Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 38: Nano-optics of metallic and semiconducting nanostructures (experiments I)
O 38.2: Vortrag
Mittwoch, 25. März 2009, 15:15–15:30, SCH A216
Investigation of Geometry-dependent Dipole Coupling using Near-field Optical Microscopy of Au-nanoantennas — •Kai Braun1, Dai Zhang1, Monika Fleischer2, Dieter P. Kern2, and Alfred J. Meixner1 — 1Institut fuer Physikalische und Theoretische Chemie, Auf der Morgenstelle 8, 72076 Tuebingen — 2Institut fuer Angewandte Physik, Auf der Morgenstelle 10, 72076 Tuebingen
The plasmon coupling between two dipoles is strongly dependent on their relative positions. Theoretical simulations predicted a red shift of the localized plasmon resonance (LPR) for a dipole top-on-top geometry while a blue shift for a dipole side-by-side geometry[1]. However the corresponding experiments are hard to be realized due to the difficulties of aligning two dipoles into desired configurations. We will use a newly developed parabolic mirror assisted near-field optical microscope (SNOM) to precisely position a gold tip at different positions with respect to a gold cone. By replacing the objective lens with a parabolic mirror, this setup provides the unique possibility of obtaining a 14 times stronger electric field distribution in the longitudinal direction than that of the transversal direction[2]. Since both the gold tip and cone have strong oscillating dipoles in the longitudinal direction, this microscope allows us to study the geometry-dependent dipole coupling more accurately and flexibly. [1] Prashant K. Jain et al (2006), J. Phys. Chem. B, 110 18243-18253 [2] Fleischer M. et al (2008), Applied Physical Letters, 93 1