SELF- AND AIR-BROADENED LINE SHAPE PARAMETERS OF 12CH4 : 4500-4620 CM−1

Devi, V. Malathy

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https://hdl.handle.net/2142/50833 Copy

Description

Title

SELF- AND AIR-BROADENED LINE SHAPE PARAMETERS OF 12CH4 : 4500-4620 CM−1

Author(s)

Devi, V. Malathy

Contributor(s)

• Predoi-Cross, Adriana
• Mantz, Arlan
• Smith, Mary Ann H.
• Crawford, Timothy J.
• Brown, Linda
• Sung, Keeyoon
• Benner, D. Chris

Issue Date

2014-06-17

Keyword(s)

Atmospheric science

Abstract

Accurate knowledge of spectral line shape parameters is important for infrared transmission and radiance calculations in the terrestrial atmosphere. We report the self- and air-broadened Lorentz widths, shifts and line mixing coefficients along with their temperature dependences for methane absorption lines in the 2.2 $\mu$m spectral region. For this, we obtained a series of high-resolution, high S/N spectra of 99.99$\%$ $^{12}$C-enriched samples of pure methane and its dilute mixtures in dry air at cold temperatures down to 150 K using the Bruker IFS 125HR Fourier transform spectrometer at JPL. The coolable absorption cell had an optical path of 20.38 cm and was specially built to reside inside the sample compartment of the Bruker FTS\footnote{K.~Sung, A.~W.~Mantz, L.~R.~Brown, \textit{et al.}, \textit{J. Mol. Spectrosc.} \underline{\textbf{162}} (2010) 124-134.}. The 13 spectra used in the analysis consisted of seven pure $^{12}$CH$_4$ spectra at pressures from 4.5 to 169 Torr and six air-broadened spectra with total sample pressures of 113-300 Torr and methane volume mixing ratios between 4 and 9.7$\%$. These 13 spectra were fit simultaneously using the multispectrum least-squares fitting technique\footnote{D.~C.~Benner, C.~P.~Rinsland, V.~Malathy Devi, M.~A.~H.~Smith and D.~Atkins, \textit{JQSRT} \underline{\textbf{53}} (1995) 705-721.}. The results will be compared to existing values reported in the literature.\footnote{Research described in this paper was performed at Connecticut College, the College of William and Mary, NASA Langley Research Center and the Jet Propulsion Laboratory, California Institute of Technology, under contracts and cooperative agreements with the National Aeronautics and Space Administration.}

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

English

Permalink

http://hdl.handle.net/2142/50833

DOI

https://doi.org/10.15278/isms.2014.TI16

Copyright and License Information

Copyright 2014 by the authors. Licensed under a Creative Commons Attribution 4.0 International License. http://creativecommons.org/licenses/by/4.0/

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