Fron Eduard, Schweitzer Gerd, Jacob Josemon, Van Vooren Antoine, Beljonne David, Müllen Klaus, Hofkens Johan, Van der Auweraer Mark, De Schryver Frans C
Department of Chemistry, Katholieke Universiteit Leuven, Belgium.
Chemphyschem. 2007 Jun 25;8(9):1386-93. doi: 10.1002/cphc.200700136.
The excited-state properties of two peryleneimide chromophore end-capped pentaphenylene compounds were investigated in detail using femtosecond transient absorption and single-photon timing experiments. Singlet-singlet annihilation was found to promote one chromophore into a higher excited state and results in the formation of an ultra-short-living intermediate charge-transfer (CT) state in the S(n)-S(1) deactivation pathway. In low-polarity solvents, this CT state is found to be energetically higher than the first excited state and thus cannot be populated via one-photon excitation. The observed CT state decays with a time constant of about 1 ps to form the lowest singlet excited state. These results demonstrate the potential use of the singlet-singlet annihilation as a novel tool in studying reactions occurring in states that are energetically above the S(1).
利用飞秒瞬态吸收和单光子计时实验，详细研究了两种苝酰亚胺发色团封端的并五苯化合物的激发态性质。发现单重态-单重态湮灭可将一个发色团提升至更高激发态，并在S(n)-S(1)失活途径中导致形成超短寿命的中间电荷转移(CT)态。在低极性溶剂中，发现该CT态在能量上高于第一激发态，因此不能通过单光子激发来填充。观察到的CT态以约1 ps的时间常数衰减，形成最低单重激发态。这些结果证明了单重态-单重态湮灭作为一种新型工具在研究能量高于S(1)的态中发生的反应方面的潜在用途。
