Fluorescence lifetime fluctuations of single molecules probe local density fluctuations in disordered media: a bulk approach.
Fluorescence lifetime fluctuations of single molecules probe local density fluctuations in disordered media: a bulk approach.
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单分子的荧光寿命波动探测无序介质中的局部密度波动：一种本体方法。
DOI：
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发表时间：
2005
影响因子：
4.4
通讯作者：
N. V. Hulst
中科院分区：
文献类型：
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作者：
R. Vallée;N. Tomczak;G. Vancso;L. Kuipers;N. V. Hulst
我们通过监测嵌入的单个荧光团的动力学来研究聚合物在玻璃态下的纳米级迁移率。最近，我们报道了荧光寿命波动，它反映了聚合物在单分子探针周围的链段重排动力学。在这里，我们集中讨论这些荧光寿命波动的性质。首先讨论了猝灭和分子构象变化的潜在作用。接下来，我们集中于辐射态密度对镶嵌在聚合物中的单个染料分子自发辐射的影响。为此，我们提出了一种将有效介质理论与胞洞模型相联系的理论，该模型起源于Simha-Somcynsky自由体积理论。导出的自由体积分布与荧光寿命之间的关系使人们可以直接从实验数据中确定参与局部重排的链段数目。给出了两种不同聚合物随温度变化的结果。
We investigated the nanometer scale mobility of polymers in the glassy state by monitoring the dynamics of embedded single fluorophores. Recently we reported on fluorescence lifetime fluctuations which reflect the segmental rearrangement dynamics of the polymer in the surroundings of the single molecule probe. Here we focus on the nature of these fluorescence lifetime fluctuations. First the potential role of quenching and molecular conformational changes is discussed. Next we concentrate on the influence of the radiative density of states on the spontaneous emission of individual dye molecules embedded in a polymer. To this end we present a theory connecting the effective-medium theory to a cell-hole model, originating from the Simha-Somcynsky free-volume theory. The relation between the derived distributions of free volume and fluorescence lifetime allows one to determine the number of segments involved in the local rearrangement directly from experimental data. Results for two different polymers as a function of temperature are presented.