High resolution analysis of 32 S18O2 spectra: The ν1 and ν3 interacting bands

Highly accurate, image, ro-vibrational spectrum of S18O2 was recorded with Bruker IFS 120 HR Fourier transform interferometer in the region of 1050–1400 cm−1 where the bands ν1 and ν3 are located. About 1560 and 1840 transitions were assigned in the experimental spectrum with the maximum values of quantum numbers image equal to 65/22 and 58/16 to the bands ν3 and ν1, respectively. The further weighted fit of experimentally assigned transitions was made with the Hamiltonian model which takes into account Coriolis resonance interaction between the vibrational states (100) and (001). To make the ro-vibrational analysis physically more suitable, the initial values of main spectroscopic parameters have been estimated from the values of corresponding parameters of the S16O2 species on the basis of the results of the Isotopic Substitution theory. Finally, the set of 23 spectroscopic parameters obtained from the fit reproduces values of 1292 initial “experimental” ro-vibrational energy levels (about 3400 transitions assigned in the experimental spectrum) with the image. Also, the ground state parameters of the S18O2 molecule were improved