Dresden 2026 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 24: Focus Session: Water – from Atmosphere to Space II (joint session CPP/DY)
DY 24.1: Talk
Tuesday, March 10, 2026, 11:15–11:30, ZEU/LICH
Microscopic diffusion and reactivity in aqueous solutions: photogenerated nascent halogen atoms, solvated electrons and subsequent dihalide formation — •Zhangatay Nurekeyev1,2, Hyein Hwang1,2, Fernando Rodriguez Diaz1, Mei Bai3, Michael Thorwart3, Michaela Schäfer4, Carmen Herrmann4, and Christian Bressler1,2,5 — 1Inst. of Exp. Physics, Universität Hamburg — 2The Hamburg Centre of Ultrafast Imaging (CUI) — 3I. Inst. of Theor. Physics, Universität Hamburg — 4Dept of Chemistry, Universität Hamburg — 5European XFEL, Schenefeld
The solvent plays an important role in the assembly, stability and reactivity of (bio)chemical molecules. Small changes of the caging solvent can alter the reaction outcome, but little is known about the atomic-scale solvation shell dynamics. Our approach utilizes aqueous mono-atomic halide solutes, which are transformed into nascent neutral halogen atoms upon femtosecond optical excitation together with a separated solvated electron. Combining X-ray absorption with transient optical absorption spectroscopies we monitor the subsequent diffusion-driven atom-electron recombination, each focusing on the halogen atom and on the solvated electron, respectively. We also monitor the appearance of dihalides on the tens of picosecond time scale. Using all x-ray and laser observables we deliver a new picture of the ensuing dynamics, for which the existence of the long-lived (X:e) contact pair is not required. Next steps aim to trace more complex guest-host scenarios towards functional proteins in solution.
Keywords: Ultrafast X-Ray Absorption Spectroscopy; Aqueous Solvation Dynamics; Femtosecond transient laser absorption; femto- and picosecond diffusion in water; 3D microscopic diffusion