Journal Article

PUBDB-2025-04604

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Unraveling the Relaxation Dynamics of Uracil: Insights from Time-Resolved X-ray Photoelectron Spectroscopy

Faccialà, D. ; Bonanomi, M. ; Tenorio, B. N. C. ; Avaldi, L. ; Bolognesi, P. ; Callegari, C. ; Coreno, M. ; Coriani, S. (Corresponding author)Extern*XFEL.EU* ; Decleva, P. ; Devetta, M. ; Došlić, N. (Corresponding author) ; De Fanis, A. ; Di Fraia, M. ; Lever, F.Extern*DESY* ; Mazza, T. ; Meyer, M. ; Mullins, T. ; Ovcharenko, Y. ; Pal, N. ; Piancastelli, M. N. ; Richter, R. ; Rivas, D. E. ; Sapunar, M. ; Senfftleben, B. ; Usenko, S. ; Vozzi, C. ; Gühr, M.Extern*XFEL.EU*DESY* ; Prince, K. (Corresponding author)Extern*XFEL.EU* ; Plekan, O. (Corresponding author)Extern*XFEL.EU*

2025
ACS Publications Washington, DC

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Please use a persistent id in citations: doi:10.1021/jacs.5c04874  doi:10.3204/PUBDB-2025-04604

Abstract: 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.

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Contributing Institute(s):

1. FS-FLASH (FS-FLASH)

Research Program(s):

1. 632 - Materials – Quantum, Complex and Functional Materials (POF4-632) (POF4-632)
2. TR-AES - Theoretical beamlines to time-resolved ultrafast Auger electron spectroscopy (101027796) (101027796)

Experiment(s):

1. SQS: Small Quantum Systems (SASE3)

Appears in the scientific report 2025

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Database coverage:
; ; ; BIOSIS Previews ; Biological Abstracts ; Chemical Reactions ; Clarivate Analytics Master Journal List ; Current Contents - Life Sciences ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; Essential Science Indicators ; IF >= 15 ; Index Chemicus ; JCR ; Nationallizenz ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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