Xu Hao, Chmyrov Volodymyr, Widengren Jerker, Brismar Hjalmar, Fu Ying
Science for Life Laboratory, Department of Applied Physics, Royal Institute of Technology, SE-106 91 Stockholm, Sweden.
Phys Chem Chem Phys. 2015 Nov 7;17(41):27588-95. doi: 10.1039/c5cp03109e.
By narrowing the detection bandpass and increasing the signal-to-noise ratio in measuring the time-resolved fluorescence decay spectrum of colloidal CdSe-CdS/ZnS quantum dots (QDs), we show that directly after the photoexcitation, the fluorescence decay spectrum is characterized by a single exponential decay, which represents the energy relaxation of the photogenerated exciton from its initial high-energy state to the ground exciton state. The fluorescence decay spectrum of long decay time is in the form of β/t(2), where β is the radiative recombination time of the ground-state exciton and t is the decay time. Our findings provide us with a direct and quantitative link between fluorescence decay measurement data and fundamental photophysics of QD exciton, thereby leading to a novel way of applying colloidal QDs to study microscopic, physical and chemical processes in many fields including biomedicine.
通过在测量胶体CdSe-CdS/ZnS量子点（QDs）的时间分辨荧光衰减光谱时缩小检测带通并提高信噪比，我们发现光激发后直接出现的荧光衰减光谱具有单指数衰减特征，这代表了光生激子从其初始高能态到基态激子态的能量弛豫。长衰减时间的荧光衰减光谱呈β/t(2)形式，其中β是基态激子的辐射复合时间，t是衰减时间。我们的发现为荧光衰减测量数据与量子点激子的基本光物理之间提供了直接和定量的联系，从而为将胶体量子点应用于研究包括生物医学在内的许多领域中的微观、物理和化学过程开辟了一条新途径。
