【摘要】 采用飞秒时间分辨荧光光谱学对PSⅡ颗粒复合物在 83K ,16 0K ,2 73K下进行研究 ,实验表明随温度升高 ,光谱加宽 并且发现在PSⅡ颗粒复合物中至少存在以下几种特征Chl分子 :Chlb6 406 39,Chlb6 456 40 ,Chla6 6 36 6 0 ,Chla6 6 86 6 7,Chla6 76 6 73,Chla6 816 80 ,Chla6 826 80 /6 81,Chla6 88/6 896 84 ,6 85,Chla6 986 88 在不同的温度下 ,参与能量传递的色素分子传能途径各不相同 ,但都有一个共同点 :在到达反应中心之前能量传递高效进行 ,绝大多数能量传递到了反应中心 ,而在 6 80nm之后的波段 ,能量损耗明显增大 ,这是由于电子传能受阻 ,能量绝大多数以荧光形式耗散 对荧光衰减曲线进行时间拟合 ,得到四组时间常数 :30～ 4 0ps ,2 6 0ps ,5 5 0～ 6 70ps ,1～ 8ns 几个ns的长寿命组分 ,反映了两个能量传递过程 ,即与基对态P6 80 + pheo- ,以及能量传递过程中Chla分子由激发态辐射荧光衰退到基态以辐射荧光形式丢失能量的过程有关 5 5 0～ 6 70ps的时间组分 ,反映的是部分电荷重组的过程 2 6 0ps的组分只在 83K出现 ,应归于LHCⅡ中的Car分子经中间传递体传能到Chlb 6 39分子后继续将能量传递到反应中心P6 80的时间 30～ 4 0ps的时间组分为LHCⅡ中的Chl分子吸收光能后通过一系列中间体将能量传更多还原

【Abstract】 In order to understanding the diversity of energy transfer in PSⅡ at different temperatures, PSⅡ particle complex purified from spinach was investigated with femtosecond time-resolved fluorescence spectroscopy in the case of excitation 507 nm at 83 K, 160 K, 273 K. The data were analyzed by Gauss analysis and fluorescence decay time-fitting. Some results were achieved. ①Increase of the temperature results in a broadening of the fluorescence emission spectra due to the temperature-dependent expressions for non-radiative transitions between two electronic states. ②There are at least several characteristic Chl molecules exist in PSⅡ particle complex,i.e. Chl b 640 639,Chl b 645 640,Chl a 663 660,Chl a 668 667,Chl a 676 673,Chl a 681 680,Chl a 682 680/681,Chl a 688/689 684,685,Chl a 698 688 (Chl a/b e a:a represents the peak of absorption ,e represents the peak of emission). ③Though the pathways of energy transfer are variable at different temperatures, there is a common property at all temperature: The energy transfer from pigments with absorption at short wavelength to reaction center pigments P680 is efficient, but from P680 to other pigments, the energy-loss becomes larger as a result of abruption of electron transfer. ④Four time constants 30～40 ps, 260 ps, 550～670 ps and 1～8 ns are obtained by the method of fitting the fluorescence decay curves. The long-life time constant of 1～8 ns is related to radical pair state P680 +pheo - and the process of excited state decaying to ground state. A component in the range of 550～670 ps refers to partial charge recombination process. 260 ps appears only at 83 K, is attributed to the progress of energy transfer from Car in LHCⅡ to Chl b 639 molecule and then to P680 by a series of intermediates. The shortest lifetime of 30～40 ps is ascribed to an energy transfer from Chl in LHCⅡ to Chl a 680/681 molecule in reaction center by intermediates.更多还原