Pressure broadening of CO and OCS spectral lines

We review briefly the principal features of two semi-classical impact theories of collisional line-broadening, Anderson-Tsao-Curnutte theory and the more recent theory of Robert and Bonamy. These models are applied to the calculation of self-, N-, O- and CO- broadened linewidths of CO and of self-, O-, and N- broadened linewidths of OCS. In addition to the electrostatic interactions, we consider two anisotropic potentials, a simple one governing dispersion interaction and a more elaborate atom-atom interaction potential. Selected experimental values for broadening coefficients of CO and OCS at room temperature and around 200 K are compared with the theoretical values. Conclusions on the two theories and the intermolecular potentials used are drawn from this comparison.