Measurements and calculations of air-broadening and shift parameters of water vapour transitions in a wide spectral region. (19th May 2021) - Petrova, T. M.
Abstract : The water vapour line broadening ( γ ) and shifting ( δ ) coefficients for 212 lines of eight vibrational bands, namely, ν 2 + ν 3, 2 ν 2 + ν 3, 3 ν 2 + ν 3 – ν 2, 4 ν 2, ν 1 + ν 3, ν 1 + ν 2, ν 1 + 2 ν 2 and 2 ν 1, in the 5800–6700 cm –1 spectral region induced by air are measured using Fourier transform infrared spectroscopy. The measurements are performed with a spectral resolution of 0.01 cm –1 and in a wide pressure range of air. The calculations of δ are based on the Anderson–Tsao–Curnutte theory. The measured γ values are combined with literature data for the half-widths found for the lines in the 380–14, 000 cm –1 spectral region. The combined experimental data for N = 1386 measured γ coefficients of 17 vibrational bands of the H2 O molecule perturbed by air are fitted to an empirical function. Two fitting procedures are used, with one considering the fit of the measured γ for individual rotational branches and the other considering the global fit of all 1386 measured γ . The computed γ values derived from the fitted parameters are compared statistically to the measurements. The vibrational dependence of the measured γ and their compatibility are discussed. The obtained fitted parameters of the empirical function are used for the analysis of γ for the lines in the 13, 000 to 26, 000 cm –1 spectral region. GRAPHICAL ABSTRACT: