Inhomogeneous lineshape profiles of C2H2 perturbed by Xe

Several infrared transitions of the v(s), band of C2H2 perturbed by Xe near 700 cm(-1) have been recorded using a tunable diode-laser spectrometer, eq uipped with a thermostatically regulated cell. The pressure and temperature regimes covered during the experiments are respectively ranging between 7, 20 and 200 mbar and 170 and 350 K. The experimental profiles are accurately studied with a recently proposed lineshape model accounting for the collis ional confinement narrowing of the Doppler spectral contribution, the inhom ogeneous collisional broadening and shifting, and the exchange between the various speed classes of the Maxwell-Boltzmann distribution. The speed depe ndence of the collisional broadening is either ab initio calculated from a semiempirical potential or deduced from the experimental temperature depend ence of the line broadening. It is shown that, for the considered range of temperature, this speed dependence does not significantly modify the linesh ape, so that the usual hard and soft models conveniently account for most o f the observed effects. (C) 1999 Academic Press.