Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

MO: Fachverband Molekülphysik

MO 20: Transport and Spectroscopy in Molecular Nanostructures II (related to SYMN, jointly with CPP)

MO 20.6: Vortrag

Donnerstag, 17. März 2011, 11:45–12:00, TOE 317

Modeling the blinking dynamics of single CdSe/ZnS quantum dots probing their local environment — •Cornelius Krasselt¹, Robert Schmidt¹, Jörg Schuster^1,2, and Christian von Borczyskowski¹ — ¹Institute of Physics and nanoMA (Center for nanostructured Materials and Analytics), Chemnitz University of Technology, Germany — ²now: Fraunhofer Institute ENAS

Fluorescence intermittency, also known as blinking, appears to be a common feature of many different classes of individual emitters like semiconductor quantum dots. Generally it is characterized by inverse power law distributions for both the on- and off- times [1] which are due to trapping and detrapping processes of charges in- and outside the quantum dots, respectively.

This contribution discloses the influences of the local environment surrounding ZnS coated CdSe quantum dots on silicon oxide on their blinking dynamics. We present atypical distributions for the on-time statistics which show deviations from the expected power law behaviour only seen at the beginning of the statistics. These deviations correlate to the local density of hydroxyl groups on silicon oxide but are also measured in polymers such as PS and PVA. Furthermore we are able to resolve the intensity levels of quantum dot time traces via intensity-changepoint analysis observing an increasing density of bright intensity levels in case of enhancing on-time deviations accompanied by longer exciton lifetimes. All results are discussed in terms of a model concerning hole trapping processes within the quantum dots.

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