Decay Pathways of Thymine Revisited

  J. Phys. Chem. A, 2018, 122 (21),  4819–4828


The decay of electronically excited states of thymine (Thy) and thymidine 5′-monophosphate (TMP) was studied by time-resolved UV/vis and IR spectroscopy. In addition to the well-established ultrafast internal conversion to the ground state, a so far unidentified UV-induced species is observed. In D2O, this species decays with a time constant of 300 ps for thymine and of 1 ns for TMP. The species coexists with the lowest triplet state and is formed with a comparably high quantum yield of about 10% independent of the solvent. The experimentally determined spectral signatures are discussed in the light of quantum chemical calculations of the singlet and triplet excited states of thymine.

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