Measurement of positions, intensities and self-broadening line shape parameters of H2O lines in the spectral ranges 1850–2280 cm−1 and 2390–4000 cm−1

Abstract

A Bruker IFS 125 HR Fourier transform spectrometer was used to measure several pure water transmittance spectra in the spectral range 1850–4000cm−1. A total of 15 measurements with absorption path lengths between 24.9cm and 174.6m and sample gas pressures from 0.1 to 20mbar were performed at 296K. The transmittance spectra were corrected for various error sources and were analyzed in the spectral ranges 1850–2280cm−1 and 2390–4000cm−1 for the majority of intensities between 3×10–26 and 3×10–19cm molecule−1. A multispectrum fitting approach was used applying a quadratic speed-dependent Voigt model extended to account for line mixing in the Rosenkranz first order perturbation approximation. Line positions, intensities, self-broadening widths, their speed-dependence and in some cases line mixing had to be adjusted for fitting the measurements to noise level. An extensive error estimation calculation was performed propagating several instrumental and measurement errors into individual parameter inaccuracies. The determined parameters are compared to HITRAN12 and independent experimental values while intensities are compared to recent ab initio calculations performed at UCL. The overall agreement between ab initio calculations and experimental values is remarkable and below 1% in most cases. The determined line parameters are provided as a supplement to this publication.