High resolution analysis of the SO2 spectrum in the 2600-2900cm−1 region: 2ν3, ν2+2ν3−ν2 and 2ν1+ν2 bands

Infrared spectrum of the SO2 molecule was recorded with high resolution in the 2600-2900cm−1 region. Spectrum was recorded with the Fourier transform interferometer Bruker IFS-120 HR in Oulu (Finland) with the pressure of 111 Pa and the absorption path length of 163.2 m that allowed us to record 2ν3 and 2ν1+ν2 weak bands. The 2ν3 band discussed earlier by Lafferty et al., was re-analyzed, and considerably more information was extracted from the spectrum (more than 3800 transitions of the 2ν3 band were assigned in the experimental spectrum with maximum values of quantum numbers, Jmax.=76 and Kamax.=26). On the basis of the procedure discussed in Ulenikov et al., about 760 transitions of the ν2+2ν3−ν2 hot band (Jmax.=49 and Kamax.=13), were assigned, and the rotational structure of the (012) vibrational state was determined for the first time with high accuracy. Very weak band, 2ν1+ν2, was analyzed also for the first time, and about 1250 transitions with Jmax.=43 and Kamax.=17 were assigned in the spectrum. Information, obtained from the experimental data, was used in the fit for the determination of spectroscopic parameters of the states (002), (012), and (210). In this case, some earlier undiscussed sets of interacting ro-vibrational states were found, and resonance interactions between the states (002)/(130) and (012)/(140) were taken into account. Obtained from the fit, 36 parameters reproduce more than 5800 initial transitions of all three bands with the accuracy close to experimental uncertainties (rms deviation is 0.00021cm−1, 0.00031cm−1 and 0.00014cm−1 for the 2ν3, ν2+2ν3−ν2 and 2ν1+ν2 bands, respectively).

► The first high resolution analysis of the very weak bands, ν2+2ν3−ν2 and 2ν1+ν2. ► Increasing more than three times information about the 2ν3 band than was known before. ► Determination and improvement of spectroscopic parameters of studied bands.