Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA.
Phys Rev Lett. 2009 Nov 13;103(20):207402. doi: 10.1103/PhysRevLett.103.207402. Epub 2009 Nov 11.
We present a new physical model resolving a long-standing mystery of the power-law distributions of the blinking times in single colloidal quantum dot fluorescence. The model considers the nonradiative relaxation of the exciton through multiple recombination centers. Each center is allowed to switch between two quasistationary states. We point out that the conventional threshold analysis method used to extract the exponents of the distributions for the on times and off times has a serious flaw: the qualitative properties of the distributions strongly depend on the threshold value chosen for separating the on and off states. Our new model explains naturally this threshold dependence, as well as other key experimental features of the single quantum dot fluorescence trajectories, such as the power-law power spectrum (1/f noise).
我们提出了一个新的物理模型，解决了单个胶体量子点荧光中，荧光猝灭时间的幂律分布的一个长期存在的谜团。该模型考虑了激子通过多个复合中心的非辐射弛豫。每个中心都允许在两个准静态态之间切换。我们指出，用于提取分布的指数的传统阈值分析方法，对于开态和关态的分离，存在一个严重的缺陷：分布的定性特性强烈依赖于所选择的阈值。我们的新模型自然地解释了这种阈值依赖性，以及单量子点荧光轨迹的其他关键实验特征，例如幂律功率谱（1/f 噪声）。
