Temperature, pressure, and perturber dependencies of line-mixing effects in CO2 infrared spectra. II. Rotational angular momentum relaxation and spectral shift in Σ←Σ bands

Abstract
The Energy Corrected Sudden approach is used in order to deduce collisional parameters and to model infrared quantities in Σ-Σ bands of CO 2 -He and CO 2 -Ar mixtures at room temperature. Measurements are first used for the determination (from a fit) of the rotational angular momentumrelaxation time and of some parameters representative of the imaginary part of the relaxation operator. It is shown that line-broadening data as well as absorption in both the wing and central part of the ν 3 and 3ν 3 bands lead to consistent determinations. The model is then used for detailed analysis of line-mixing effects. The influences of pressure, of the band spectral structure, and of the collision partner are studied. Differences between the effects of collisions with He and Ar are pointed out and explained.

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