Berlin 2005 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 36: Single molecules II

CPP 36.2: Vortrag

Mittwoch, 9. März 2005, 11:30–11:45, TU C243

A Common Source for Emission Intensity Fluctuations of Single Chromophores — •Frank Cichos¹, Abey Issac^2,1, Jörg Schuster², and Christian von Borczyskowski² — ¹Photonik und Optische Materialien, Institut für Physik, TU Chemnitz, 09107 Chemnitz — ²Optische Spektroskopie und Molekülphysik, Institut für Physik, TU Chemnitz, 09107 Chemnitz

The emission intermittency of quantum dots and dye molecules is one of the striking phenomena of single quantum objects. Its occurrence is unwanted and wanted at the same time since it intermits the observation of the chromophore but resembles to be one of the simplest switching events possible in a nano-object. However, both issues require control over the intermittency, which has to be based on a detailed understanding of this phenomenon.

Our experimental results demonstrate, that both, emission intensity fluctuations of organic dye molecules and semiconductor quantum dots reveal power law statistics at timescales far beyond typical triplet state lifetimes. The similarity of the blinking statistics for both types of emitters suggests a common source. Experiments on single emitters in various dielectric environments reveal, that the dark periods during the intensity fluctuations are related to an ionization of the emitter including a self-trapping of charges in the environment. The duration of the bright periods is however largely uncoupled from the dielectric properties of the environment and involves intermediate states of the quantum dot or dye molecule.