Rotational Structure in the Absorption Spectrum of SO2 between 3000 Å and 3300 Å

Abstract

Rotational analyses have been carried out, with varying degrees of completeness, for nine bands of S16O2 and two bands of S18O2 in the region 3000–3300 Å. The bands are all highly perturbed type C bands, which go to b2 vibrational levels of the ππ* Ã1A2 electronic state. The [Formula: see text] electronic transition shows an anomalous vibrational intensity distribution, which indicates that the Ã1A2 state undergoes strong Born–Oppenheimer (nuclear momentum) vibronic coupling with the [Formula: see text] electronic state. All the obvious banded structure in this wavelength region can be assigned to the [Formula: see text] transition. Although no analyses of bands belonging to the [Formula: see text] transition have been carried out (since the [Formula: see text] state is so massively perturbed by the ground state), reasons are presented for placing its (0,0) band between 3100 and 3160 Å.