Investigation of Energy Transfer between CdTe Nanocrystals on Polystyrene Beads and Dye Molecules for FRET-SNOM Applications

We report results on the observation of energy transfer between CdTe nanocrystals and AlexaFluor dye molecules. The nanocrystals were attached to the surface of polystyrene latex beads of 450 nm in diameter by means of the layer-by-layer technique. Energy transfer was observed as signal enhancement in confocal imaging of a single bead covered with an AlexaFluor film. This was verified by detecting quenching of the donor emission and enhancement of the acceptor emission in spectral measurements. A fluorescence-resonance energy transfer scanning near-field optical microscopy (FRET-SNOM) tip was made from a single bead coated with CdTe attached to a near-field tip. We report first results on FRET-SNOM imaging with this tip.