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CPP: Chemische Physik und Polymerphysik

CPP 16: Time-resolved phenomena

CPP 16.2: Talk

Monday, March 7, 2005, 16:45–17:00, TU C243

Distance dependence of fluorescence quenching by gold nanoparticles — •M. Ringler¹, E. Dulkeith¹, T. A. Klar¹, J. Feldmann¹, A. Muñoz Javier², and W. J. Parak² — ¹Photonics and Optoelectronics Group, Physics Department and CeNS, Ludwig-Maximilians-Universität München, Germany — ²Center for NanoScience (CeNS), Ludwig-Maximilians-Universität München, Germany

Hybrid systems of gold nanoparticles (AuNPs), chromophores, and oligonucleotides are of current interest in biophotonics. A common feature of chromophore - AuNP composites is that the AuNPs can serve as ultra efficient quenchers of molecular excitation energy, outranging the quenching efficiency of organic acceptor molecules. The fluorescence quantum yield of dye molecules attached to gold nanoparticles via single stranded DNA (ssDNA) spacers is measured for Cy5-nanoparticle distances between 2.2 and 16.2 nm. Different numbers of ssDNA per nanoparticle allow to fine-tune the distance. Radiative and nonradiative molecular decay rates are determined using time resolved photoluminescence spectroscopy. A reduced quantum yield is found for all distances.