Line parameters of acetylene in the 1.9 and 1.7 μm spectral regions

Abstract

Using FT spectra (Bruker IFS 120, unapodized resolution≈0.01 cm −1) of acetylene 12C 2H 2, line positions and intensities, as well as self-broadening and -shifting coefficients are measured for about 550 lines of 13 bands between 5000 and 6000 cm −1. A multispectrum fitting procedure is used to retrieve line parameters from four experimental spectra recorded at different pressures. An absolute wavenumber calibration has been performed using isolated acetylene line positions around 5900 cm −1. The average accuracy of the line parameters obtained in this work is estimated to be ±0.001 cm −1 for line positions, 5–10% for line intensities depending on the transitions, about 5% for self-broadening coefficients, and ±0.005 cm −1 atm −1 for self-shifting coefficients. For each studied band, the vibrational transition dipole moment squared and the empirical Herman–Wallis coefficients are adjusted. The measured line intensities allow to obtain the effective dipole moment parameters of the global approach for the Δ P=8 and 9 series. A polynomial description of the rotational dependence of self-broadening coefficients is performed. A weak rotational dependence of the self-shifting coefficients is observed.