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O: Oberflächenphysik
O 48: Nanostructures IV
O 48.6: Vortrag
Freitag, 31. März 2006, 12:30–12:45, WIL A317
Near- and Farfield Scattering Properties of Metal Nanoparticles Excited by Radially Polarized Light — •Phillip Olk1, T. Härtling1, J. Renger1, S. Grafström1, L. M. Eng1, B. Gorzolnik2, M. Ott2, and M. Möller2 — 1Institut für Angewandte Photophysik, TU Dresden, 01062 Dresden — 2Deutsches Wollforschungsinstitut an der RWTH Aachen e.V., 52056 Aachen
We report on the optical investigation of gold nanoparticles (NPs) having a diameter between 8 and 100 nm. Single, optically isolated NPs as well as NPs in an ordered, quasi regular lattice obtained by a micellar technique [1] have been analyzed. Besides conventional linearly polarized illumination at several distinct wavelengths in the visible regime, we also consider radial polarization modes [2]. The latter polarization, if focused by a lens, causes the focal electric field vector to be perpendicular to the substrate surface. This allows us inducing an effective electrical dipole momentum µ in NPs which is parallel to the optical propagation direction k. Field calculations by means of multiple multipole method [3] and intensity measurements using dielectric tips in our scanning near-field optical microscope (SNOM) are compared with respect to the fractional content of scattered light contributing to the signal detected by the optical near field probe. The aftermath for SNOM imaging of nanoscopic metal structures on transparent substrates is discussed.
[1] J. P. Spatz et al., Langmuir 16, 407 (2000).
[2] A. A. N. Mark et al., Opt.Lett. 7, 1929 (2002).
[3] Ch. Hafner, The Generalized Multipole Technique for Computational Electromagnetics; Artech House Books, Boston (1990).