Measurements of air-broadening parameters of water vapour transitions in the 7520–8586 cm−1 spectral region

Abstract

The water vapour line broadening (γ) and shift (δ) coefficients for 319 lines of 11 vibrational bands 2ν₃, 2ν₂ +ν₃, 3ν₂+ν₃, 5ν₂, 6ν₂, ν₁+ν₃, ν₁+ν₂+ν₃, ν₁+2ν₂, ν₁+3ν₂, 2ν₁, and 2ν₁+ν₂ from the spectral region 7520–8586 cm^–1 induced by air pressure were measured with a Bruker IFS 125 spectrometer. The measurements were performed at a spectral resolution of 0.01 cm^–1 and over a wide air pressure range. The calculations of the line-shift coefficients δ were performed in the framework of a semi-classical method. The measured air-broadening coefficients γ were combined with literature data for air- and N₂-broadening coefficients γ measured for the lines in the 380–22,593 cm^–1 spectral region. Combined experimental data for N = 4110 measured coefficients γ of 76 vibrational bands of H₂O molecules were fitted to the empirical functions. The computed coefficients γ derived from the fitted parameters were statistically compared with the measurements. The vibrational dependence of the measured γ values and their compatibility is discussed. GRAPHICAL ABSTRACT