Dresden 2003 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 22: POSTER C

CPP 22.29: Poster

Donnerstag, 27. März 2003, 12:00–14:00, ZEU/250

Blinking Statistics of Individual CdSe Nanocrystals with attached Porphyrin Molecules — •Frank Cichos¹, Christian von Borczyskowski¹, Eugene Petrov¹, Edward Zenkevich², Alexander Shulga², and Sergej Gaponenko² — ¹Institut für Physik 122501, TU Chemnitz, 09107 Chemnitz, Germany — ²Institute of Molecular and Atomic Physics and B.I. Stepanov Institute of Physics, National Academy of Ssciences, 70 F. Skaryna Avenue, 220072 Minsk, Belarus

Semiconductor nanoparticles obey an emission intermittency, which is similar to organic molecules. However the dark state of nanoparticles is supposed to be a charged state, where one of the excited carriers is ejected from the particle into a trap state in the environment. In our experiments we create a well defined trap state in the particle environment by binding pyridyl containing porphyrin molecules as electron acceptors to CdSe/ZnS core shell nanoparticles. We study the blinking statistics of individual CdSe nanocrystals with and without porphyrins in a wide field microscopy setup. Both particle types attached show the common power law in the statistics of on and off times of the emission intermittency. While the blinking statistics of different samples of the same particle batch show a reproducible exponent, the exponent of the porphyrin covered particles changes to lower values. As a consequence, the average duration of off times of these particles is shifted to longer values. The results indicate, that the bound porphyrin molecules act as as an additional trap for ejected electrons. The results are consistent with ensemble measurements of emission quenching.