Dresden 2009 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 36: Particles and clusters

O 36.3: Vortrag

Mittwoch, 25. März 2009, 15:30–15:45, SCH A01

Metal-Nanoparticle-Induced Fluorescence Enhancement from a Single Layer of Dye Molecules — •René Schneider, Thomas Härtling, Philipp Reichenbach, and Lukas M. Eng — Institute of Applied Photophysics, TU Dresden, Germany

We investigate the applicability of metal nanoparticles (MNPs) to enhance the fluorescence signal of a monolayer of dye molecules. The dependence of the signal strength on the distance between the molecules in the layer and a single MNP is examined by means of a scanning near-field optical microscope (SNOM), the scanning probe of which is equipped with a single gold nanoparticle [1]. This setup allows to change the separation between the particle and the illuminated sample and monitor the optical response of the system under various illumination conditions.

We show that single 80 nm gold particles embedded in immersion oil enhance the fluorescence signal from a layer of molecules when illuminated with a Gaussian focus. By changing the separation between MNP and sample we observed a modulated fluorescence signal. This modulation is induced by the interference of incoming and scattered light of the particle. The results of analogous investigations using radially polarized light will be presented and compared with the previous measurements.

[1] M. T. Wenzel, T. Härtling, P. Olk, S. C. Kehr, S. Grafström, S. Winnerl, M. Helm, and L. M. Eng, Opt. Express, 16, 12302 (2008).