Spectral line parameters including line shapes in the 2ν3 Q branch of 12CH4
| Autor: | V. Malathy Devi, Arlan W. Mantz, Syed Ismail, Linda R. Brown, Mary Ann H. Smith, D. Chris Benner, Shanshan Yu, Vincent Boudon, Keeyoon Sung, Timothy J. Crawford |
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| Rok vydání: | 2016 |
| Předmět: |
Physics
Radiation 010304 chemical physics 010504 meteorology & atmospheric sciences Absorption spectroscopy Lorentz transformation 01 natural sciences Atomic and Molecular Physics and Optics Manifold Spectral line Spectral line shape symbols.namesake Nuclear magnetic resonance Quadratic equation 0103 physical sciences symbols Atomic physics Spectroscopy Mixing (physics) 0105 earth and related environmental sciences Line (formation) |
| Zdroj: | Journal of Quantitative Spectroscopy and Radiative Transfer. 177:152-169 |
| ISSN: | 0022-4073 |
| DOI: | 10.1016/j.jqsrt.2015.12.009 |
| Popis: | In this study, we report the first experimental measurements of spectral line shape parameters (self- and air-broadened Lorentz half-widths, pressure-shifts, and line mixing (via off-diagonal relaxation matrix elements) coefficients and their temperature dependences, where appropriate) for transitions in the 2ν 3 Q branch manifolds, Q(11)–Q(1) of methane ( 12 CH 4 ), in the 5996.5–6007-cm −1 region. The analysis included 23 high-resolution, high signal-to-noise laboratory absorption spectra recorded with the Bruker IFS-125HR Fourier transform spectrometer (FTS) at JPL. The experimental data were obtained using 12 C-enriched 12 CH 4 and dilute mixtures of 12 CH 4 in dry air in the 130–296 K range using a room-temperature long path absorption cell and, two custom-built coolable cells. In the analysis, an interactive multispectrum fitting software was employed where all the 23 spectra (11 self-broadened and 12 air-broadened) were fit simultaneously. By carefully applying reasonable constraints to the parameters for severely blended lines, we were able to determine a self-consistent set of broadening, shift and line mixing (relaxation matrix coefficients) parameters for CH 4 –CH 4 and CH 4 –air collisions. In the majority of cases, a quadratic speed dependence parameter common for all transitions in each Q( J ) manifold was determined. However, temperature dependences of the Q branch line mixing parameter could not be determined from the present data. Since no other experimental line shape measurements have been reported for this Q-branch, the present results are compared to available values in the HITRAN2012 database. |
| Databáze: | OpenAIRE |
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