Frankfurt 2006 – scientific programme

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MO: Molekülphysik

MO 71: Dynamics and Spectroscopy at Interfaces

MO 71.4: Talk

Friday, March 17, 2006, 11:25–11:40, H12

Influence of the Organic Cappings of CdSe Nanoparticles on the Charge Carrier Relaxation Dynamics — •Tobias E. Schrader¹, Birgit von Holt¹, Stephan Malkmus¹, Thomas Brust¹, Wolfgang J. Schreier¹, Florian O. Koller¹, Stefan Kudera², Wolfgang Parak², and Markus Braun¹ — ¹Ludwig-Maximilians-Universität, Lehrstuhl für BioMolekulare Optik, Oettingenstr. 67, 80538 München — ²Ludwig-Maximilians-Universität, Lehrstuhl für Angewandte Physik, Amalienstr. 54, 80799 München

CdSe nanoparticles (NPs) have attracted much scientific interest because of their potential applications in labelling proteins in living cells. Organic cappings of NPs serve two purposes: Firstly they determine the surface chemistry of the NPs and therefore are a key to biological applications. Secondly they improve the fluorescence quantum yield which is crucial for the application as protein markers. With time resolved visible pump, visible and infrared probe spectroscopy we have investigated the charge carrier dynamics in NPs. With the electron acceptor naphthoquione as capping faster decay times (90 ps and 1.3 ns) of the 1 S_3/2 to 1 S_e transition at 4.6 µ m are observed as compared for the hole acceptor pyridine (120 ps and 4.1 ns). This can be interpreted by the fact that naphthoquinone provides efficient traps to the electron whose signal is observed in the IR transient.