Lambert C, Moos M, Schmiedel A, Holzapfel M, Schäfer J, Kess M, Engel V
Institute of Organic Chemistry, University of Würzburg, Am Hubland, 97074 Würzburg, Germany.
Phys Chem Chem Phys. 2016 Jul 28;18(28):19405-11. doi: 10.1039/c6cp03053j. Epub 2016 Jul 4.
The rate of thermally induced electron transfer in organic mixed valence compounds has thoroughly been investigated by e.g. temperature dependent ESR spectroscopy. However, almost nothing is known about the dynamics of optically induced electron transfer processes in such systems. Therefore, we investigated these processes in mixed valence compounds based on triphenylamine redox centres bridged by conjugated spacers by NIR transient absorption spectroscopy with fs-time resolution. These experiments revealed an internal conversion (IC) process to be on the order of 50-200 fs which is equivalent to the back electron transfer after optical excitation into the intervalence charge transfer band. This IC is followed by ultrafast cooling to the ground state within 1 ps. Thus, in the systems investigated optically induced electron transfer is about 3-4 orders of magnitude faster than thermally induced ET.
例如，通过温度依赖的电子自旋共振光谱法，已经对有机混合价化合物中热诱导电子转移的速率进行了深入研究。然而，对于此类体系中光诱导电子转移过程的动力学，人们几乎一无所知。因此，我们通过具有飞秒时间分辨率的近红外瞬态吸收光谱法，研究了基于由共轭间隔基桥连的三苯胺氧化还原中心的混合价化合物中的这些过程。这些实验表明，内部转换（IC）过程的时间尺度约为50 - 200飞秒，这相当于光激发进入价间电荷转移带后的反向电子转移。此IC过程之后是在1皮秒内超快冷却至基态。因此，在所研究的体系中，光诱导电子转移比热诱导电子转移快约3 - 4个数量级。
