title: Excited-state relaxation of hydrated thymine and thymidine measured by liquid-jet photoelectron spectroscopy: experiment and simulation.
abstract: Time-resolved photoelectron spectroscopy is performed on thymine and thymidine in aqueous solution to study the excited-state relaxation dynamics of these molecules. We find two contributions with sub-ps lifetimes in line with recent excited-state QM/MM molecular dynamics simulations (J. Chem. Phys. 2013, 139, 214304). The temporal evolution of ionization energies for the excited ππ* state along the QM/MM molecular dynamics trajectories were calculated and are compatible with experimental results, where the two contributions correspond to the relaxation paths in the ππ* state involving different conical intersections with the ground state. Theoretical calculations also show that ionization from the nπ* state is possible at the given photon energies, but we have not found any experimental indication for signal from the nπ* state. In contrast to currently accepted relaxation mechanisms, we suggest that the nπ* state is not involved in the relaxation process of thymine in aqueous solution.
authors: Max-Born-Institut für nichtlineare Optik und Kurzzeitspektroskopie , Max-Born-Straße 2A, 12489 Berlin, Germany.
authors: Franziska
authors: F
authors: Buchner
authors: Akira
authors: A
authors: Nakayama
authors: Shohei
authors: S
authors: Yamazaki
authors: Hans-Hermann
authors: HH
authors: Ritze
authors: Andrea
authors: A
authors: Lübcke
mesh_terms: D006859:Hydrogen / Q000737:chemistry; D008968:Molecular Conformation; D056004:Molecular Dynamics Simulation; D056951:Photoelectron Spectroscopy; D013936:Thymidine / Q000737:chemistry*; D013941:Thymine / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water; D006859:Hydrogen; D013941:Thymine; D013936:Thymidine