Gladkikh V S, Burshtein A I
Weizmann Institute of Science, Rehovot 76100, Israel.
J Chem Phys. 2007 Jan 7;126(1):014506. doi: 10.1063/1.2423027.
The kinetic constants of rhodamine 3B quenching by N,N-dimethyl aniline were extracted from the very beginning of the quenching kinetics, recently studied in a few solvents of different viscosities. They were well fitted with the conventional kinetic constant definition, provided the radial distribution function of simple liquids was ascribed to the reactant pair distribution and the contact electron transfer rate was different in all the cases. This difference was attributed to the chemical anisotropy averaging by the rotation of reactants, which is the faster in solvents of lower viscosity. With the proper choice of a space dependent encounter diffusion, the whole quenching kinetics was well fitted with an encounter theory, using the Marcus [J. Chem. Phys. 24, 966 (1956); 43, 679 (1965)] transfer rate instead of the contact Collins-Kimball [J. Colloid. Sci. 4, 425 (1949)] approximation. Not only the beginning and middle part of the quenching were equally well fitted, but the long time (Markovian) rate constant was also found to be the same as previously obtained. Moreover, the concentration dependencies of the fluorescence quantum yield and the Stern-Volmer constant were specified and await their experimental verification.
罗丹明3B被N，N - 二甲基苯胺猝灭的动力学常数是从猝灭动力学的最初阶段提取的，最近在几种不同粘度的溶剂中进行了研究。只要将简单液体的径向分布函数归因于反应物对分布，并且在所有情况下接触电子转移速率不同，它们就与传统的动力学常数定义拟合得很好。这种差异归因于反应物旋转引起的化学各向异性平均化，在较低粘度的溶剂中这种平均化更快。通过适当选择与空间相关的遭遇扩散，整个猝灭动力学可以很好地用遭遇理论拟合，使用马库斯[《化学物理杂志》24, 966 (1956); 43, 679 (1965)]转移速率而不是接触式柯林斯 - 金博尔[《胶体科学杂志》4, 425 (1949)]近似值。不仅猝灭的开始和中间部分拟合得同样好，而且还发现长时间（马尔可夫）速率常数与之前得到的相同。此外，还确定了荧光量子产率和斯特恩 - 沃尔默常数的浓度依赖性，有待实验验证。
