%0 Journal Article
%A Lever, Fabiano
%A Picconi, David
%A Mayer, Dennis
%A Alisauskas, Skirmantas
%A Calegari, Francesca
%A Duesterer, Stefan
%A Feifel, Raimund
%A Kuhlmann, Marion
%A Mazza, Tommaso
%A Metje, Jan
%A Robinson, Matthew
%A Squibb, Richard
%A Trabattoni, Andrea
%A Ware, Matthew
%A Saalfrank, Peter
%A Wolf, Thomas
%A Guehr, Markus
%T Direct observation of ππ<sup>*</sup> to nπ<sup>*</sup> transition in 2-thiouracil via time resolved NEXAFS spectroscopy
%J The journal of physical chemistry letters
%V 16
%@ 1948-7185
%C Washington, DC
%I ACS
%M PUBDB-2024-01318
%P 4038 - 4046
%D 2025
%X The photophysics of nucleobases has been the object of both theoretical and experimental studies over the past decades, due to the challenges posed by the non-BOA (Born-Oppenheimer Approximation) dynamics in their relaxation pathway. In this context, the ultrafast dynamics of 2-thiouracil has been investigated with a time-resolved NEXAFS study at the Free Electron Laser FLASH.We show that x-ray absorption spectroscopy can be used to observe electronic transitions in ultrafast molecular relaxation. We use a uv-pump / x-ray probe scheme to measure the changes induced by photoexcitation to the x-ray absorption at the sulfur 2s and 2p edges, identifying absorption features corresponding to the S2 (ππ*) and S1 (nπ*) electronic states. We observe a delay of 102 ± 11 fs in the population of the nπ* state with respect to the initial optical excitation. We furthermore identify the presence of coherent oscillations in the absorption signal that match a similar observation in our previous x-ray photoelectron spectroscopy study.
%F PUB:(DE-HGF)16
%9 Journal Article
%$ 40232202
%U <Go to ISI:>//WOS:001467403900001
%R 10.1021/acs.jpclett.5c00544
%U https://bib-pubdb1.desy.de/record/605144