Dresden 2009 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 9: Nanoparticles II

CPP 9.1: Vortrag

Montag, 23. März 2009, 14:00–14:15, ZEU 114

The influence of interfaces on fluorescence intermittency of single CdSe/ZnS nanocrystals — •Cornelius Krasselt, Jörg Schuster, and Christian von Borczyskowski — TU Chemnitz, Institute of Physics, 09107 Chemnitz

Fluorescence intermittency, characterized by inverse power law distributions for both the bright and dark times, appears to be a common feature of many different classes of individual emitters [1].

Meanwhile it is generally accepted, that this behaviour is due to trapping and detrapping of charges. Two basic approaches, a tunneling model by Verberk [2] and the DCET model by Tang [3] try to explain the experimental circumstances associated with the blinking phenomena.

To contribute to the current discussion of the physical nature of blinking we investigated the influence of static trap sites in the local surroundings of ZnS overcoated CdSe nanocrystals spincoated on thermally grown silicon oxide. Therefore we have modified the trap density by annealing the silcon oxide substrate to reduce the amount of trapping silanol groups on the one hand and by passivation of the silicon oxide with an organic (ODS) monolayer on the other hand. Among the modification of the blinking statistics through the ODS-monolayer we found atypical distributions for the "on" time statistics which are different from a power law or exponential behaviour.

[1] F. Cichos et al.: COCIS 12 (2007), 272

[2] R. Verberk et al.: Phys. Rev. B 66 (2002), 233202

[3] J. Tang et al.: J. Chem. Phys. 123 (2005), 054704