Regensburg 2004 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 44: Poster II
HL 44.36: Poster
Donnerstag, 11. März 2004, 16:30–19:00, Poster A
Influence of size and shell on blinking dynamic of CdSe quantum dots — •Kirill V. Anikin1, Andrei Yu. Kobitski1, Colin D. Heyes1, Vladimir V. Breus1, and G. Ulrich Nienhaus1,2 — 1Department of Biophysics, University of Ulm, D - 89069 Ulm, Germany — 2Department of Physics, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
Quantum dots are promising for many scientific and industrial applications, one of which is using them as fluorescence labels in the study of biological species by means of single molecule spectroscopy. They are bright, posses the possibility to change the emission color by variation of size, can be made biocompatible, and are much more photostable than commercially available dyes. However, they have a disadvantage which is intrinsic for single molecules: blinking, the intermission of luminescence intensity under CW excitation.
In this work we perform a systematic study of the blinking dynamics (on/off-time distribution) of single uncapped CdSe QDs and capped CdSe/ZnS core-shell QDs immobilized in a poly(methyl methacrylate) (PMMA) matrix as a function of core size, thickness of shell(from 0 to 4 monolayers) and excitation intensity to understand the basic mechanisms governing the blinking. As method of investigation we have chosen Total Internal Reflection Fluorescence Microscopy (TIRFM) because this technique provides the advantage of recording the time-resolved fluorescent signal of many single QDs simultaneously, thus allowing data with high statistical confidence to be obtained in a relatively short time.