Oscillating Fluorescence in an Unstable Colloidal Dispersion of CdSe/ZnS Core/Shell Quantum Dots

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• 作者：Atsushi Komoto ; Shinya Maenosono ; and Yukio Yamaguchi
• 刊名：Langmuir
• 出版年：2004
• 出版时间：September 28, 2004
• 年：2004
• 卷：20
• 期：20
• 页码：8916 - 8923
• 全文大小：156K
• 年卷期：v.20,no.20(September 28, 2004)
• ISSN：1520-5827

文摘

Fluorescence oscillation is observed in an ensemble of colloidal CdSe/ZnS core/shell quantum dots (QDs)dispersed in nonpolar solvent under continuous irradiation. The QDs dispersed in toluene gradually aggregateand change their fluorescence intensity, even in the dark. During the aggregation, the QD/toluene suspensionis unstable, that is, overdispersed. The fluorescence oscillation is found only in this unstable state beforethe system reaches steady state. In addition, the aggregation rate is promoted by irradiation and stronglycorrelates with the oscillation amplitude. Our experimental results indicate that the dispersion instabilityplays an important role in both linear and nonlinear dynamics of the fluorescence. It is inferred from theexperimental results and previous studies that the complex time evolution of fluorescence in the QD/toluene dispersion is possibly due to adsorption and desorption of surface ligand molecules over the courseof QD aggregation.