We propose a new empirical method of band shape calculations which takes into account line mixing effects. The proposed shape is based on the strong collision model with attenuated interbranch coupling. Apart from the conventional set of spectral line parameters one needs only one additional parameter to account for line mixing effects in band profile calculations. This parameter depends on the perturbing gas type. It is the same for all molecular infrared absorption bands. The new shapes are shown to be successful in representing the measured absorption bands of CO2 in nitrogen (v2, v3, v2 + 2v3, 2v2 − v2, and 2v1 − v2) and the 3.6 μm band of O3 in nitrogen.
Papers with the following subject areas are suitable for publication in the Journal of Quantitative Spectroscopy and Radiative Transfer:
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Line mixing effects have been observed in absorption spectra recorded, at room temperature, with a Fourier spectrometer. They concern the Q branches of the v1+v2 band of N2O, centered at 1880.2 cm−1 and of the (1110)<--(0220) band of CO2, centered at 740.8 cm−1. For the N2O spectra, the gas was pure and its pressure has been raised up to more than 6 atm. The CO2 spectra were registered with a total gas pressure below 1 atm and the gas was either pure or mixed with argon or nitrogen. Comparison is made between the experimental results and computations taking into account the off-diagonal elements of the relaxation matrix.
