On/"off" fluorescence intermittency of single semiconductor quantum dots

被引:476
作者
Kuno, M [1 ]
Fromm, DP
Hamann, HF
Gallagher, A
Nesbitt, DJ
机构
[1] Univ Colorado, NIST, Joint Inst Lab Astrophys, Boulder, CO 80309 USA
[2] Univ Colorado, Dept Chem & Biochem, Boulder, CO 80309 USA
关键词
D O I
10.1063/1.1377883
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
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 (tau (on)) of rapid laser absorption/fluorescence cycling, followed by (ii) sustained "off" episodes (tau (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(tau (on/off))proportional to1/tau (m)(on/off), over more than seven decades in probability density and five decades in time. Such inverse power law behavior is an unambiguous signature of highly distributed kinetics with rates varying over 10(5)-fold, in contrast with models for switching between "on" and "off" configurations of the system via single rate constant processes. The unprecedented dynamic 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. (C) 2001 American Institute of Physics.
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页码:1028 / 1040
页数:13
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