Regensburg 2025 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 10: Focus Session Ultrafast Electron Microscopy at the Space-Time Limit II

O 10.1: Hauptvortrag

Montag, 17. März 2025, 15:00–15:30, H2

Probing coherent optical emission processes with ultrafast scanning electron microscopy — •Albert Polman — NWO Institute AMOLF, Amsterdam, the Netherlands

High-energy electron beams are unique probes of optical materials properties as their time-varying electric field can create strong materials polarizations. The subsequent light emission (cathodoluminescence, CL) provides a fingerprint of the local optical density of states at the nanoscale.

CL from plasmonic and dielectric nanostructures has a coherent phase relation with the excitation process, which enables self-referenced measurements to perform holography and metrology. Electron excitation of semiconductors creates a sequence of fs-ps-ns materials excitations, that lead to bunched CL photon emission.

New developments in ultrafast electron microscopy enable the creation of picosecond electron pulses and pump-probe spectroscopy where light and electrons serve as pump and probe or vice versa. The interaction of pulsed electrons with optical metasurfaces enables novel ways to shape the quantum mechanical electron wavepackets in space and time and may eventually create entirely new forms of ultrafast materials spectroscopy.

Keywords: electron beams; cathodoluminescence; nanophotonics