SAMOP 2023 – scientific programme
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MO: Fachverband Molekülphysik
MO 21: Molecular Physics with X-rays
MO 21.5: Talk
Friday, March 10, 2023, 12:00–12:15, F102
Probing the UV-induced ultrafast dynamics of thionucleobases with time-resolved x-ray absorption at the Free Electron Laser FLASH — •F Lever1,2, D Mayer1,2, D Picconi6, S Alisauskas2, F Calegari2, S Duesterer2, C Ehlert4, R Feifel3, M Kuhlmann2, T Mazza7, J Metje1, M Robinson1,2, R Squibb3, A Trabattoni2,8, M Ware5, P Saalfrank1, T Wolf5, and M Ghuer1,2 — 1Universität Potsdam, Germany — 2DESY, Germany — 3University of Gothenburg, Sweden — 4Heidelberg Institute for Theoretical Studies, Germany — 5SLAC, USA — 6University of Groningen, Netherlands — 7XFEL, Germany — 8IQO, Germany
Light-induced ultrafast reactions play a fundamental role in the photophysics of DNA, as they can lead to the formation of lesions in the genetic code. Thionucleobases are sulfur- substituted nucleobases that show an increased rate of UV-induced lesion formation. In a previous work by this group, we have investigated the photoinduced dynamics of 2-thiouracil (2-tUra) via time resolved x-ray photoemission [1,2]. In this work, we study the ultrafast dynamic 2-thiouracil in a UV-pump, x-ray probe experiment at the Free Electron Laser FLASH. The molecule is excited by the pump pulse in the S2 state (ππ* character), and its dynamic is probed by a delayed x-ray pulse that is resonant with 2p and 2s excitations of the sulfur atom. The localized probe on the sulfur allows us to image the excitation of the dark S1 (nπ) state within a 100fs time scale, and to follow oscillations in its population fraction with a period of 200fs. [1] Mayer et al. Nat Comm 13, 198 (2022) [2] Lever et al. J. Phys. B 54 014002 (2021)