Broadening, shifting, and line asymmetries in the 2←0 band of CO and CO–N2: Experimental results and theoretical calculations

We have measured the room temperature, widths, pressure shifts, and line asymmetry coefficients for many transitions of the first overtone band of CO and CO perturbed by ${\mathrm{N}}_2.$ The broadening coefficients were obtained with an accuracy of about 1%. The pure CO profiles have been fitted by a Voigt profile while the ${\mathrm{CO–N}}_2$ spectral profiles have been fitted with a Lorentz and an empirical line shape model $({\mathrm{HC}}_v)$ that blends together a hard collision model and a speed-dependent Lorentz profile. In addition to the Voigt, Lorentz, and ${\mathrm{HC}}_v$ models, we have added a dispersion profile to account for weak line mixing. The line broadening and shift coefficients are compared to semiclassical calculations employing a variety of intermolecular interactions. The line asymmetry results are compared to line mixing calculations based on the energy corrected sudden (ECS) model. The results indicate that effects other than line mixing also contribute to the measured line asymmetry.