Single molecule studies of quantum dot fluorescence intermittency: evidence for both dark and light-assisted blinking dynamics
Single molecule studies of quantum dot fluorescence intermittency: evidence for both dark and light-assisted blinking dynamics
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DOI：
10.1080/00268970902933820
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发表时间：
2009-01-01
影响因子：
1.7
通讯作者：
Nesbitt, David J.
中科院分区：
文献类型：
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作者：
Baker, Thomas A.;Rouge, Jessica L.;Nesbitt, David J.
本工作研究单一的CdSe量子点闪烁行为在没有照明的情况下，为了阐明长时间动力学的光激发的作用。发现QD在黑暗中从高量子产率（“开”）状态转变到低量子产率（“关”）状态的概率极低，并且基本上与从100 ms到分钟时间尺度的停留时间无关。暗通道的缺乏与许多模型一致，例如，其中“开”到“关”的闪烁归因于光辅助俄歇电离和QD的充电。另一方面，闪烁恢复统计（从“关”到“开”状态）揭示了近似的幂律依赖于停留时间，在黑暗中与非光活化和高度分布的动力学一致。最重要的是，这样的暗QD恢复比在恒定照明条件下通过先前幂律动力学研究预测的慢几个数量级，突出了（i）光激活和（ii）暗闪烁恢复途径两者的存在。此外，动力学分析表明，迄今为止，几乎所有的单CdSe量子点的研究已经进行的条件下，闪烁恢复是由光激活通道的日期占主导地位。
The present work investigates single CdSe QD blinking behaviour in the absence of illumination, in order to elucidate the role of photoexcitation on the long time dynamics. The probability of a QD transitioning in the dark from a high quantum yield ('on') state to a low quantum yield ('off') state is found to be extremely low and essentially independent of dwell time from 100 ms to minute time scales. The absence of a dark pathway is consistent with many models, for example, in which 'on' to 'off' blinking is ascribed to photo-assisted Auger ionization and charging of the QD. On the other hand, blinking recovery statistics (from 'off' to 'on' state) reveal an approximate power law dependence on dwell time, consistent with non-photoactivated and highly distributed kinetics in the dark. Most importantly, such dark QD recovery is orders of magnitude slower than predicted by previous power law kinetic studies under constant illumination conditions, highlighting the presence of both (i) light-activated and (ii) dark blinking recovery pathways. Furthermore, the kinetic analysis indicates that nearly all single CdSe QD studies to date have been performed under conditions where blinking recovery is dominated by the light-activated channel to date.