Dresden 2026 – scientific programme

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O: Fachverband Oberflächenphysik

O 38: Ultrafast electron dynamics at surface and interfaces II

O 38.1: Talk

Tuesday, March 10, 2026, 10:30–10:45, TRE/MATH

Ultrafast momentum microscopy of exciton dynamics at ZnO surfaces — •Hashima Marukara, Paul Werner, Jan Philipp Bange, G S Matthijs Jansen, Wiebke Bennecke, Junde Liu, and Stefan Mathias — Georg-August-Universität Göttingen, I. Physikalisches Institut, Germany

ZnO is a prototypical wide-band-gap material with long-lived excitons, making it a central platform for modern optoelectronic and catalytic technologies, especially for investigating exciton-related phenomena [1]. Excitons*bound electron*hole pairs that can exist in various forms near the surface, significantly shape the material*s optical and electronic response and play an essential role in interfacial energy-conversion processes [2]. However, studies that directly characterize these excitons, particularly if they are defect-mediated, localized or mobile, or predominantly Frenkel- or Wannier-type, remain limited.

Here we address these questions using time-resolved momentum microscopy to map the fingerprints of excitons in energy, momentum and time [3]. We present first experimental momentum-space maps of the ZnO(10-10) surface exciton states and track their real-time evolution following photoexcitation. We observe clear signatures of surface exciton formation, including their emergence in the unoccupied band structure and their subsequent relaxation dynamics on ultrafast timescales.

[1] Gierster et al., Nat Commun 12, 978 (2021) [2] Deinert et al., Phys. Rev. Lett. 113 057602 (2014) [3] Bennecke et al., Nature Phys. (2025), https://doi.org/10.1038/s41567-025-03075-5

Keywords: Ultrafast momentum microscopy; trARPES; exciton dynamics