Mackowski Sebastian, Wörmke Stephan, Ehrl Moritz, Bräuchle Christoph
Department of Chemistry and Biochemistry, Ludwig-Maximilian-University Munich, Munich, Germany.
J Fluoresc. 2008 May-Jul;18(3-4):625-31. doi: 10.1007/s10895-008-0326-1. Epub 2008 Feb 16.
We report on studies of the influence of the matrix on the spectral dynamics of the zero-phonon-line (ZPL) emission by means of single molecule spectroscopy at low temperature. The host-guest system combinations consist of terrylenediimide (TDI) molecules embedded in four n-alkane matrixes of hexane, heptane, pentadecane, and hexadecane. Excitations into the broad vibronic absorption band and spectrally dispersed detection allows us to monitor fluorescence of single TDI molecules as a function of time. In the case of long-chain n-alkanes (pentadecane and hexadecane), the ZPL line is quite stable, showing spectral jumps of moderate frequency of less than 10 cm(-1) with an average time between the jumps of 10 s. In a clear contrast, the spectral dynamics of TDI molecules embedded within the short-length n-alkane matrixes (heptane and hexane) feature much more frequent spectral jumps that occur on a broader energy scale. The results suggest that matrixes composed of short-chain molecules are more susceptible to translations and/or rotations, which influence the fluorescence of single guest chromophores.
我们报告了在低温下通过单分子光谱研究基质对零声子线（ZPL）发射光谱动力学的影响。主客体系统组合由嵌入己烷、庚烷、十五烷和十六烷四种正构烷烃基质中的苝二酰亚胺（TDI）分子组成。对宽振动吸收带的激发和光谱分散检测使我们能够监测单个TDI分子的荧光随时间的变化。在长链正构烷烃（十五烷和十六烷）的情况下，ZPL线相当稳定，显示出频率适中的光谱跳跃，小于10 cm(-1)，跳跃之间的平均时间为10 s。与之形成鲜明对比的是，嵌入短链正构烷烃基质（庚烷和己烷）中的TDI分子的光谱动力学具有更频繁的光谱跳跃，这些跳跃发生在更宽的能量范围内。结果表明，由短链分子组成的基质更容易发生平移和/或旋转，这会影响单个客体发色团的荧光。
