Observing charge separation in nanoantennas via ultrafast point-projection electron microscopy

Jan Vogelsang; Germann Hergert; Dong Wang; Petra Groß; Christoph Lienau

doi:10.1038/s41377-018-0054-5

Observing charge separation in nanoantennas via ultrafast point-projection electron microscopy

Light Sci Appl. 2018 Aug 22:7:55. doi: 10.1038/s41377-018-0054-5. eCollection 2018.

Authors

Jan Vogelsang^{1

2}, Germann Hergert¹, Dong Wang³, Petra Groß¹, Christoph Lienau^{1

4}

Affiliations

¹ 1Carl von Ossietzky Universität, Institut für Physik and Center of Interface Science, 26129 Oldenburg, Niedersachsen Germany.
² 4Present Address: Department of Physics, Lund University, Box 118, 221 00 Lund, Sweden.
³ 2TU Ilmenau, Institut für Werkstofftechnik und Institut für Mikro- und Nanotechnologien, 98693 Ilmenau, Thüringen Germany.
⁴ 3Carl von Ossietzky Universität, Forschungszentrum Neurosensorik, 26129 Oldenburg, Niedersachsen Germany.

Abstract

Observing the motion of electrons on their natural nanometer length and femtosecond time scales is a fundamental goal of and an open challenge for contemporary ultrafast science^1-5. At present, optical techniques and electron microscopy mostly provide either ultrahigh temporal or spatial resolution, and microscopy techniques with combined space-time resolution require further development^6-11. In this study, we create an ultrafast electron source via plasmon nanofocusing on a sharp gold taper and implement this source in an ultrafast point-projection electron microscope. This source is used in an optical pump-electron probe experiment to study ultrafast photoemissions from a nanometer-sized plasmonic antenna^12-15. We probe the real space motion of the photoemitted electrons with a 20-nm spatial resolution and a 25-fs time resolution and reveal the deflection of probe electrons by residual holes in the metal. This is a step toward time-resolved microscopy of electronic motion in nanostructures.