Line shapes in the far wings of allowed transitions

A far‐wing line shape theory based on the binary collision and quasistatic approximations that is applicable for both the low‐ and high‐frequency wings of the vibration‐rotational bands has been developed. This theory has been applied in order to calculate the frequency and temperature dependence of the continuous absorption coefficient for frequencies up to 10 000 cm−1 for pure H2O, and for H2O‐N2 and H2O‐CO2 mixtures. The calculations were made assuming an interaction potential consisting of an isotropic Lennard‐Jones part with parameters that are consistent with values obtained from other data, and the leading long‐range anisotropic part, together with the measured line strengths and transition frequencies. Current work in progress to extend the theory to multi‐component anisotropic potentials, to account for the effects of molecular motion on the near wings, and to validate the theory with recent experimental data will be discussed briefly.