假根羽藻外周天线LHCⅡ寡聚体的瞬态吸收光谱(英文)  

Transient Absorption Spectra of Aggregated LHC Ⅱ in Broypsis Corticulans

作　　者：贺俊芳[1] 朱长军[2] 赵小侠[1] 李院院[1] 

机构地区：[1]西安文理学院物理与机械电子工程学院,西安710065 [2]西安工程大学理学院物理系,西安710048

出　　处：《光子学报》2014年第8期215-220,共6页Acta Photonica Sinica

基　　金：The National Natural Science Foundation of China(No.60978038)

摘　　要：采用时间分辨瞬态吸收光谱技术研究了假根羽藻外周天线寡聚体的光保护机制．分别以667nm飞秒激光脉冲和白光脉冲作为泵浦光和探测光，探测光与泵浦光之间的延时范围和准确度分别为340ps和134fs．实验结果表明在泵浦光激发之后外周天线对探测光的吸收是动态变化的．对瞬态吸收光谱进行多指数拟合，并结合外周天线的荧光发射谱和激发谱进行分析，结果表明：500～600am的瞬态吸收谱主要来源于类胡萝卜素分子，外周天线寡聚体至少包含四种具有光保护作用的类胡萝卜素分子，对应的S0→Sn跃迁光谱为511nm和55413．111，522nm和541nm，530nm和563nm（对应管藻黄素），536nm和575nm；类胡萝卜素分子以两种方式参与到光保护过程中：一种是直接方式，在几皮秒范围内猝灭叶绿素三重态；另一种是间接方式，在几百皮秒范围内猝灭从叶绿素分子获得能量的单线态氧．A time resolved transient absorption spectroscopy was performed to investigate the photoprotection mechanism in light harvesting complex Ⅱ of broypsis corticulans. A 667 nm femotosenond laser and white light pulse were used as pump and probe lights. The range and accuracy of the delay line between probe and pump were 340 ps and 134 fs, respectively. The experiment results show that the absorption of the probe is dynamically changing after pump light exciting. The results of the multi-exponential fitting, fluorescence emission and excitation spectra show that the transient absorption spectra from 500 nm to 600 nm mainly originate from carotenoids and the aggregated light harvesting complex Ⅱ contains at least four types of carotenoids functioning photoprotection which have S0→Sn, transition spectral properties 511 nm and 554 nm, 522 nm and 541 nm, 530 nm and 563 nm （corresponding to siphonaxanthin）, 536 nm and 575 nm. Carotenoids play the photoprotection role not only in a direct manner by quenching the triplet state of chlorophyll a in several picoseconds, but also in an indirect manner by quenching the singlet state of oxygen in several hundreds of picoseconds.

关 键 词：瞬态吸收光谱 光合作用 泵浦探测 外周天线 光保护 类胡萝卜素 叶绿素 单线态氧 

分 类 号：Q631[生物学—生物物理学] Q632