Nature of the temperature dependence of the absorption coefficient in the remote wing of the 4.3 μm CO2 band

The complex nature of the temperature dependence of the absorption coefficient beyond the edge of the CO2 4.3 μm band — the change of the sign of the derivative of the absorption coefficient with respect to the temperature near the edge and in the remote wing of the band — is explained on the basis of the theory of spectrum line wings. The first change in the sign is due to the temperature dependence of the classical potential of intermolecular interaction; the second depends mainly on the difference in the quantum energies of molecule interaction. Therefore, a study of the dependence of the absorption coefficient on the temperature in the band wings provides information about the nature of the terms of the interacting molecules.