Mainz 2026 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 30: Poster – Molecular Spectroscopy

MO 30.2: Poster

Donnerstag, 5. März 2026, 17:00–19:00, Philo 1. OG

High-Resolution Excitation Spectroscopy of Acridine Derivatives and their Complexes with Water — •Kaleb Strahringer, Aleksandr Demianenko, Frank Stienkemeier, and Sebastian Hartweg — Universität Freiburg, Phys. Institut, 79104 Freiburg

Using sunlight to split water into oxygen and hydrogen offers a sustainable route to producing hydrogen as a source of energy from abundant resources. While directly breaking the H-O bond requires 6.66 eV, excitation of a chromophore that mediates the reaction via electron-driven proton transfer (EDPT) reactions, can significantly reduce the necessary photon energy. Potential chromophores include aromatic N-heterocycles that have been studied experimentally [1] and theoretically [2]. Larger polycyclic chromophores are predicted to require lower excitation energies to enable EDPT reactions. For this reason, and as a prerequisite for future time-resolved studies, we plan to investigate promising acridine derivatives and their complexes with water with high-resolution excitation spectroscopy. In our setup, we use helium nanodroplet isolation spectroscopy to efficiently cool isolated chromophore molecules and form their complexes with water under controlled conditions. Using high-resolution nanosecond-laser fluorescence spectroscopy and resonance-enhanced multiphoton ionization (REMPI) schemes to probe dark states, we aim to obtain detailed insights into the chromophores' vibronic structure and relaxation pathways, and how they are affected by the presence of water.

[1] Esteves-López et al., Phys. Chem. Chem. Phys. 18 (2016) 25637

[2] Liu et al., Chem. Phys. 464 (2016) 78

Keywords: Helium Nanodroplet Isolation; Acridine Dyes; Laser Induced Fluorescence; Photocatalytic Water Splitting; Electron-driven Proton Transfer