First rotational analysis of the (111) and (021) vibrational state of S16O18O from the “hot” ν1+ν2+ν3−ν2 and 2ν2+ν3−ν2 bands

•32S16O18O molecule.•“Hot” bands.•Determination of parameters.

The rotational structure of the (111) and (021) vibrational states is determined for the first time from the high resolution analysis of the ν1+ν2+ν3−ν2 and 2ν2+ν3−ν2 “hot” bands. The 480 and 74 transitions of these bands (Jmax/Kamax = 45/14 and 15/12 respectively) were assigned in the spectra, which have been recorded with the Bruker IFS 120 Fourier transform infrared (FTIR) spectrometer. A weighted fit analysis allowed us to generate a set of 5 fitted parameters for the (111) state and 4 fitted parameters for the (021) state. Calculation with the 9 parameters, obtained from the fit, reproduces the initial 363 energy values (about 550 assigned experimental transitions) of two vibrational states with the drms deviations of 3.2×10−4 cm−1, which is comparable with the experimental uncertainties of very weak transitions of the ν1+ν2+ν3−ν2 and 2ν2+ν3−ν2 “hot” bands in our experiment.