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Updated: Aug 5, 2026

Molecular Beam Mass Spectrometry With Tunable Vacuum Ultraviolet (VUV) Synchrotron Radiation
Published on: October 30, 2012
Time-Resolved Photoelectron Spectroscopy of 1,3-Dimethyluracil and 1,3-Dimethylthymine
Wenping Wu1,2, Yuhuan Tian1,2, Baihui Feng1,3
1State Key Laboratory of Chemical Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian, Liaoning116023, China.
Abstract:
The ultraviolet-induced electronic relaxation dynamics of 1,3-dimethyluracil and 1,3-dimethylthymine are investigated using the femtosecond time-resolved photoelectron spectroscopy (fs-TRPES) method. In both cases, an ultrashort time constant of sub-100 fs is observed and assigned to the lifetime of the initially (optically) prepared S2(1ππ*) state, while the dark S1(1nπ*) state is subsequently populated, followed by a final decay within several picoseconds. In addition, the effects of 5-position methylation on the excited-state dynamics can be explored and discussed by comparing the measured TRPES spectra of 1,3-dimethyluracil and 1,3-dimethylthymine. We tentatively propose that the quantum yield of the S1(1nπ*) state is different in the cases of 1,3-dimethyluracil and 1,3-dimethylthymine, while the latter is suggested to have a higher 1nπ* yield than the former, based on the decay-associated spectra derived from the analysis of the TRPES spectra.
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