TY  - JOUR
AU  - Lever, Fabiano
AU  - Picconi, David
AU  - Mayer, Dennis
AU  - Alisauskas, Skirmantas
AU  - Calegari, Francesca
AU  - Duesterer, Stefan
AU  - Feifel, Raimund
AU  - Kuhlmann, Marion
AU  - Mazza, Tommaso
AU  - Metje, Jan
AU  - Robinson, Matthew
AU  - Squibb, Richard
AU  - Trabattoni, Andrea
AU  - Ware, Matthew
AU  - Saalfrank, Peter
AU  - Wolf, Thomas
AU  - Guehr, Markus
TI  - Direct observation of ππ<sup>*</sup> to nπ<sup>*</sup> transition in 2-thiouracil via time resolved NEXAFS spectroscopy
JO  - The journal of physical chemistry letters
VL  - 16
SN  - 1948-7185
CY  - Washington, DC
PB  - ACS
M1  - PUBDB-2024-01318
SP  - 4038 - 4046
PY  - 2025
AB  - 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.
LB  - PUB:(DE-HGF)16
C6  - 40232202
UR  - <Go to ISI:>//WOS:001467403900001
DO  - DOI:10.1021/acs.jpclett.5c00544
UR  - https://bib-pubdb1.desy.de/record/605144
ER  -