Nonexponential "blinking" kinetics of single CdSe quantum dots: A universal power law behavior
Nonexponential "blinking" kinetics of single CdSe quantum dots: A universal power law behavior
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DOI：
10.1063/1.480896
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发表时间：
2000-02-15
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
利用单分子共聚焦显微镜研究了在488nm激发下ZnS包覆CdSe量子点（QDs）的荧光间歇性。共聚焦装置允许“开”和“关”时间的分布（即持续荧光发射和黑暗的周期）在一个前所未有的大动态范围（10(9)）的概率密度测量，在10(5)的时间尺度范围内tau（off）的非指数行为。与此形成鲜明对比的是，所有量子点中的这些相同的tau（off）分布在这10(9)倍动态范围内通过简单的逆幂律以非常简单的方式描述，即P（tau(off)）与1/tau(off)（1 + alpha）成正比。这种逆幂律行为是分布式动力学的明确标志，例如预测(i)陷阱深度的指数分布或（ii）量子点核心/界面状态之间的隧道距离分布。这对以往所有半导体量子点荧光间歇性的研究具有重要的统计意义，并可能对其他系统（如单聚合物分子）具有更广泛的意义。(C) 2000年美国物理研究所。[s0021 - 9606(00) 01007 - 2]。
Single molecule confocal microscopy is used to study fluorescence intermittency of individual ZnS overcoated CdSe quantum dots (QDs) excited at 488 nm. The confocal apparatus permits the distribution of "on'' and "off'' times (i.e., periods of sustained fluorescence emission and darkness) to be measured over an unprecedentedly large dynamic range (10(9)) of probability densities, with nonexponential behavior in tau(off) over a 10(5) range in time scales. In dramatic contrast, these same tau(off) distributions in all QDs are described with remarkable simplicity over this 10(9)-fold dynamic range by a simple inverse power law, i.e., P(tau(off)) proportional to 1/tau(off)(1 + alpha). Such inverse power law behavior is a clear signature of distributed kinetics, such as predicted for (i) an exponential distribution of trap depths or (ii) a distribution of tunneling distances between QD core/interface states. This has important statistical implications for all previous studies of fluorescence intermittency in semiconductor QDs and may have broader implications for other systems such as single polymer molecules. (C) 2000 American Institute of Physics. [S0021-9606(00)01007-2].