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

• Published in: Molecular physics Vol. 119; no. 10; p. e1906967
• Main Authors: Petrova, T. M., Solodov, A. M., Solodov, A. A., Deichuli, V. M., Starikov, V. I.
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis 19.05.2021; Taylor & Francis Ltd
• Subjects: analysis; Empirical analysis; Fourier transforms; Line broadening; Mathematical analysis; measured width; Parameters; Spectra; Spectral resolution; Water chemistry; Water vapor
• ISSN: 0026-8976; 1362-3028
• DOI: 10.1080/00268976.2021.1906967

The water vapour line broadening (γ) and shifting (δ) coefficients for 212 lines of eight vibrational bands, namely, ν 2  + ν 3 , 2ν 2  + ν 3 , 3ν 2  + ν 3 -ν 2 , 4ν 2 , ν 1  + ν 3 , ν 1  + ν 2 , ν 1  + 2ν 2 and 2ν 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 H 2 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.