The formation of triplet chlorophyll and carotenoid by radical pair recombination have been observed in the reaction centers of photosystems of bacteria and higher plants. This is an important process for the photoprotection of the reaction centers, for the dissipation of excessive energy by non-radiative decay of carotenoid triplet. Triplet generation by the same mechanism in an artificial system has rarely been observed, only a few cases were reported in donor-acceptor triad supermolecules. This is probably the first time report of the simulation of the generation of triplet by back electron transfer using dye-sensitized TiO2 solar cell reaction. Triplet states have been observed in all-trans-retinoic acid sensitized TiO2 colloid during the recombination of the trapped electron with the retinoic acid radical cation after photoexcitation. The intermediates were characterized by ns time-resolved spectroscopy.
太阳能电池反应模拟光合系统反应中心电荷复合形成三线态分子的过程
翁羽翔* 徐景周 潘洁 林开利 汪力 杨国桢
（中国科学院物理研究所，北京100080）
摘要：光合系统反应中心普遍存在电荷复合反应形成三线态分子的过程,并通过所形成的三线态β-胡萝卜素将剩余的能量经无辐射通道耗散给环境,实现光合系统的光保护功能.这一过程在人工合成系统中十分罕见,见诸报道的仅有少数由给体-受体组成的超分子体系.首次报道应用染料敏化TiO2胶体颗粒的人工太阳能电池反应,模拟光合系统三线态分子的形成过程,成功地观测到了视黄酸自由基正离子与TiO2表面束缚电子复合而形成的三线态视黄酸分子,并对其光谱和动力学过程进行了纳秒时间分辨光谱表征.
关键词： 光合反应；三线态；TiO2；视黄酸；瞬态吸收光谱
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