Berlin 2018 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 63: Plasmonics and nanooptics: Applications and other aspects I

O 63.2: Vortrag

Mittwoch, 14. März 2018, 12:15–12:30, MA 041

Ultrafast point-projection electron microscopy with a time-of-flight delay-line detector — •Germann Hergert¹, Andreas Wöste¹, Jan Vogelsang¹, Dong Wang², Petra Groß¹, and Christoph Lienau¹ — ¹Institut für Physik, Carl von Ossietzky Universität, 26129 Oldenburg, Germany — ²Institut für Werkstofftechnik, TU Ilmenau, 98693 Ilmenau, Germany

Observing electrons move on their natural few-fs-time and nm-spatial regime requires ultrahigh resolution. In laser-triggered ultrafast electron microscopes the temporal resolution typically is limited to around 100fs by the mesoscopic propagation distance of the probing electron pulse to the sample, which leads to pulse broadening due to dispersion.

One way to overcome this broadening is to reduce the distance between emitter and sample. An already known solution to this is adiabatic nanofocusing of surface plasmon polaritons along the shaft of a sharp metallic taper. This prevents direct illumination of a sample and allows minimal distances to the emitter. Implementing this method into an ultrafast point-projection electron microscope (UPEM) allows imaging with unprecedented spatio-temporal resolution. We equip the system with a time-of-flight delay-line detector to gain additional information about the electron energies for studying the interaction between electrons and localized electric fields, e.g. around nanostructures.

Here, we present such an UPEM setup with high spatio-temporal resolution. We show first results, where we photoemit electrons from nanometer-sized plasmonic antennas with femtosecond laser pulses and observe their motion with 20-nm spatial and 25-fs temporal resolution.