Zhang X F, Xu H J, Chen D W
Institute of Photographic Chemistry, Academia Sinica, Beijing, China.
J Photochem Photobiol B. 1994 Mar;22(3):235-9. doi: 10.1016/1011-1344(93)06969-a.
The quantum yield of phthalocyanine-photosensitized generation of superoxide anion radical (O2-) was measured by the electron spin resonance (ESR) technique. From the redox potential data, it is concluded that O2- is formed by electron transfer from the singlet excited state (not triplet or ground state) of phthalocyanines (PCs) to oxygen. Since a much larger theoretical quantum yield of O2- generation (phi c) than experimental (phi m) was found, it is suggested that charge recombination processes between O2- and PCs+ occur more rapidly than O2- trapping by 5,5-dimethyl-1-pyrroline-1-oxide (DMPO). The results indicate that the use of DMPO as a spin trap is not an ideal method for measurement of the quantity of O2- formed via photosensitization.
采用电子自旋共振（ESR）技术测定了酞菁光敏化产生超氧阴离子自由基（O2-）的量子产率。根据氧化还原电位数据得出结论，O2-是通过酞菁（PCs）的单重激发态（而非三重态或基态）向氧的电子转移形成的。由于发现O2-生成的理论量子产率（φc）比实验值（φm）大得多，表明O2-与PCs+之间的电荷复合过程比5,5-二甲基-1-吡咯啉-1-氧化物（DMPO）捕获O2-的速度更快。结果表明，使用DMPO作为自旋捕获剂并非测量通过光敏化形成的O2-量的理想方法。
