High resolution FTIR spectroscopy of sulfur dioxide in the 1550-1950 cm−1 region: First analysis of the ν1+ν2/ν2+ν3 bands of 32S16O18O and experimental line intensities of ro-vibrational transitions in the ν1+ν2/ν2+ν3 bands of 32S16O2, 34S16O2,

The high resolution infrared spectra of the 32S16O18O molecule were recorded for the first time with a Bruker IFS 120 HR Fourier transform interferometer and analysed in the region of 1550-1950 cm−1 where the bands ν1+ν2 and ν2+ν3 are located. About 1050 and 1570 transitions were assigned in the experimental spectra with the maximum values of quantum numbers Jmax./Kamax. equal to 64/16 and 58/19 to the bands ν1+ν2 and ν2+ν3, respectively. The subsequent weighted fit of experimentally assigned transitions was made with the Hamiltonian model which takes into account the resonance interactions between the studied vibrational states. As the result, a set of 16 fitted parameters was obtained which reproduces the initial 1442 ro-vibrational energy values obtained from the assigned transitions with the drms=3.7×10−4cm−1. An analysis of more than 4050 experimental ro-vibrational line intensities of the ν1+ν2 and ν2+ν3 bands of 32S16O2 was made, and a set of 7 effective dipole moment parameters was obtained which reproduce the initial experimental line intensities with the drms=6.9%. Values of these parameters, being re-calculated to the values of corresponding parameters of the 34S16O2, 32S18O2 and 32S16O18O species were used for calculation of line intensities in the ν1+ν2 and ν2+ν3 bands of these three isotopologues. A list of transitions with their line intensities in the region of 1550-1950 cm−1 for the four mentioned species is generated.