Gepshtein Rinat, Huppert Dan, Agmon Noam
Raymond and Beverly Sackler Faculty of Exact Sciences, School of Chemistry, Tel Aviv University, Tel Aviv 69978, Israel.
J Phys Chem B. 2006 Mar 9;110(9):4434-42. doi: 10.1021/jp0540095.
We report time-resolved fluorescence data for the anion of p-hydroxybenzylidene dimethylimidazolinone (p-HBDI), a model chromophore of the green fluorescence protein, in viscous glycerol-water mixtures over a range of temperatures, T. The markedly nonexponential decay of the excited electronic state is interpreted with the aid of an inhomogeneous model possessing a Gaussian coordinate-dependent sink term. A nonlinear least-squares fitting routine enables us to achieve quantitative fits by adjusting a single activation parameter, which is found to depend linearly on 1/T. We derive an analytic expression for the absolute quantum yield, which is compared with the integrated steady-state fluorescence spectra. The microscopic origins of the model are discussed in terms of two-dimensional dynamics, coupling the phenyl-ring rotation to a swinging mode that brings this flexible molecule to the proximity of a conical intersection on its multidimensional potential energy surface.
我们报告了对羟基苄叉二甲基咪唑啉酮（p-HBDI，绿色荧光蛋白的一种模型发色团）阴离子在一系列温度T下于粘性甘油-水混合物中的时间分辨荧光数据。借助具有高斯坐标依赖汇项的非均匀模型对激发电子态明显的非指数衰减进行了解释。通过调整单个活化参数，一种非线性最小二乘拟合程序使我们能够实现定量拟合，发现该参数与1/T呈线性依赖关系。我们推导了绝对量子产率的解析表达式，并将其与积分稳态荧光光谱进行了比较。根据二维动力学讨论了该模型的微观起源，将苯环旋转与一种摆动模式相耦合，这种摆动模式使这个柔性分子在其多维势能面上接近一个锥形交叉点。
