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Updated: Jul 2, 2026

Inactivation of Pathogens via Visible-Light Photolysis of Riboflavin-5′-Phosphate
Published on: April 6, 2022
Photophysics and deactivation pathways of thymine
Gunther Zechmann1, Mario Barbatti
1Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, UK. gunther.zechmann@chem.ox.ac.uk
Abstract:
Combined complete active space perturbation theory (CASPT2) and multireference configuration interaction calculations with single and double excitations (MR-CISD) were performed in order to explore possible deactivation pathways of thymine after photoexcitation. Equilibrium geometries are reported together with a total of eight extremes (minima or maxima) on the crossing seam (MXS), through which such radiationless transitions may occur. Furthermore, conformational analysis allows grouping these conical intersections in five distinct types. Reaction paths were calculated connecting the S1 (1)n pi* minimum with the lowest-energy MXS of each group. Two distinct types of paths were observed, both with features that should delay the internal conversion to the ground state. This is shown to provide a possible explanation for the relatively long excited-state lifetime of thymine.
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