Experimental and theoretical CO₂–Ar pressure-broadening cross sections and their temperature dependence

Line broadening coefficients of the CO₂–Ar fundamental ν₃ band are obtained experimentally and theoretically for temperatures from 120 to 765 K. The experimental results are obtained by Fourier-transform infrared spectroscopy. Theoretical values are provided ia quantum-mechanical (close coupling and coupled states) approaches as well as semiclassical (improved Smith–Giraud–Cooper and Robert–Bonamy) methods. The most up-to-date CO₂–Ar ab initio intermolecular potential (J. M. Hutson, A. Ernesti, M. M. Law, C. F. Roche and R. J. Wheatley, J. Chem. Phys., 1996, 105, 9130) is employed for all calculations. For all the temperatures probed, theoretical values are found to be in a rather good agreement with experiment. In addition, the Raman Q(j) line broadening coefficients and the application of the random phase approximation are presented.