On/Off Flurescence Intermittency of Single Semiconductor Quantum Dots

Published

July 1, 2001

Author(s)

M Kuno, D P. Fromm, H F. Hamann, Alan Gallagher, David Nesbitt

Abstract

Single molecule confocal microscopy is used to investigate the detailed kinetics of fluorescence intermittency in colloidal II-VI (CdSe) semiconductor quantum dots. Two distinct modes of behavior are observed corresponding to (i) sustained on episodes (τ_on) of rapid laser absorption/fluorescence cycling, followed by (ii) sustained off episodes (τ_off) where essentially no light is emitted despite continuous laser excitation. Both on-time and off-time probability densities follow an inverse power law, P (τ_on/off)varies as} l/τ^mon/off}, over more than seven decades in probability density and five decades in time. Such inverse power law behavior is an unambiguous signature of highlydistributed kinetics with rates varying over 10⁵-fold, in contrast with models for switching between on and off configurations of the system via single rate constant processes. The unprecedenteddynamic range of the current data permits several kinetic models of fluorescence intermittency to be evaluated at the single molecule level and indicate the importance of fluctuations in the quantum dot environment.

Citation

Journal of Chemical Physics

Volume

115

Issue

No. 2

Pub Type

Journals

Keywords

distributed kinetics, inverse power law, nanocrystallites, quantum dots, single molecule spectroscopy

Citation

Kuno, M. , Fromm, D. , Hamann, H. , Gallagher, A. and Nesbitt, D. (2001), On/Off Flurescence Intermittency of Single Semiconductor Quantum Dots, Journal of Chemical Physics (Accessed May 21, 2025)