TY  - JOUR
AU  - Faccialà, Davide
AU  - Bonanomi, Matteo
AU  - Tenorio, Bruno Nunes Cabral
AU  - Avaldi, Lorenzo
AU  - Bolognesi, Paola
AU  - Callegari, Carlo
AU  - Coreno, Marcello
AU  - Coriani, Sonia
AU  - Decleva, Piero
AU  - Devetta, Michele
AU  - Došlić, Nađa
AU  - De Fanis, Alberto
AU  - Di Fraia, Michele
AU  - Lever, Fabiano
AU  - Mazza, Tommaso
AU  - Meyer, Michael
AU  - Mullins, Terry
AU  - Ovcharenko, Yevheniy
AU  - Pal, Nitish
AU  - Piancastelli, Maria Novella
AU  - Richter, Robert
AU  - Rivas, Daniel E.
AU  - Sapunar, Marin
AU  - Senfftleben, Björn
AU  - Usenko, Sergey
AU  - Vozzi, Caterina
AU  - Gühr, Markus
AU  - Prince, Kevin
AU  - Plekan, Oksana
TI  - Unraveling the Relaxation Dynamics of Uracil: Insights from Time-Resolved X-ray Photoelectron Spectroscopy
JO  - Journal of the American Chemical Society
VL  - 147
IS  - 34
SN  - 0002-7863
CY  - Washington, DC
PB  - ACS Publications
M1  - PUBDB-2025-04604
SP  - 30694 - 30707
PY  - 2025
N1  - cc-by
AB  - 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.
LB  - PUB:(DE-HGF)16
C6  - pmid:40802197
DO  - DOI:10.1021/jacs.5c04874
UR  - https://bib-pubdb1.desy.de/record/639647
ER  -