LINESHAPES AND BROADENING COEFFICIENTS IN THE NU-5 BAND OF C2H2 IN COLLISION WITH KR AND HE

General Voigt profiles (GVPs), including the speed dependence of collisional cross-sections, have been fitted to the following measured spectral lineshapes: the shapes of the R(7), R(11) and R(14) lines recorded with a tunable diode-laser spectrometer in the v5 band of C2H2 in collision with He and Kr. The various GVPs and the resulting broadening coefficients are almost identical for light perturbers such as He and depend significantly on a simplified form in r(-q) of the interaction potential for heavy perturbers such as Kr. We consider three GVPs with q = 3 (Voigt function), q = 6 and q = 12, as well as the Galatry profile incorporating Dicke narrowing associated with velocity-changing collisions. The speed-dependent Voigt profile with q = 6 provides generally closer agreement with the spectral data of C2H2-Kr than the other GVPs and leads to Kr-broadening coefficients that are nearly 5% larger than those derived from the conventional Voigt profile.