Berlin 2015 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 11: Ultrafast and Nonlinear Plasmonics

O 11.5: Vortrag

Montag, 16. März 2015, 16:00–16:15, MA 004

Nonlinear Plasmo-Emission of Electrons from Focused Surface Plasmon Polaritons — •Philip Kahl, Daniel Podbiel, Andreas Makris, Simon Sindermann, Michael Horn-von Hoegen, and Frank-J. Meyer zu Heringdorf — Faculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, 47057 Duisburg, Germany

In a photoemission electron microscope with normal incidence light geometry we recently observed high-order photoemission of electrons from focused surface plasmon polaritons (SPPs) on a silver film. The SPPs are excited at concentric circular gratings, have convex wave fronts and propagate from opposite directions into the center of the inlying disc. By combining sub 20 fs laser pulses and a home-built Mach-Zehnder interferometer to a pump-probe experiment we are able to temporarily resolve the propagation of these SPPs, the formation of a standing wave at the center and the reversal of the wave front curvature of the SPPs. The fact that the circles have diameters larger than 40 microns guarantees that the laser is not present anymore when the SPPs reach the center. Hence, the electrons are emitted from the plasmonic field alone, which is why we call this effect plasmo-emission. We also captured energy-filtered photoelectron images and analyzed the kinetic energy spectra of the electrons originating from the standing wave fringes at the focal spot. The spectra indicate photoemission orders of up to five.