High resolution study of the ν1+2ν2−ν2 and 2ν2+ν3−ν2 “hot” bands and ro-vibrational re-analysis of the ν1+ν2/ν2+ν3/3ν2 polyad of the 32SO2 molecule

The weak “hot” absorption bands, ν1+2ν2−ν2 and 2ν2+ν3−ν2, were analysed with high resolution using the Fourier transform interferometer Bruker IFS-120 HR. In order to make possible an analysis of the ν1+2ν2−ν2 and 2ν2+ν3−ν2 bands, as the first step, we re-analysed considerably the stronger “cold” bands, ν1+ν2 and ν2+ν3, which are located in the same spectral regions. As the result of analysis we obtained about 2650 and 2050 transitions (1069 and 1001 upper state ro-vibrational energy values) with Jmax. = 78, Kamax. = 27 and Jmax. = 68, Kamax. = 24 for the bands ν1+ν2 and ν2+ν3, respectively, that is considerably higher than in the earlier studies of corresponding bands (Jmax. = 33, Kamax. = 7 and Jmax. = 50, Kamax. = 16 for the same bands, ν1+ν2 and ν2+ν3, respectively). A strong local resonance interaction with the 3ν2 band was taken into account, and the set of parameters that reproduce the initial experimental data with an accuracy close to experimental uncertainties, was obtained. The weak ν1+2ν2−ν2 and 2ν2+ν3−ν2 bands were assigned, and about 870 and 930 transitions (553 and 540 upper state ro-vibrational energy values) with Jmax. = 60 and Kamax. = 20 and Jmax. = 59 and Kamax. = 16 were assigned to the ν1+2ν2−ν2 and 2ν2+ν3−ν2 bands, respectively. A complete list of assigned transitions is presented, and corresponding spectroscopic parameters are obtained from the fit of assigned transitions (upper energy values).

Research Highlights► SO2 high-resolution spectrum are recorded in the region 1500-2300 cm−1. ► More than 6500 transitions are assigned to the ν1+ν2, ν2+ν3, and 3ν2 bands. ► Experimental spectrum is filtered from lines of the ν1+ν2, ν2+ν3, and 3ν2 bands. ► 1090 transitions are assigned to the “hot” bands ν1+2ν2−ν2 and 2ν2+ν3−ν2. ► Spectroscopic parameters of all discussed bands are determined.