Berlin 2015 – scientific programme
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O: Fachverband Oberflächenphysik
O 75: Plasmonics and Nanooptics
O 75.2: Poster
Wednesday, March 18, 2015, 18:15–21:00, Poster A
Super-resonant infrared near-field microscopy — •Denny Lang1,2, Tino Uhlig1, Susanne C. Kehr1, Manfred Helm2, and Lukas M. Eng1 — 1Institut für Angewandte Physik, Technische Universität Dresden, 01069 Dresden — 2Institut für Ionenstrahlphysik und Materialforschung, Helmholtz-Zentrum Dresden-Rossendorf, 01314 Dresden
Scattering-type scanning near-field optical microscopy (s-SNOM) is an AFM-based technique for achieving nanoscale resolution even at infrared wavelengths [1]. s-SNOM thus is of valuable impact when e.g. investigating low-dimensional conductors or semiconductors. In order to enhance the signal strength we face two options, by either tuning the tip or sample into resonance using appropriate or tunable laser light sources.
In this work we use a CO2-laser with a tunable center wavelength from 9.7 µm to 11.3 µm as an infrared excitation source in combination with self-prepared AFM particle-tips as probes [2]. The tip particles consist of spherical SiC, Si3N4 or SiO2 nanoparticles with a diameter of ∼60 nm. Those materials show phonon resonances in or around the CO2-laser wavelength range and thus enhance the signal signifi- cantly. We explore here the scenario when using both resonant tips and samples, hence resulting in a tip-sample coupled super-resonance. Accordingly, a significantly increased near-field image contrast and resolution is expected in this case.
[1] S.C. Kehr et al., Nat. Commun. 2, 249 (2011).
[2] M.T. Wenzel et al., Opt. Express 16, 12302 (2008).