Speaker
Description
We probe the UV induced relaxation of the thionucleobase 2-thiouracil. This class of molecules shows an efficient and ultrafast relaxation into long-lived triplet states, contrasting with the ultrafast relaxation to the ground states observed in canonical nucleobases. This gives rise to interesting applications as photoinduced-cross linkers as well as problems related to its current use of thionucleobases as medication.
We investigate the dynamics of 2-thiouracil via x-ray probing at the sulfur L-edge using the new URSA-PQ instrument for gas-phase spectroscopy at FLASH [1]. We have performed time-resolved Auger spectroscopy that exhibits features of the expanding C-S bond of the molecule after photoexcitation [1]. Besides, we have performed sulfur 2p photoelectron spectroscopy that contains rich information about the electronic relaxation path. We interpret these results by a UV induced change of the local charge at the sulfur atom, which changes as the molecule relaxes from its photoexcited electronic state to lower-lying product states.
[1] URSA-PQ: a mobile and flexible pump-probe instrument for gas phase samples at the FLASH free electron laser, J. Metje, F. Lever, D. Mayer, R. J. Squibb, M. S. Robinson, M. Niebuhr, R. Feifel, S. Düsterer, M Gühr, Applied Sciences 10, 7882 (2020)
[2] Ultrafast dynamics of 2-thiouracil investigated by time-resolved Auger spectroscopy
F. Lever, D. Mayer, D. Picconi, J. Metje, S. Alisauskas, F. Calegari, S. Düsterer, C. Ehlert, R. Feifel, M. Niebuhr, B. Manschwetus, M. Kuhlmann, T. Mazza, M. S. Robinson, R. J. Squibb, A. Trabattoni, M. Wallner, P. Saalfrank,T. J. A. Wolf, M Gühr, J. Phys. B 54, 014002 (2020)
Short info on the speaker:
PhD physics, FU Berlin (2005)
Postdoctoral Scholar Stanford University (2006-2007)
Staff, Associate and Senior Staff Scientist, SLAC (2007-2015)
Lichtenberg Professor (2015-2020)
Research fields: ultrafast x-ray science, molecular photoinduced dynamics, ultrafast electron scattering
Markus Gühr, Experimental Quantum Physics Group, Physics and Astronomy Institute, Universität Potsdam
www.exp-quantum.org
mguehr@uni-potsdam.de
