Algebraic Methods for the Quantitative Interpretation of Vibronically-Resolved Molecular Spectra:. the Structure and Dynamics of Disulfur Monoxide (S2O)

A coupled U(2) algebraic theory has been employed to perform detailed analyses on absorption and emission spectra recorded for the C∼¹ A' - X∼¹ A' (π* ← π) electronic system of jet-cooled disulfur monoxide (S₂O) molecules. Vibronically-resolved features possessing up to 20 quanta of excitation in the ν₂ S-S stretching mode of the X∼ state (E_vib <14000cm^-1) and up to 8 quanta of excitation in the analogous ν'₂ vibration of the C∼ state (E_vib < 3500cm^-1) have been examined. Aside from providing an economical description for the inherently anharmonic and strongly coupled patterns of energy levels that distinguish highly-excited polyatomic species, the algebraic approach enables facile evaluation of multidimensional Franck-Condon factors required for the interpretation of spectral intensities. This ability to extract wavefunction information directly from spectroscopic data sets has revealed pronounced differences in the vibrational dynamics supported by the C∼¹A' and X∼¹A' manifolds, with the latter found to be substantially more "local" in character than the former.