Measurements and calculations of xenon broadening and shift parameters of water vapour transitions for ν1 + ν2 + ν3 band

Abstract

The water vapour line broadening and shifting of 72 lines in the ν1 + ν2 + ν3 vibrational band of H2O (in the 8603–8997 cm−1 spectral region) induced by xenon pressure were measured with a Bruker IFS HR FTIR spectrometer. These measurements were performed at room temperature, at a spectral resolution of 0.01 cm−1 and over a wide range of Xe pressure. The broadening and shift coefficients were also calculated using a semi-classical method. The intermolecular potential was taken as the sum of the anisotropic atom–atom potential and the effective vibrationally and rotationally dependent isotropic Lennard–Jones potential.The measured coefficients γ and δ were combined with data from the literature on the ν2, ν1, ν3, 2ν1 + 2ν3, 2ν1 + 2ν2 + ν3, and 3ν1 + ν3 bands, and optimal sets of potential parameters were found that gave the best agreement with the measured broadening coefficients. A strong influence of the imaginary part of the scattering matrix on the calculated values of the γ and δ coefficients was observed. The results were compared with those for He-, Ar-, and Kr-broadenings. The measured broadening coefficients were fitted to empirical expressions. The calculated values of the γ and δ coefficients were compared statistically to the measured values.