Regensburg 2016 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 94: Ultrafast Surface Dynamics II
O 94.2: Vortrag
Freitag, 11. März 2016, 11:00–11:15, S054
A remotely driven ultrafast electron source — •Jan Vogelsang1, Jörg Robin1, Benedek J. Nagy2, Péter Dombi2, Daniel Rosenkranz1, Manuela Schiek1, Petra Groß1, and Christoph Lienau1 — 1Institut für Physik, Carl von Ossietzky Universität, 26129 Oldenburg, Germany — 2Wigner Research Centre for Physics, 1121 Budapest, Hungary
The combination of high spatial resolution electron microscopes and high temporal resolution laser spectroscopy promises experiments in today unexplored spatio-temporal regimes. However, in such microscopes the time resolution is so far limited to ~100fs: The distance between electron emission site and the sample must be larger than the laser focus radius. This gives rise to electron pulse broadening due to dispersion. Yet, many fundamental photoinduced processes such as coherent charge and energy transport phenomena, e.g. in solar cells, occur on few femtosecond time scales and remain hidden.
Here, we present photoelectron emission from the apex of a gold nanotaper illuminated via grating coupling at a distance of 50μm from the emission site with few-cycle laser pulses (Nano Lett. 15, 4685). Compared to direct apex illumination, we find a fifty-fold increase in electron yield. Point-projection microscopic imaging of Ag-nanowires is performed and spatial localization of the electron emission to a nanometer-sized region is demonstrated. This novel emission scheme allows for arbitrarily small distances between emission site and sample. Hence, it is of immediate interest for miniaturized electron microscopy and diffraction schemes with ultrahigh time resolution.