Shapes of the electron-transfer rate vs energy gap relations in polar solutions
Shapes of the electron-transfer rate vs energy gap relations in polar solutions
复制标题
极性溶液中电子转移速率与能隙关系的形状
DOI：
10.1021/j100363a009
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发表时间：
1989
期刊：
影响因子：
--
通讯作者：
N. Mataga
中科院分区：
文献类型：
--
作者：
A. Yoshimori;T. Kakitani;Y. Enomoto;N. Mataga
考虑到经典的溶剂运动，并充分定义了电子转移的反应坐标，我们导出了一个将初态自由能曲线与能隙定律联系起来的公式。利用这个关系，我们证明了在电子极化率的作用可以忽略的情况下，能隙定律的下列对称性。电荷分离反应的能隙定律是对称的，在相当于重组能的能隙处有极大值。当溶剂极化的线性响应时，电荷复合反应和电荷移位反应的能隙定律是对称的，但当介质饱和引起的非线性响应时，它们可能是不对称的。结果表明，即使存在这些对称限制，当介质饱和效应增大时，电子转移速率与能隙关系的整体形状也会发生很大的变化。结果表明，在该理论方案下得到的结果与Rehm和Weller关于电荷分离反应的实验结果并不矛盾。通过蒙特卡罗模拟验证了在极性溶液中实现强介电常数饱和的可能性。
Taking into account the solvent motions classicallyand adequately defining the reaction coordinate for the electron transfer, we have derived a formula whichrelates the free energy curve of the initial state to the energy gap law. Using this relation, we haveproved the following symmetrical properties of the energy gap law in the case where the role of the electronicpolarizability can be neglected. The energy gap law of the charge separation reaction is symmetric with a maximum at the energy gap equivalent to the reorganization energy. The energy gap laws of the charge recombination and charge shift reactions are symmetric when a linear response of the solvent polarization applies but they can be asymmetric when a nonlinear response due to the dielectric saturationapplies. It has been demonstrated that even if these symmetric restrictions exist, the overall shape of the electron-transfer rate vs energy gap relation is greatly modified when the dielectric saturation effect is increased. It is shown that the result obtained within this theoretical scheme is not inconsistent with the experimentalresults by Rehm and Weller for the charge separation reaction. The possibilityof realizing a strong dielectric saturation in polar solutions is examined by the Monte Carlo simulation.