Pressure-induced line mixing in the ν4 band of NH3 perturbed by O2 and self-perturbed

In order to predict these line-mixing parameters, we have calculated state-to-state cross sections for NH3 perturbed by O2- and self-perturbed using a semiclassical model. The predicted values are in reasonable agreement with the measurements for O2- and self-broadening. This calculation illustrates that the state-to-state cross section contributions to the line-mixing parameters mainly arises from the energy transfer between symmetric and asymmetric components of the inversion doublets. An examination of these cross sections shows a pronounced J and K quantum number dependence.