Narrowing and broadening parameters for H2O lines perturbed by helium, argon and xenon in the 1170–1440 cm−1 spectral range

Collision effects on water vapor at low concentration in a mixture with noble gases (helium, argon and xenon) have been studied by Fourier transform spectroscopy in the pressure range where line narrowing by dynamic confinement (Dicke effect) and collision broadening are observable, i.e. when the Voigt function cannot reproduce the observed profiles. Precise values of the broadening parameter have been obtained for the P and Q branches of the H2O ν 2 band taking into account molecular confinement (hard or soft collisions). The broadening parameter value derived from a Voigt profile for H2O lines perturbed by helium is smaller by about 10% than values determined using the soft or hard collision model. For H2O lines perturbed by argon or xenon this difference can reach more than 50% for the narrowest lines.