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A: Fachverband Atomphysik
A 25: Poster – Cluster and Nanoparticles (joint session MO/A)
A 25.3: Poster
Wednesday, March 4, 2026, 17:00–19:00, Philo 1. OG
XUV photoionization of Microhydrated Biomolecules — •Niklas Scheel1, Ltaief Ben Ltaief1, Henrik B. Pedersen1, and Marcel C. Mudrich2 — 1Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark — 2Institute of Physics, University of Kassel, 34132 Kassel, Germany
Microhydrated biomolecules serve as valuable model systems for studying radiophysical processes in biologically relevant complexes, offering insights into the mechanisms of radiation damage in biological tissue. In this work, we present photoelectron-photoion coincidence (PEPICO) spectra of XUV-irradiated microhydrated thymine and uracil clusters, measured using the electron ion double-imaging endstation XENIA[1] at the ASTRID2 synchrotron.
We investigate outer-valence photoionization, confirming that attached water molecules stabilize the DNA bases against fragmentation[2] by acting as an efficient heat bath. At the same time, the data reveal a charge-transfer mechanism from the DNA base to the water: a charge hole initially created on a water moiety ultimately localizes on the DNA base.
Finally, we will present PEPICO spectra recorded at higher photon energies. These measurements probe inner-valence photoionization, where double ionization becomes accessible, leading to pronounced fragmentation and involving Intermolecular Coulombic Decay (ICD) as an efficient relaxation pathway.
[1] B. Bastian et al., Rev. Sci. Instrum., 2022, 93, 075110
[2] J. D. Asmussen et al., PCCP, 2023, 25, 24819-24828
Keywords: microhydrated DNA-base; velocity map imaging; synchrotron radiation; water clusters; charge transfer