School of Chemistry, Norwich Research Park, University of East Anglia , Norwich NR4 7TJ, U.K.
J Phys Chem A. 2015 Jan 8;119(1):95-101. doi: 10.1021/jp511881a. Epub 2014 Dec 15.
In this work we present experimental and calculated two-dimensional electronic spectra for a 5,15-bisalkynyl porphyrin chromophore. The lowest energy electronic Qy transition couples mainly to a single 380 cm(-1) vibrational mode. The two-dimensional electronic spectra reveal diagonal and cross peaks which oscillate as a function of population time. We analyze both the amplitude and phase distribution of this main vibronic transition as a function of excitation and detection frequencies. Even though Feynman diagrams provide a good indication of where the amplitude of the oscillating components are located in the excitation-detection plane, other factors also affect this distribution. Specifically, the oscillation corresponding to each Feynman diagram is expected to have a phase that is a function of excitation and detection frequencies. Therefore, the overall phase of the experimentally observed oscillation will reflect this phase dependence. Another consequence is that the overall oscillation amplitude can show interference patterns resulting from overlapping contributions from neighboring Feynman diagrams. These observations are consistently reproduced through simulations based on third order perturbation theory coupled to a spectral density described by a Brownian oscillator model.
在这项工作中，我们展示了一个 5,15-双炔基卟啉发色团的实验和计算二维电子光谱。最低能量的电子 Qy 跃迁主要与一个 380 cm(-1) 的振动模式耦合。二维电子光谱显示了作为种群时间函数的对角和交叉峰的振荡。我们分析了作为激发和检测频率函数的主要振动跃迁的幅度和相位分布。尽管费曼图很好地表明了振幅的振荡分量在激发-检测平面中的位置，但其他因素也会影响这种分布。具体来说，每个费曼图对应的振荡预计具有一个相位，它是激发和检测频率的函数。因此，实验观察到的振荡的整体相位将反映出这种相位依赖性。另一个结果是，整体振荡幅度可以显示出由于相邻费曼图的重叠贡献而产生的干涉模式。这些观察结果通过基于三阶微扰理论的模拟得到了一致的再现，该模拟与由布朗振荡器模型描述的光谱密度耦合。
