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O: Fachverband Oberflächenphysik
O 93: Plasmonics & Nanooptics VI: Near-Field Microscopy and Phenomena
O 93.3: Vortrag
Freitag, 5. April 2019, 11:00–11:15, H8
Anisotropic scattering from gold SNOM tips and its role in the near-field light scattering spectroscopy of single nanoparticles — •Abbas Chimeh1, Anke Korte1, Jinxin Zhan1, Jinhui Zhong1, Martin Esmann2, Nahid Talebi3, and Christoph Lienau1 — 1Universität Oldenburg — 2Centre de Nanosciences et de Nanotechnologies, Paris — 3Max-Planck Institute for Solid State Research, Stuttgart
Plasmonic nanofocusing of light using sharp conical gold tapers enables broadband coherent spectroscopy of optical near-fields around single nanoobjects with unprecedented spatial resolution . Such measurements probe how the coupling between optical near fields of tip and sample affects the light scattering spectra from the nanofocusing gold tip. Interestingly, they reveal a coupling of the sample near-fields to both longitudinal and transversal plasmonic resonances of the tip[1], allowing to unveil the vectorial nature of the near-field coupling. To understand these couplings, knowledge about the transverse resonance, corresponding to charge oscillations perpendicular to the tip axis, are needed. Here, we employed evanescent fields at a prism surface to isolate the transverse tip resonance. By polarization resolved scattering measurements, we proved the anisotropic scattering from the tip apex comprising a longitudinal broadband dipole resonance at ~800 nm and a transversal narrowband resonance at ~550 nm. This leads to a more realistic model of tip-sample coupling proposes a novel technique for broadband near-field spectroscopy in the visible spectral range.
[1] M. Esmann et al., arXiv:1801.10426 (2018).