Photoabsorption Assignments for the C1B2 ← X1A1 Vibronic Transitions of SO2, Using New Ab Initio Potential Energy and Transition Dipole Surfaces

Praveen Kumar, Bin Jiang, Hua Guo, Jacek Kłos, Millard H. Alexander, Bill Poirier

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12 Scopus citations


The high resolution spectroscopy of the SO2 molecule is of great topical interest, in a wide variety of contexts ranging from origins of higher life, to astrophysics of the interstellar medium, to environmental chemistry. In particular, the C1B2 ← X1A1 UV photoabsorption spectrum has received considerable attention. This spectrum exhibits a highly regular progression of ∼20 or so strong peaks, spaced roughly 350 cm-1 apart, which is comparable to the C1B2 bending vibrational frequency. Accordingly, they have for decades been largely attributed to the (1, v2′, 2) ← (0, 0, 0) bend progression. Using a highly accurate new ab initio potential energy surface (PES) for the C1B2 state, we compute vibrational energy levels and wave functions, and compare with a photoabsorption calculation obtained using the same PES and corresponding C1B2 ← X1A1 transition dipole surface (TDS). We find that the above putative assignment is incorrect, contradicting even general qualitative trends - thus necessitating a very different dynamical picture for this highly unusual molecule.

Original languageEnglish
Pages (from-to)1012-1021
Number of pages10
JournalJournal of Physical Chemistry A
Issue number5
StatePublished - Feb 9 2017


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