Optical and dynamic properties of water-soluble highly luminescent CdTe quantum dots.
Optical and dynamic properties of water-soluble highly luminescent CdTe quantum dots.
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DOI：
10.1021/jp074603
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发表时间：
2007-10
期刊：
影响因子：
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通讯作者：
A. Mandal;J. Nakayama;N. Tamai;V. Biju;M. Isikawa
中科院分区：
文献类型：
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作者：
A. Mandal;J. Nakayama;N. Tamai;V. Biju;M. Isikawa
以巯基乙酸（HS-CH 2COOH，TGA）为稳定剂，在水溶液中合成了CdTe量子点。利用单分子光学显微镜研究了CdTe量子点在PVA和海藻糖中的“开”和“关”发光闪烁现象，发现单个量子点的闪烁与量子点表面吸附的水分子的相互作用有关。“关”时间，相邻的“开”状态之间的间隔，基本上不受激发强度增加的影响。无论量子点的激发强度和水环境如何，每个量子点的“关闭”时间分布都表现出类似的幂律行为。在“开”时间分布的情况下，在较长的时间尺度上观察到具有指数截止尾的幂律行为。时间曲线表明，“开”时间与激发强度成反比;“开”时间的持续时间随着激发强度的增加而变短。相对于PVA，在海藻糖中观察到“开启”时间持续时间增加。当用海藻糖代替PVA时，我们得到了幂律指数的明显降低。这些观察结果表明，发光闪烁统计的水溶性单CdTe量子点是显着依赖于水环境，这是解释量子点的表面陷阱态的钝化。
CdTe quantum dots (QDs) were synthesized in aqueous solution using thioglycolic acid (HS-CH2COOH, TGA) as a stabilizer. The phenomenon of "on" and "off" luminescence intermittency (blinking) of CdTe QDs in PVA and trehalose was investigated by single-molecule optical microscopy, and we identified that the intermittencies of single QDs were correlated with the interaction of water molecules absorbed on the QD surface. The "off" times, the interval between adjacent "on" states, remained essentially unaffected with an increase in excitation intensity. Every QD showed a similar power law behavior for the "off" time distribution regardless of the excitation intensity and aqueous environment of the QDs. In the case of "on" time distribution, power law behavior with an exponential cutoff tail is observed at longer time scales. The time traces indicated that the "on" time was inversely proportional to the excitation intensity; the duration of "on" time became shorter with increasing excitation intensity. An increase in the duration of "on" time was observed in trehalose with respect to that in PVA. We obtained a clear decrease in the power law exponent when PVA was replaced with trehalose. These observations indicate that the luminescence blinking statistics of water-soluble single CdTe QDs is significantly dependent on the aqueous environment, which is interpreted in terms of passivation of the surface trap states of QDs.