Investigations of Energy Migration in an Organic Dendrimer Macromolecule for Sensory Signal Amplification
Investigations of Energy Migration in an Organic Dendrimer Macromolecule for Sensory Signal Amplification
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DOI：
10.1021/jp8112123
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发表时间：
2009-04-23
影响因子：
2.9
通讯作者：
Goodson, Theodore, III
中科院分区：
文献类型：
--
作者：
Guo, Meng;Varnavski, Oleg;Goodson, Theodore, III
利用非线性光学和时间分辨光谱的研究结果，对含能材料的大分子激子离域长度和荧光传感问题进行了研究和建模。利用双光子和三光子吸收技术研究了有机树枝状大分子对TNT的荧光猝灭效应。检查该组树枝状聚合物的Stem-Volmer图，并获得树枝状聚合物G4的大猝灭常数（1400 M-1）。发现猝灭常数随树枝状大分子代数的增加而增加。通过飞秒荧光上转换激发子动力学研究了树枝状聚合物体系灵敏度增强的机理。荧光寿命的测量结果表明，多组分松弛，不同的树枝状大分子代。荧光各向异性衰减测量被用来探测这些树枝状聚合物系统中的激子迁移长度，并且对于大结构，激发迁移区域覆盖类似于20个单位。所有这些结果被用于一个模型，该模型描述了激子的本地化长度与荧光猝灭强度。时间分辨技术的使用允许在有机大分子中的感觉放大的机制的更接近和更详细的描述。
The issue of macromolecular exciton delocalization length and fluorescence sensing of energetic materials is investigated and modeled from results of nonlinear optical and time-resolved spectroscopy. By using two- and three-photon absorption techniques the fluorescence quenching effects of an organic dendrimer for sensing TNT were carried out. The Stem-Volmer plots for the set of dendrimers were examined and a large quenching constant for the dendrimer G4 was obtained (1400 M-1). The quenching constant was found to increase with the dendrimer generation number. The mechanism for the enhanced sensitivity of the dendrimer system was examined by probing the exciton dynamics with femtosecond fluorescence up-conversion. Fluorescence lifetime measurements revealed a multicomponent relaxation that varied with dendrimer generation. Fluorescence anisotropy decay measurements were used to probe the exciton migration length in these dendrimer systems and for the large structure the excitation migration area covers similar to 20 units. All of these results were used in a model that describes the exciton localization length with the fluorescence quenching strength. The use of time-resolved techniques allows for a closer and more detailed description of the mechanism of sensory amplification in organic macromolecules.