Dresden 2020 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 33: Poster Session - Plasmonics and Nanooptics: Applications and other Aspects
O 33.9: Poster
Montag, 16. März 2020, 18:15–20:00, P1C
Revealing time resolved electron-electron interactions on the nanoscale with ultrafast electron microscopy — •Andreas Wöste1, Germann Hergert1, Jan Vogelsang2, Dong Wang3, Petra Groß1, and Christoph Lienau1 — 1Universität Oldenburg — 2Lund University — 3TU Ilmenau
New spectroscopic methods providing high spatial and temporal resolution are needed to improve our understanding of the dynamics of electrons, nuclei and their spin excitations on the nanoscale. Recently ultrafast point-projection electron microscopy (UPEM) emerged as a promising approach. Here ultrashort electron wavepackets are photoemitted from a metal nanotaper by fs laser pulses. The time resolution of the laser pulses is preserved by an arbitrarily small emitter-sample distance that makes electron pulse broadening negligible. Measuring the complete electron momentum by spatially resolved time of flight detection allows mapping of the electron beam-sample interactions. Here we have employed UPEM for probing the photoemission of electrons from a gold nanoresonator with 30fs temporal and 25nm spatial resolution. We compare our experimental results with numerical simulations to reconstruct the trajectories and the contributing forces. We show how the Coulomb interactions between a single probe electron and photemitted electrons from the sample governs the time-dependent image contrast in UPEM. Our results suggest that UPEM can provide a direct measurement of the time-dependent local charge density, opening up highly interesting new perspectives for probing various types of light-induced charge-transfer processes in nanoystems.