Sakamoto Masanori, Cai Xichen, Fujitsuka Mamoru, Majima Tetsuro
The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan.
J Phys Chem A. 2005 Aug 11;109(31):6830-5. doi: 10.1021/jp052784e.
Dual intermolecular electron transfer (ELT) pathways from 4,4'-dimethoxybenzophenone (1) ketyl radical (1H*) in the excited state [1H*(D1)] to the ground-state 4,4'-dimethoxybenzophenone [1(S0)] were found in 2-methyltetrahydrofuran (MTHF) by observing bis(4-methoxyphenyl)methanol cation (1H+) and 4,4'-dimethoxybenzophenone radical anion (1*-) during nanosecond-picosecond two-color two-laser flash photolysis. ELT pathway I involved the two-photon ionization of 1H* following the injection of electron to the solvent. The solvated electron was quickly trapped by 1(S0) to produce 1*-. ELT pathway II was a self-quenching-like ELT from 1H*(D1) to 1(S0) to give 1H+ and 1*-. From the fluorescence quenching of 1H*(D1), the ELT rate constant was determined to be 1.0 x 10(10) M(-1) s(-1), which is close to the diffusion-controlled rate constant of MTHF. The self-quenching-like ELT mechanism was discussed on the basis of Marcus' ELT theory.
通过在纳秒-皮秒双色双激光闪光光解过程中观察双(4-甲氧基苯基)甲醇阳离子(1H+)和4,4'-二甲氧基二苯甲酮自由基阴离子(1*-)，在2-甲基四氢呋喃(MTHF)中发现了从激发态的4,4'-二甲氧基二苯甲酮(1)酮基自由基(1H*(D1))到基态4,4'-二甲氧基二苯甲酮[1(S0)]的双分子间电子转移(ELT)途径。ELT途径I涉及1H在向溶剂注入电子后发生的双光子电离。溶剂化电子迅速被1(S0)捕获以产生1-。ELT途径II是一种类似自猝灭的从1H*(D1)到1(S0)的ELT，生成1H+和1*-。根据1H*(D1)的荧光猝灭，确定ELT速率常数为1.0×10(10) M(-1) s(-1)，这接近MTHF的扩散控制速率常数。基于马库斯的ELT理论讨论了类似自猝灭的ELT机制。
