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O: Oberflächenphysik
O 47: Rastersondentechniken III
O 47.3: Talk
Tuesday, March 8, 2005, 16:15–16:30, TU EB202
Resonant light scattering by near-field induced localized phonon polaritons — •Jan Renger1, Stefan Grafström1, Lukas M. Eng1, and Rainer Hillenbrand2 — 1Institute of Applied Photophysics, University of Technology Dresden, D-01062 Dresden — 2Nano-Photonics Group, Max-Planck-Institut für Biochemie, Am Klopferspitz 18, D-82152 Martinsried
In the vicinity of a SiC surface the scattering of light at a metallic nanoparticle shows a strong peak around the surface phonon polariton resonance of the SiC substrate [1] in the mid-infrared spectral region. Close to the surface the polarized particle couples to localized phonon polaritons. This near-field interaction shifts the peak to lower frequencies and causes a splitting into two modes for distances below 5 nm. We analyze this phenomenon by applying an accurate numerical 3D model based on the multiple-multipole method. The results are compared with the predictions of the analytical dipole model as frequently used to explain the contrast in aperture-less scattering- type scanning near-field optical microscopy. We find a qualitative agreement but the dipole model turns out to underestimate the spectral shift quantitatively, which is significant for small separations between the sphere and the SiC interface.
[1] R. Hillenbrand, T. Taubner, and F. Keilmann, Nature 418, 159 (2002).