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Fluorescence Intermittency in Single InP Quantum Dots



M Kuno, D P. Fromm, Alan Gallagher, David Nesbitt, O I. Micic, A J. Nozik


Fluorescence kinetics of isolated colloidal InP quantum dots (Qds) are investigated for the first time via confocal single molecule microscopyFluorescenceintermittency or blinking is observed in all QD's sampled, characterized by abrupt chanc,yes between episodes of absorption/laserinduced fluorescence and periods of darkness despite continuous laser excitation of the nanoparticle. Analysis of fluorescence trajectories forisolated InP QDs reveals an inverse power law (variation} 1/τ/m/) in both the on-time and off-time probability densities [P(τon) and P(τoff)], with average power law exponents of mon nearly equal to} -2.02 (2) and moff nearly equal to} -1.5 (1). In the context of QD ionization models for blinking, such intrinsically non-exponential kinetics requires highly distributed rate constants (over 102-104 fold) for ejection and recombination dynamics of electron/hole pairs from single InP QD's. More fundamentally, the inverse power law in both P(τon) and P(τoff) is qualitatively inconsistent with a static distributionof external sites for electron/hole trapping, and highlights the critical role of time dependent fluctuations in the local QD nanoenvironment.
Nano Letters
No. 10


fluorescence intermittency, opoelectronics, photoionization, quantum dots


Kuno, M. , Fromm, D. , Gallagher, A. , Nesbitt, D. , Micic, O. and Nozik, A. (2001), Fluorescence Intermittency in Single InP Quantum Dots, Nano Letters (Accessed April 25, 2024)
Created September 30, 2001, Updated October 12, 2021