Lukzen N N, Pedersen J B, Burshtein A I
International Tomography Center, Novosibirsk 630090, Russia.
J Phys Chem A. 2005 Dec 29;109(51):11914-26. doi: 10.1021/jp053539y.
The double-channel recombination and separation of the photochemically created singlet radical pair is investigated, taking into account the spin conversion in a zero magnetic field and the arbitrary initial distance between the radicals. The quantum yields of the singlet and triplet products and the free radicals production are found analytically, assuming that the recombination of the diffusing radicals occurs at contact. All the yields are related to the singlet and triplet populations of the recombining radical pair, subjected to spin conversion and contact exchange interaction. The general analytical expressions for the quantum yields are specified for the particular limits of the weak and strong exchange. They are greatly simplified in the case of polar solvents, especially at the contact start. A close similarity is obtained with the results of a previously developed incoherent model of spin conversion, provided that the conversion rate is appropriately related to the hyperfine coupling constant.
研究了光化学产生的单线态自由基对的双通道复合与分离，考虑了零磁场中的自旋转换以及自由基之间的任意初始距离。假设扩散自由基在接触时发生复合，通过解析方法得出了单线态和三线态产物的量子产率以及自由基生成量。所有产率都与复合自由基对的单线态和三线态布居有关，该布居受到自旋转换和接触交换相互作用的影响。针对弱交换和强交换的特定极限，给出了量子产率的一般解析表达式。在极性溶剂的情况下，尤其是在接触起始时，这些表达式会大大简化。如果转换速率与超精细耦合常数适当地相关，则与先前开发的自旋转换非相干模型的结果非常相似。
