Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, People's Republic of China.
J Phys Chem B. 2011 May 19;115(19):6265-71. doi: 10.1021/jp200455b. Epub 2011 Apr 14.
Photoinduced electron transfer based fluorescence correlation spectroscopy (PET-FCS) is a powerful tool to study biomolecular processes. However, some questions remain as to how to correctly interpret the PET-FCS data. In this work, we studied the PET process between tetramethylrhodamine and guanosine by means of femtosecond transient absorption spectroscopy. We derived that the charge separation rate is 4.1 × 10(9) s(-1) and the charge recombination rate is 5.2 × 10(10) s(-1) for the current system, supporting the three-state model and the interpretation on PET-FCS experiments given by Qu et al. (J. Phys Chem. B, 2010, 114, 8235). At the limit that both the charge separation and recombination rates are much faster than the process that PET-FCS reveals, the three-state model can be simplified to an equivalent two-state model with a dark state whose brightness is nonzero. We propose ways to obtain the brightness of the dark state with additional experiments, which is necessary for a PET-FCS study.
基于光诱导电子转移的荧光相关光谱（PET-FCS）是研究生物分子过程的有力工具。然而，对于如何正确解释 PET-FCS 数据，仍存在一些问题。在这项工作中，我们通过飞秒瞬态吸收光谱研究了四甲基罗丹明和鸟苷之间的光诱导电子转移过程。我们得出，对于当前的体系，电荷分离速率为 4.1×10(9)s(-1)，电荷复合速率为 5.2×10(10)s(-1)，支持 Qu 等人提出的三态模型以及对 PET-FCS 实验的解释（J. Phys. Chem. B, 2010, 114, 8235）。在电荷分离和复合速率远快于 PET-FCS 揭示的过程的极限下，三态模型可以简化为一个具有非零暗态的等效两态模型。我们提出了通过附加实验获得暗态亮度的方法，这对于 PET-FCS 研究是必要的。
