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

Abstract

ABSTRACTThe water vapour line-broadening (γ) and shift (δ) coefficients for 310 lines of 10 vibrational bands ν1, ν3, 2ν2, ν1+ ν2, ν2+ ν3, 2ν2 +ν3, 2ν1, ν1+ ν3, 2ν3 and ν1 +2ν2 induced by argon pressure were measured with a Bruker IFS HR 125 spectrometer. The measurements were performed at room temperature, at the spectral resolution of 0.01 cm–1 and over a wide pressure range of Ar. The calculations of the broadening coefficients γ and δ were performed in the framework of the semi-classical method. The intermolecular potential was taken as the sum of the atom–atom potential and the vibrationally and rotationally dependent isotropic induction+dispersion potential. The measured γ and δ were combined with literature data for the ν2 and 3ν1+ν3, 2ν1+2ν2+ν3 vibrational bands, and the optimal sets of potential parameters that gave the best agreement with the measured broadening coefficients for each vibrational band separately were found. Then, combined experimental data of 13 vibrational bands of H2O perturbed by Ar were used to determine the analytical dependence of some potential parameters on vibrational quantum numbers.