Emission intensity dependence and single-exponential behavior in single colloidal quantum dot fluorescence lifetimes
Emission intensity dependence and single-exponential behavior in single colloidal quantum dot fluorescence lifetimes
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DOI：
10.1021/jp035756
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发表时间：
2004-01-08
影响因子：
3.3
通讯作者：
Bawendi, MG
中科院分区：
文献类型：
--
作者：
Fisher, BR;Eisler, HJ;Bawendi, MG
我们目前的光致发光衰减动力学测量从单个胶体CdSe量子点。我们发现，衰变波动的时间与衰变率与时间平均发射强度。此外，通过仅选择在单个量子点发射强度接近其最大值时收集的那些光子来测量衰变产生单指数动力学。我们发现，“最大强度”衰减几乎相同的不同独立合成的样品几乎相同。单指数动力学和衰减的组合，是可重复的样品导致我们推测，这是辐射寿命的测量和量子产率的一个点附近的最大发射强度接近统一。衰变率随时间的变化及其与发射强度的相关性表明，这些强度的时间轨迹主要反映了非辐射弛豫路径的波动。
We present measurements of photoluminescence decay dynamics from single colloidal CdSe quantum dots. We find that the decays fluctuate in time with decay rates that correlate with time-averaged emission intensities. Moreover, the decays measured by selecting only those photons collected while the single quantum dot emission intensity was near its maximum yields single-exponential dynamics. We find that the "maximum-intensity" decays are nearly identical across different independently synthesized samples of nearly the same size. The combination of single-exponential kinetics and decays that are reproducible across samples leads us to speculate that it is the radiative lifetime that is measured and that the quantum yield of a single dot near its maximum emission intensity is close to unity. The variations in decay rates with time and their correlation with emission intensity indicate these intensity time trajectories primarily reflect fluctuations in nonradiative relaxation pathways.