Regensburg 2025 – scientific programme

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O: Fachverband Oberflächenphysik

O 7: Focus Session Ultrafast Electron Microscopy at the Space-Time Limit I

O 7.2: Talk

Monday, March 17, 2025, 10:45–11:00, H11

Ultrafast Electron Dynamics in Surface Plasmon Polariton Nanofoci — •Pascal Dreher, Alexander Neuhaus, Michael Horn-von Hoegen, and Frank Meyer zu Heringdorf — Faculty of Physics and Center for Nanointegration, Duisburg-Essen (CENIDE), University of Duisburg-Essen, Germany

Surface plasmon polaritons (SPPs) are collective wave-like excitations of the electron system of a metal surface that hold great potential for enhancing light-based energy conversion processes. Such enhancement is based on the efficient generation of highly-excited hot electrons via the decay of SPPs on a femtosecond timescale. To understand the corresponding microscopic dynamics, it is essential to gain a direct view into the plasmonically-generated hot electron distributions and to distinguish them from optically-generated hot electrons.

We achieve these goals by combining topologically-robust SPP nanofoci with time- and angle-resolved photoelectron spectroscopy in a photoemission microscope. This approach allows us to investigate the ultrafast non-equilibrium electron dynamics driven by SPPs on the native length-, momentum-, time-, and energy scales. We observe plasmonically-driven above-threshold electron emission, and ponderomotive shifts of the electron emission spectra provide us with a direct measure of the local SPP field strength. For different exemplary metal surfaces with distinct surface band structures we gain a direct view into the hot electron distributions generated via the coherent and incoherent decay of SPPs.

Keywords: PEEM; Surface Plasmon Polaritons; Photoemission; Hot Electrons; ARPES