Dresden 2026 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 42: Electronic structure of surfaces: Spectroscopy, surface states – Poster
O 42.1: Poster
Dienstag, 10. März 2026, 14:00–16:00, P2
Plasmonic lenses for nano-spectroscopy of Van der Waals materials — •Natalie Lehmann1, David Huber2, Daiyu Geng1, Jiabao Yang1, Stuart Parkin1, Wolf Widdra2, and Niels Schröter1 — 1Max Planck Institute of Microstructure Physics, Halle (Saale), DE — 2Martin-Luther-University Halle-Wittenberg, Halle (Saale), DE
Surface plasmon polaritons excited at the edge of Archimedean spirals carved into a gold (111) surface can be focused to a sub-micrometer spot at the spiral center [1, 2]. We aim to use this nano-focused electric field to spectroscopically investigate 2D materials, which are often only a few micrometers in size. Here we present our measurements on gold/graphene samples. Notably, the plasmonic focus remains intact, and the gold surface is effectively cleaned by the graphene; even without sputtering the gold, its characteristic surface state is observed. Furthermore, the measured k-space spectrum shows replicas of the sp orbitals above the Fermi edge, reflecting the dynamics of an excited electron system. We propose that the laser pulse is pumping the system while the plasmon is probing the excited states. These findings demonstrate the feasibility of ultrafast pumped, nano-focused spectroscopy using a single micrometer-sized laser beam.
Keywords: nanofocused photon source; plasmonics; ultrafast spectroscopy; 2D materials