在逐步双色双激光辐照过程中通过更高的三重激发态进行分子内三重态能量转移。

Intramolecular triplet energy transfer via higher triplet excited state during stepwise two-color two-laser irradiation.

作者信息

Oseki Yosuke, Fujitsuka Mamoru, Sakamoto Masanori, Majima Tetsuro

机构信息

The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan.

出版信息

J Phys Chem A. 2007 Oct 4;111(39):9781-8. doi: 10.1021/jp074062o. Epub 2007 Sep 7.

DOI:10.1021/jp074062o

PMID:17824596

Abstract

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.

摘要

我们在双色双激光闪光光解（2-LFP）过程中，研究了由芘（Py）、联苯（Ph2）和双邻苯二甲酰亚胺噻吩（ImT）组成的分子阵列（Py-Ph2）2-ImT中的能量转移过程。由于最低单重激发态的Py向ImT的高效单重态能量转移，随后ImT发生系间窜越，第一次激光照射主要产生处于最低三重激发态（ImT(T1)）的ImT。用第二次激光照射将ImT(T1)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（TET）过程经Ph2迅速转移到Py。纳秒-皮秒2-LFP表明Py(T1)能高效产生。在第二次激光照射后几十微秒内观察到从Py(T1)到ImT的反向TET。从Py(T1)到ImT的估计分子内TET速率低至3.1×104 s-1。因此，在2-LFP过程中选择性地高效产生了长寿命的Py(T1)。