Physics Department E11, Technical University Munich, Munich, Germany.
J Biophotonics. 2011 Mar;4(3):178-83. doi: 10.1002/jbio.201000099. Epub 2010 Oct 29.
The photodetachment of Br(-), I(-) and OH(-) in aqueous solution is studied by 2- and 3-pulse femtosecond spectroscopy. The UV excitation leads to fast electron separation followed by formation of a donor-electron pairs. An additional repump pulse is used for secondary excitation of the intermediates. The 3-pulse technique allows distinguishing the pair-intermediate from the fully separated electron. Using this method we observe a novel geminate recombination channel of .OH with adjacent hydrated electrons. The process leads to an ultrafast quenching (0.7 ps) of almost half the initial number of radicals. The phenomenon is not observed in Br(-) and I(-). Our results demonstrate the potential of the 3-pulse spectroscopy to elucidate the mechanism of ultrafast ET reactions. Photodetachment of aqueous anions studied by two- and three pulse spectroscopy.
水溶液中 Br(-)、I(-) 和 OH(-) 的光离解通过 2 脉冲和 3 脉冲飞秒光谱进行研究。紫外激发导致快速电子分离，随后形成施主-电子对。使用附加的再泵浦脉冲对中间体进行二次激发。3 脉冲技术可将电子对中间体与完全分离的电子区分开来。使用这种方法，我们观察到.OH 与相邻水合电子的新型成对复合通道。该过程导致初始自由基数量的近一半发生超快猝灭（0.7 ps）。该现象在 Br(-) 和 I(-) 中未观察到。我们的结果表明，3 脉冲光谱法具有阐明超快 ET 反应机制的潜力。通过两脉冲和三脉冲光谱研究水溶液中的阴离子光离解。
