"On"/"off" fluorescence intermittency of single semiconductor quantum dots
"On"/"off" fluorescence intermittency of single semiconductor quantum dots
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DOI：
10.1063/1.1377883
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发表时间：
2001-07-08
影响因子：
4.4
通讯作者：
Nesbitt, DJ
中科院分区：
文献类型：
--
作者：
Kuno, M;Fromm, DP;Nesbitt, DJ
用单分子共聚焦显微镜研究了胶体II-VI(CdSe)半导体量子点的荧光间歇动力学。观察到两种不同的行为模式，对应于(I)快速激光吸收/荧光循环的持续“开启”事件(tau(On))，随后是(Ii)持续的“关闭”事件(tau(Off))，其中尽管连续的激光激发，基本上不发射光。在超过70年的概率密度和50年的时间内，开启时间和关闭时间的概率密度都遵循与1/tau(M)(开启/关闭)成正比的反指数规律。这种逆幂定律行为是高度分布动力学的明确特征，速率变化超过10(5)倍，而不是通过单速率恒定过程在系统的“开”和“关”配置之间切换的模型。当前数据前所未有的动态范围使几种荧光间歇动力学模型能够在单分子水平上进行评估，并表明量子点环境中波动的重要性。(C)2001年美国物理研究所。
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.