Excited-state relaxation of hydrated thymine and thymidine measured by liquid-jet photoelectron spectroscopy: experiment and simulation

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.

Keywords

Ground state, Ionization, Liquids, Molecular dynamics, Photoelectron spectroscopy, Photoelectrons, Photoionization, Photons, Relaxation processes, Solutions, Conical intersection, Excited state relaxation, Molecular dynamics simulations, Molecular dynamics trajectories, Relaxation mechanism, Temporal evolution, Theoretical calculations, Time-resolved photoelectron spectroscopy, Excited states, thymidine, thymine, hydrogen, thymidine, thymine, water, ab initio calculation, aqueous solution, Article, controlled study, electron, excitation, hydration, ionization, liquid, molecular dynamics, molecular mechanics, photon, quantum mechanics, simulation, static electricity, theoretical model, time, X ray photoelectron spectroscopy, chemistry, conformation, Hydrogen, Molecular Conformation, Molecular Dynamics Simulation, Photoelectron Spectroscopy, Thymidine, Thymine, Water

URI

https://oa.tib.eu/renate/handle/123456789/9457
https://doi.org/10.34657/8495

Citation

Buchner, F., Nakayama, A., Yamazaki, S., Ritze, H.-H., & Lübcke, A. (2015). Excited-state relaxation of hydrated thymine and thymidine measured by liquid-jet photoelectron spectroscopy: experiment and simulation. 137(8). https://doi.org//10.1021/ja511108u

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Chemie

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CC BY 4.0 Unported

https://creativecommons.org/licenses/by/4.0/

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