Measurements and calculations of Xe-broadening and shift parameters of water vapour transitions in a wide spectral region

Abstract

The water vapour line broadening (γ) and shifting (δ) coefficients for 687 lines of 14 vibrational bands ν1, ν3, 2ν2, ν1 + ν2, ν2 + ν3, 3ν2, 2ν2 + ν3, ν1 + 2ν2, ν1 + ν3, 2ν1, 2ν3, 4ν2, 6ν2, and 3ν2 + ν3 induced by xenon pressure were measured with Bruker IFS 125 FTIR spectrometer. The measurements were performed at room temperature, at the spectral resolution of 0.01 cm−1 and in a wide pressure range of Xe. The broadening and shift coefficients were calculated using a semi-classical method. The intermolecular potential was taken as the sum of the anisotropic atom–atom potential and vibrationally and rotationally dependent isotropic Lennard-Jones potential. The optimal sets of potential parameters that gave the best agreements with measured coefficients γ and δ for each vibrational band were found. The measured coefficients γ were combined with the data found earlier for the ν1 + ν2 + ν3 bands as well as with those reported in literature for the ν2, ν1, ν3, 2ν1 + 2ν3, 2ν1 + 2ν2 + ν3 and 3ν1 + ν3 bands and N = 820 coefficients γ of19 vibrational bands of H2O perturbed by Xe were fitted to the empirical functions. The computed coefficients γ and δ derived from the semi-classical method as well as from the fitted parameters were compared statistically to measurements.