Berlin 2015 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 50: Coupled Nanostructures and Light Localization
O 50.8: Vortrag
Mittwoch, 18. März 2015, 12:15–12:30, MA 043
Real space imaging of nano-tip plasmons using electron energy-loss spectroscopy — •Thorsten Weber1, 2, Benjamin Schröder3, Sergey Yalunin3, Christian Matyssek4, Thomas Kiel4, Felix von Cube1, 2, Stephan Irsen2, Kurt Busch4, 5, Stefan Linden1, and Claus Ropers3 — 1Physikalisches Institut, Rheinische Friedrich-Wilhelms-Universität Bonn, Germany — 2Research center caesar, center of advanced european studies and research, Bonn, Germany — 3IV. Physikalisches Institut, Georg-August-Universität Göttingen, Germany — 4Institut für Physik, Humbold-Universität zu Berlin, Germany — 5Max-Born-Institut, Berlin, Germany
Focusing light beyond the diffraction limit is of great interest in photonics. Metallic nano-tips offer the ability to concentrate light in nanometric volumes on femtosecond timescales using adiabatic compression of surface plasmon polaritons, facilitating applications in tip-enhanced Raman scattering, optical near field microscopy or ultra fast photoemission. Here, we show real-space imaging of surface plasmon polaritons on a gold nano-tip using electron energy-loss spectroscopy (EELS) in combination with scanning transmission electron microscopy. We demonstrate the predicted nanofocussing towards the apex and measure the local dispersion relation of the plasmon. The observations are in good agreement with ab-initio electrodynamic computations via the discontinous-Galerkin time-domain method and a semi-analytical model including reflection at the apex and higher order azimuthal modes.