Ultrafast dynamics of photogenerated styrylpyridinyl radical and its dimer radical cation with styrylpyridinium cation studied by femtosecond laser flash photolysis
Ultrafast dynamics of photogenerated styrylpyridinyl radical and its dimer radical cation with styrylpyridinium cation studied by femtosecond laser flash photolysis
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飞秒激光闪光光解研究光生苯乙烯吡啶自由基及其二聚体自由基阳离子与苯乙烯吡啶鎓阳离子的超快动力学
DOI：
10.1039/a806076b
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
T. Nagamura
中科院分区：
文献类型：
--
作者：
H. Kawai;T. Nagamura
通过飞秒激光闪光光解苯乙烯基吡啶鎓阳离子和四苯基硼酸根阴离子之间的离子对电荷转移复合物，在室温下在极性较小的溶剂中研究了超快光诱导电子转移反应和二聚体自由基阳离子的形成。除了苯乙烯基吡啶基自由基引起的可见光吸收之外，在近红外区域还观察到由于光生苯乙烯基吡啶基自由基和苯乙烯基吡啶鎓阳离子之间的电子相互作用而产生的电荷共振吸收带（CR带）。自由基和 CR 带的瞬时吸收在不到 1 ps 的时间内表现出非常快速的上升，这受到闪光光解系统的时间分辨率的限制。在光激发之前没有观察到苯乙烯基吡啶鎓阳离子的相互作用。这些结果强烈表明苯乙烯吡啶鎓离子与其还原形式之间的电子相互作用在光诱导电子转移后没有立即发生扩散过程。从衰变动力学来看，发现二聚体自由基阳离子显示出比自由基本身更快的反向电子转移。
Ultrafast photoinduced electron transfer reaction and dimer radical cation formation have been studied at room temperature in less polar solvents by femtosecond laser flash photolysis of ion-pair charge-transfer complexes between a styrylpyridinium cation and a tetraphenylborate anion. In addition to the visible absorption due to the styrylpyridinyl radicals, the charge resonance absorption band (CR band) due to the electronic interaction between the photogenerated styrylpyridinyl radical and the styrylpyridinium cation was observed in the near infrared region. Transient absorptions of both radicals and the CR band showed very rapid rise in less than 1 ps, which was limited by the time resolution of the flash photolysis system. No interaction of styrylpyridinium cations was observed before photoexcitation. These results strongly suggested that the electronic interaction between the styrylpyridinium ion and its reduced form occurred without a diffusion process immediately after photoinduced electron transfer. From the decay dynamics, the dimer radical cation was found to show a faster back electron transfer than the radical itself.