假根羽藻外周天线内能量传递的飞秒光谱研究(英文)

Study on Energy Transfer in LHC Ⅱ of Bryopsis Corticulans by Femtosecond Spectra

在时间相关单光子技术的基础上,对假根羽藻外周天线内叶绿素分子间的能量传递进行研究.采用瞬态吸收与荧光发射谱识别样品内的具有特征光谱组分的分子,得到在叶绿素分子的Q带区主要存在以下六个特征分子Chlb630,Chlb642,Chla665523,Chla666674,Chla667765,680,Chla668823.在630nm的飞秒脉冲光的激发下,通过对不同特征发射峰出的荧光动力学进行解析得到1)Chlb628分子所吸收的能量仅有大约20%被直接传递给其他叶绿素分子,传能时间小于150fs;2)叶绿素间大部分的能量传递发生在长于76ps的时间范围内;3)传能时间常量在几百fs以及10ps左右的间接传能可能与具有不同光谱组分特征的叶绿素分子在外周天线内的排列方式以及偶极距的取向有关;4)Chlb654,657652,Chla666664,Chla667747,680和Chla668823以荧光形势耗散能量的时间常量分别为1.41ns,1.39ns,676ps,709ps,这部分在整个能量耗散中占的比例不超过40%.

Based on the technique of Time Correlated Single Photon Counting （TCSPC）,energy transfer kinetics among chlorophylls in a monomeroic unit of major light-harvesting complex （LHC Ⅱ ） from bryopsis corriculan were studied. In the chlorophyll Q region, six characteristic Chla664 molecules marked as Chlb630 Chlb642, Chla652^653, Ch1a664^ 676,680 ,Ch1a682^683 were discriminated. Fluorescence kinetics measured in the chlorophyll Q region was excited by pulsed light of 630nm （70 fs）. After analyzing,results of energy transfer among chls were obtained as following：only～ 20% of the energy absorbed by Chlb630 is initially transferred directly to other Chls with time constants shorter than 150 fs. Overwhelming part of the energy transfer among chlorophylls occur with time constants longer than 76 ps. Energy transfer pathway with time constants of several hundred femotoseconds and tens of picoseconds were also obtained. The fluorescence lifetimes of Chlb652^6532 , Chla664^667, Chla675^676,680 , Chla682^683 were determined to be 1. 41 ns, 1. 39 ns, 676 ps, 709 ps respectively. The percentages of energy dissipation in the pathway of fluorescence emission are no more than 40% in the monomeric unit of LHC Ⅱ.