%0 Journal Article
%A Faccialà, Davide
%A Bonanomi, Matteo
%A Tenorio, Bruno Nunes Cabral
%A Avaldi, Lorenzo
%A Bolognesi, Paola
%A Callegari, Carlo
%A Coreno, Marcello
%A Coriani, Sonia
%A Decleva, Piero
%A Devetta, Michele
%A Došlić, Nađa
%A De Fanis, Alberto
%A Di Fraia, Michele
%A Lever, Fabiano
%A Mazza, Tommaso
%A Meyer, Michael
%A Mullins, Terry
%A Ovcharenko, Yevheniy
%A Pal, Nitish
%A Piancastelli, Maria Novella
%A Richter, Robert
%A Rivas, Daniel E.
%A Sapunar, Marin
%A Senfftleben, Björn
%A Usenko, Sergey
%A Vozzi, Caterina
%A Gühr, Markus
%A Prince, Kevin
%A Plekan, Oksana
%T Unraveling the Relaxation Dynamics of Uracil: Insights from Time-Resolved X-ray Photoelectron Spectroscopy
%J Journal of the American Chemical Society
%V 147
%N 34
%@ 0002-7863
%C Washington, DC
%I ACS Publications
%M PUBDB-2025-04604
%P 30694 - 30707
%D 2025
%Z cc-by
%X We report a study of the electronic and nuclear relaxation dynamics of the photoexcited RNA base uracil in the gas phase using time-resolved core-level photoelectron spectroscopy together with high-level calculations. The dynamics was investigated by trajectory surface hopping calculations, and the core ionization energies were calculated for geometries sampled from these. The molecule was excited by a UV laser and dynamics probed on the oxygen, nitrogen, and carbon sites by core electron spectroscopy. We find that the main de-excitation channel of the initially excited S2(ππ*) state involves internal conversion to the S1(nπ*) state with a time constant of 17 ± 4 fs, while a portion of S2(ππ*) population returns directly to the ground state by internal conversion. We find no evidence that the S1(nπ*) state decays to the ground state; instead, it decays to triplet states with a time constant of 1.6 ± 0.4 ps. Oscillations of the S1(nπ*) state O 1s intensity as a function of time correlate with those of calculated C4═O8 and C5═C6 bond lengths, which undergo a sudden expansion following the initial π → π* excitation. Our calculations support our interpretation of the data and provide detailed insight into the relaxation processes of uracil.
%F PUB:(DE-HGF)16
%9 Journal Article
%$ pmid:40802197
%R 10.1021/jacs.5c04874
%U https://bib-pubdb1.desy.de/record/639647