Dresden 2006 – wissenschaftliches Programm

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O: Oberflächenphysik

O 48: Nanostructures IV

O 48.7: Vortrag

Freitag, 31. März 2006, 12:45–13:00, WIL A317

Optical Properties of Gold Nanoparticles close to a Gold Surface — •Adriana Rueda, Marco Stemmler, Noelia Bocchio, and Max Kreiter — Max-Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany

Studies of the optical properties of spherical gold nanoparticles placed close to a gold flat surface will be discussed. According to electromagnetic theories [1] particles with localized electromagnetic resonances like gold nanoparticles can interact with a metal surface producing a special kind of resonance (called the gap mode) generating large enhancements of the near field in the gap between the particle and the surface. This effect was studied in some detail experimentally in an inorganic system by Okamoto et al. [2]. As a well-defined model system we use gold nanoparticles with diameters in the range of 20-250 nm linked to a thin gold film deposited onto a glass substrate by means of an organic self-assembled monolayer of linker molecules, allowing for a selective positioning of functionalities as fluorophores in the gap. The resulting multilayered system was studied with multiwavelength surface plasmon resonance measurements which are highly sensitive to effects taking place at the surface. If the gold nanoparticles are regarded as an effective layer [3], these measurements allow for the detection of resonances in the polarisability due to gap excitation.

[1] P.K. Aravind and H. Metiu, Surface Science 124, 506 (1983)

[2] T. Okamoto and I. Yamaguchi, J.Phys.Chem. 107 (38), 10321 (2003)

[3] M.A.Plunkett et al., Langmuir 19, 6837 (2003)