СО2 absorption in band wings
T.E. Klimeshina, T.M. Petrova, O.B. Rodimova, A.A. Solodov, A.M. Solodov
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, 1, Academician Zuev square, Tomsk, 634021, Russia
Keywords: continuum absorption, carbon dioxide, self-broadening, spectral line wings
Abstract
The CO2 absorption was measured in the 7 000 and 8 000 cm–1 region. Calculations of the absorption coefficient were performed using the asymptotic line wing shape theory. Line contour parameters were associated with the classical potential governing the center–of–mass motion and with the quantum potential of two interacting molecules. They were found from fitting the calculated absorption coefficient to experiment. The calculated coefficient values agree well with the measured data. According to the line wing theory the absorption in the band wings is due to the wings of the strong lines of adjacent band. With these assumptions experimental and calculated data on the CO2 absorption coefficient in the band wings in the 7 000 and 8 000 cm–1 regions can provide information on the line shape at frequency detunings from several tens to several hundreds of half-widths. The results obtained support the hypothesis that line shape parameters in the line wings related to the transitions with the same initial state appear to be close to each other. Deviations from the Lorentzian contour are defined for a set of CO2 bands. The former are found to be different for the wings of different bands.
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