Berlin 2008 – scientific programme
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O: Fachverband Oberflächenphysik
O 77: Methods: Scanning Probe Techniques I
O 77.5: Talk
Thursday, February 28, 2008, 16:30–16:45, MA 041
Resolution improvement for mid infrared nearfield optical microscopy through gold nanoparticle scatterers — •Marc Tobias Wenzel1, Susanne C. Schneider1, Lukas M. Eng1, Stephan Winnerl2, and Manfred Helm2 — 1Institute of Applied Photophysics, Technische Universität Dresden, 01062 Dresden — 2Institute of Ion Beam Physics and Materials Research, Forschungszentrum Dresden-Rossendorf, 01314 Dresden
We present the implementation of 80 nm sized gold nanoparticles as tips for scattering nearfield optical investigations in the mid IR using a tunable free electron laser source (available frequency range 4 - 200 µ m). At IR frequencies an efficient electric field confinement is advantageous for deducing the local dielectric and optical properties such as phonon vibration modes and local refractive indices of nm-sized implants. Our approach is based on confining the scattering volume by using gold-nanoparticles of different diameters. First, every single nanoparticle is characterized optically and then attached to an ordinary AFM cantilever tip. The cantilever is used as a spatial manipulator for the metal-nanoparticle scatterer in an AFM based scattering scanning nearfield optical microscope set-up (s-SNOM). Using these enhanced tips, we optically inspected anisotropic dielectrics at mid IR frequencies. As a result, we obtain a considerably improved confinement of the optical signal as demonstrated by tip/sample approach curves and theoretical modelling. Our experimental findings are in good agreement with our dipolar scattering theory.