Intramolecular triplet energy transfer via higher triplet excited state during stepwise two-color two-laser irradiation.
Intramolecular triplet energy transfer via higher triplet excited state during stepwise two-color two-laser irradiation.
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DOI：
10.1021/jp074062o
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发表时间：
2007-09
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影响因子：
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通讯作者：
Yosuke Oseki;M. Fujitsuka;M. Sakamoto;T. Majima
中科院分区：
文献类型：
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作者：
Yosuke Oseki;M. Fujitsuka;M. Sakamoto;T. Majima
研究了芘（Py）、联苯（Ph 2）和双邻苯二甲酰亚胺噻吩（ImT）组成的分子阵列（（Py-Ph 2）2-ImT）在双色双激光闪光光解（2-LFP）过程中的能量传递过程。第一激光照射主要产生处于最低三重激发态的ImT（ImT（T1）），这是因为从处于最低单重激发态的Py到ImT的有效单重态能量转移，然后是ImT的系间穿越。通过第二激光照射，ImT（T1）被激发到更高的三重激发态（Tn）。然后，三重态能量通过两步三重态能量转移（泰特）过程通过Ph 2快速转移到Py。从纳秒-皮秒2-LFP提出了Py（T1）的有效产生。在第二次激光照射之后，观察到从Py（T1）到ImT的反向TET持续数十微秒。从Py（T1）到ImT的估计分子内泰特速率低至3.1 x 104 s-1。因此，在2-LFP期间选择性地且有效地产生长寿命的Py（T1）。
We studied the energy transfer processes in the molecular array consisting of pyrene (Py), biphenyl (Ph2), and bisphthalimidethiophene (ImT), (Py-Ph2)2-ImT, during two-color two-laser flash photolysis (2-LFP). The first laser irradiation predominantly generates ImT in the lowest triplet excited state (ImT(T1)) because of the efficient singlet energy transfer from Py in the lowest singlet excited state to ImT and, then, intersystem crossing of ImT. ImT(T1) was excited to the higher triplet excited state (Tn) with the second laser irradiation. Then, the triplet energy was rapidly transferred to Py via a two-step triplet energy transfer (TET) process through Ph2. The efficient generation of Py(T1) was suggested from the nanosecond-picosecond 2-LFP. The back-TET from Py(T1) to ImT was observed for several tens of microseconds after the second laser irradiation. The estimated intramolecular TET rate from Py(T1) to ImT was as slow as 3.1 x 104 s-1. Hence, long-lived Py(T1) was selectively and efficiently produced during the 2-LFP.