu_{4}$ BAND AT LOW TEMPERATURES
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Date
1990
Journal Title
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Publisher
Ohio State University
Abstract
We have recorded a series of high-resolution absorption spectra of methane broadened by dry air and by $N_{2}$ at low temperatures using the McMath Fourier transform spectrometer at the National Solar Observatory on Kitt Peak. The spectra cover a wavenumber range from approximately $500 cm^{-2}$ to $1500 cm^{-2}$ at a resolution of $0.01 cm^{-2}$. A 50 cm double-walled Pyrex absorption cell cooled by circulating chilled ethanol enabled us to obtain spectra over a temperature range from $2^{\circ}C$ to $-63^{\circ}C$. These spectra have been analyzed to determine pressure broadening and line shift coefficients at low temperatures for a number of lines in the $\nu_{4}$ fundamental band of $^{12} CH_{4}$. These values, along with previously-determined room-temperature $coefficients^{1}$, have been used to examine the temperature-dependence of the air- and $N_{2}$-broadening and shift coefficients for these $CH_{4}$ lines
Description
1C.P. Rinsland, V. Malathy Devi, M. A. H. Smith. and D. C. Benner, Appl. Opt. 27, 631-651 (1988).
Author Institution: Atmospheric Sciences Division, Mail Stop 401A. NASA Langley Research Center; Physics Department, College of William and Mary.
Author Institution: Atmospheric Sciences Division, Mail Stop 401A. NASA Langley Research Center; Physics Department, College of William and Mary.