Photoabsorption Assignments for the C̃1B2 ← X̃1A1 Vibronic Transitions of SO2, Using New Ab Initio Potential Energy and Transition Dipole Surfaces

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• 作者：Praveen KumarBin Jiang ; Hua GuoJacek Kłos ; Millard H. AlexanderBill Poirier
• 刊名：Journal of Physical Chemistry A
• 出版年：2017
• 出版时间：February 9, 2017
• 年：2017
• 卷：121
• 期：5
• 页码：1012-1021
• 全文大小：502K
• ISSN：1520-5215

文摘

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 C̃¹B₂ ← X̃¹A₁ 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 C̃¹B₂ 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 C̃¹B₂ state, we compute vibrational energy levels and wave functions, and compare with a photoabsorption calculation obtained using the same PES and corresponding C̃¹B₂ ← X̃¹A₁ 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.