Berlin 2015 – scientific programme
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O: Fachverband Oberflächenphysik
O 29: Near-Field Microscopy
O 29.5: Talk
Tuesday, March 17, 2015, 15:00–15:15, MA 042
Broadband nanospectroscopy with metallic, nanofocusing SNOM tapers — •Martin Esmann1, Simon F. Becker1, Heiko Kollmann1, Petra Groß1,2, Ralf Vogelgesang1, and Christoph Lienau1 — 1Carl von Ossietzky Universität, 26111 Oldenburg, Germany — 2Universität Osnabrück, 49076 Osnabrück, Germany
Broadband extinction spectroscopy with nanoscale lateral resolution demands methods with low background signals. To this end, a very promising approach is the concept of adiabatic nanofocusing in metallic nanotapers[1,2]. Surface plasmon polaritons (SPPs) are excited on a grating coupler and result in strongly confined near-fields at the taper apex.
Here, we use single crystalline gold tapers as scanning near-field optical microscopy (SNOM) probes[3] in combination with broadband white-light excitation. We test this approach by imaging the spectrally dependent near-field enhancement over a planar gold film. On this basis, we perform extinction spectroscopy on individual nanoantennas with a spectral bandwidth of several hundreds of nanometers. The very high lateral resolution of our approach allows us to spectrally image the mode profiles of such individual nanostructures. In combination with ultrashort pulses this method can be straightforwardly extended to the investigation of coherences in quantum and biological systems.
[1] M.I. Stockman, PRL 93, 137404 (2004); [2] S. Schmidt et al., ACS Nano 6, 6040 (2012); [3] M. Esmann et al., BJ Nano 4, 603 (2013).