Schweighöfer Felix, Dworak Lars, Braun Markus, Zastrow Marc, Wahl Jan, Burghardt Irene, Rück-Braun Karola, Wachtveitl Josef
Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, Max-von-Laue Str. 7, D 60438 Frankfurt/M., Germany.
TU-Berlin, Strasse des 17. Juni 135, D 10623 Berlin, Germany.
Sci Rep. 2015 Mar 23;5:9368. doi: 10.1038/srep09368.
The ring opening of a dithienylethene photoswitch incorporated in a bridged boron-dipyrromethene - dithienylethene molecular dyad was investigated with ultrafast spectroscopy. Coherent vibrations in the electronic ground state of the boron-dipyrromethene are triggered after selective photoexcitation of the closed dithienylethene indicating vibrational coupling although the two moieties are electronically isolated. A distribution of short-lived modes and a long-lived mode at 143 cm(-1) are observed. Analysis of the theoretical frequency spectrum indicates two modes at 97 cm(-1) and 147 cm(-1) which strongly modulate the electronic transition energy. Both modes exhibit a characteristic displacement of the bridge suggesting that the mechanical momentum of the initial geometry change after photoexcitation of the dithienylethene is transduced to the boron-dipyrromethene. The relaxation to the dithienylethene electronic ground state is accompanied by significant heat dissipation into the surrounding medium. In the investigated dyad, the boron-dipyrromethene acts as probe for the ultrafast photophysical processes in the dithienylethene.
利用超快光谱研究了包含在桥连硼二吡咯亚甲基 - 二噻吩乙烯分子二元体系中的二噻吩乙烯光开关的开环过程。在封闭的二噻吩乙烯选择性光激发后，硼二吡咯亚甲基电子基态中的相干振动被触发，这表明尽管两个部分在电子上是隔离的，但存在振动耦合。观察到了在143 cm⁻¹处的短寿命模式和长寿命模式的分布。理论频谱分析表明，在97 cm⁻¹和147 cm⁻¹处有两种模式强烈调制电子跃迁能量。这两种模式都表现出桥的特征性位移，表明二噻吩乙烯光激发后初始几何形状变化的机械动量被传递到了硼二吡咯亚甲基。向二噻吩乙烯电子基态的弛豫伴随着大量热量耗散到周围介质中。在所研究的二元体系中，硼二吡咯亚甲基充当了二噻吩乙烯中超快光物理过程的探针。
