New acetylene line list near 3.8-μm – Part II

Abstract

The investigation of the 3.8 µm spectral region of acetylene 12C2H2 main isotopologue has been completed from spectra recorded with Fourier Transform Spectrometer (FTS) using high optical path length. This work is the second of a series dedicated to the ΔP = 4 spectral region. In the first paper of the series (JQSRT 2023;295:108413) 14 bands of 12C2H2 were studied in the beginning of the region. In the present work the whole ΔP = 4 spectral region was investigated. 52 newly observed vibrational bands have been studied as well as the 5 intense bands present in the HITRAN and GEISA databases. The band centers and the upper level spectroscopic constants were retrieved for all bands. The comparison with the data from HITRAN and GEISA databases revealed important deviations from the measurements due to wrong extrapolations (especially line positions). The effective dipole moment operator parameters describing intensities of all transitions observed in the ΔP = 4 spectra region were refined. A complete list of calculated line parameters for 7515 transitions has been generated for 71 bands between 2389 cm−1 and 2890 cm−1.