Rostock 2019 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 30: Atomic Physics, Molecular Physics, and Quantum Optics with X-ray FELs (joint session MO/A)
A 30.5: Vortrag
Donnerstag, 14. März 2019, 11:30–11:45, S HS 002 Biologie
Detecting ultrafast hole dynamics in water using x-ray transient absorption — •Caroline Arnold1,2,4, Ludger Inhester1, Ralph Welsch1,4, Linda Young3, and Robin Santra1,2,4 — 1Deutsches Elektronensynchrotron DESY, Hamburg — 2Universität Hamburg — 3Argonne National Laboratory, USA — 4Centre for Ultrafast Imaging, Hamburg
The dynamics that unfold in aqueous solutions on a molecular time scale are of direct relevance to biological and chemical processes. For example, radiation damage in biological tissues is caused by the photoionization of liquid water. The early steps of radiation damage can be understood by following the electron-hole pair dynamics with femtosecond time-resolution. While the hydrated electron has been addressed in experiments, the dynamics of the residual cation remains elusive. Today’s XFEL sources allow to detect the hole by resonant x-ray absorption spectroscopy at the oxygen K-edge with femtosecond time resolution.
We present a theoretical, ab initio description of the hole dynamics in ionized water and the resulting x-ray absorption spectra. To this end, we consider excited-state molecular dynamics in liquid water following the removal of an electron from the valence band in a quantum-classical, QM/MM scheme including non-adiabatic transitions. We present first results on time-resolved x-ray absorption spectra in the first 100 femtoseconds following photoionization and discuss their use as a probe for hole dynamics.