Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 50: Plasmonics & Nanooptics III: STM and Time-Resolved Methods (joint session O/CPP)

O 50.11: Vortrag

Mittwoch, 3. April 2019, 13:00–13:15, H8

Angle-resolved plasmoemission from strong SPP fields — •Pascal Dreher, David Janoschka, Michael Horn-von Hoegen, and Frank Meyer zu Heringdorf — Faculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Lotharstrasse 1-21, 47057 Duisburg, Germany

Recent efforts to observe strong-field phenomena in photoemission from metal surfaces have utilized the local enhancement of optical near-fields in nanostructures such as nanotips. On flat metal surfaces high field intensities can be achieved by femtosecond surface plasmon polariton (SPP) pulses. Here we exploit the spatio-temporal nanofocusing of SPPs in Archimedean vortex lenses [1] to achieve particularly strong plasmonic near fields with well-known field distributions on flat Au(111) surfaces. A spectroscopic photoemission electron microscope is employed to detect the electrons which are emitted from the surface by the simultaneous absorption of up to seven SPP quanta. In angle-resolved plasmoemission spectra (ARPLES) we observe signatures which can be attributed to above-threshold plasmoemission from the Au(111) Shockley surface state into SPP-dressed free electron states. The ponderomotive energy that the emitted electrons gain within the strong plasmonic nanofocus is determined from spatially-resolved plasmoemission spectra. The ponderomotive energy provides us with a direct measure for an absolute value of the transverse electric field strength of the SPP in the focus point.

[1] Spektor G, et al., Science 355, 1187 (2017)