Femtosecond time-resolved transient absorption spectroscopy of xanthophylls
Femtosecond time-resolved transient absorption spectroscopy of xanthophylls
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DOI：
10.1021/jp0622738
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发表时间：
2006-11-16
影响因子：
3.3
通讯作者：
Frank, Harry A.
中科院分区：
文献类型：
--
作者：
Niedzwiedzki, Dariusz M.;Sullivan, James O.;Frank, Harry A.
叶黄素是一类主要的光合色素，参与高等植物保护自身免受强光胁迫的适应机制。在目前的工作中，超快时间分辨光谱研究的所有主要的叶黄素色素从菠菜已经完成。这些分子是玉米黄质、叶黄素、紫黄质和新黄质。还研究了β-胡萝卜素。实验数据揭示了固有的光谱特性和超快动力学，包括每个颜料的S-1态寿命。结合量子力学计算的结果解决叶黄素的分子特征，控制溶液中的S* 状态的形成和衰变。研究结果提供了令人信服的证据，S* 是一个激发态的构象几何扭曲相对于基态。数据表明，S* 是通过一个分支的途径从较高的激发单重态形成的，其产量取决于关键的π-电子共轭双键的多烯系统中的β-亚离子环的存在。预计这些数据将有利于研究人员采用超快时间分辨光谱方法来研究高等植物制剂中能量转移和非光化学猝灭的机制。
Xanthophylls are a major class of photosynthetic pigments that participate in an adaptation mechanism by which higher plants protect themselves from high light stress. In the present work, an ultrafast time-resolved spectroscopic investigation of all the major xanthophyll pigments from spinach has been performed. The molecules are zeaxanthin, lutein, violaxanthin, and neoxanthin. beta-Carotene was also studied. The experimental data reveal the inherent spectral properties and ultrafast dynamics including the S-1 state lifetimes of each of the pigments. In conjunction with quantum mechanical computations the results address the molecular features of xanthophylls that control the formation and decay of the S* state in solution. The findings provide compelling evidence that S* is an excited state with a conformational geometry twisted relative to the ground state. The data indicate that S* is formed via a branched pathway from higher excited singlet states and that its yield depends critically on the presence of, beta-ionylidene rings in the polyene system of pi-electron conjugated double bonds. The data are expected to be beneficial to researchers employing ultrafast time-resolved spectroscopic methods to investigate the mechanisms of both energy transfer and nonphotochemical quenching in higher plant preparations.