München 2004 – wissenschaftliches Programm
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MO: Molekülphysik
MO 18: Stossprozesse, Energietransfer
MO 18.2: Vortrag
Donnerstag, 25. März 2004, 16:45–17:00, HS 355
FRET-based Scanning Near-Field Optical Microscopy — •Felix Müller, Stephan Götzinger, and Oliver Benson — Nano-Optik, Institut für Physik, Humboldt-Universität zu Berlin, D-10117 Berlin
We investigate Förster Resonant Energy Transfer (FRET) by means of Scanning Near-Field Optical Microscopy (SNOM). Our setup allows to actively control the distance between the acceptor and donor and thus to investigate the strong distance dependence of the energy transfer efficiency. As donor and acceptor we use CdTe nanocrystals1 and organic dye molecules (Alexa Fluor 633). The spectral parameters of the donor-acceptor pair are shown to be appropriate for FRET.
We produce an active SNOM probe by attaching a single 500 nm sized colloid covered with a layer of nanocrystals. This donor probe can be positioned at will above a cover slip coated with a thin layer of the acceptor molecules. Within a tip-sample distance of a few nanometers, a sudden increase in the acceptor’s optical signal is observed. This effect gives strong evidence for FRET.
Accordingly, we propose a novel FRET-SNOM geometry. We discuss the improved
reliability, stability and resolution of this system.
provided by N. Gaponik, H. Weller, Univ. Hamburg