Picosecond time-resolved energy transfer in Porphyridium cruentum. Part II. In the isolated light harvesting complex (phycobilisomes).
Picosecond time-resolved energy transfer in Porphyridium cruentum. Part II. In the isolated light harvesting complex (phycobilisomes).
复制标题
紫球藻中的皮秒时间分辨能量转移。
DOI：
10.1016/0005-2728(78)90030-0
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发表时间：
1978
期刊：
影响因子：
--
通讯作者：
C. Tredwell
中科院分区：
文献类型：
--
作者：
G.F.W. Searle;James Barber;George Porter;C. Tredwell
在皮秒时间尺度上观察到了藻胆体中藻胆蛋白之间激发能的转移。激发脉冲的光子密度已经被仔细地改变，以便控制在颜料床中诱导的激子相互作用的水平。530 nm的光脉冲主要被B-藻红蛋白吸收，并且该组分的荧光在脉冲持续时间内上升，并且显示出70 ps的平均1/e衰减时间。主要的发射带，集中在672 nm，是由于别藻蓝蛋白，是突出的，因为没有能量转移到叶绿素。能量从B-藻红蛋白通过R-藻蓝蛋白转移到这种色素产生120 ps的荧光最大值的上升时间。在低光子密度（1013 photons· cm−2）的激发脉冲下，别藻蓝蛋白的荧光寿命约为4 ns，但在较高光子密度下，荧光寿命降低到约2 ns。别藻蓝蛋白荧光的相对量子产率在1013- 1016 photons· cm−2的激光脉冲强度范围内几乎下降了10倍。激子-激子湮灭导致的荧光猝灭仅在别藻蓝蛋白中观察到，并且可能是该色素中单个激子的长寿命的结果。
The transfer of excitation energy between phycobiliproteins in isolated phycobilisomes has been observed on a picosecond time scale. The photon density of the excitation pulse has been carefully varied so as to control the level of exciton interactions induced in the pigment bed. The 530 nm light pulse is absorbed predominantly by B-phycoerythrin, and the fluorescence of this component rises within the pulse duration and shows a mean 1/e decay time of 70 ps. The main emission band, centred at 672 nm, is due to allophycocyanin and is prominent because of the absence of energy transfer to chlorophyll. Energy transfer to this pigment from B-phycoerythrin via R-phycocyanin produces a risetime of 120 ps to the fluorescence maximum. The lifetime of the allophycocyanin fluorescence is found to be about 4 ns using excitation pulses of low photon densities (1013photons · cm−2), but decreases to about 2 ns at higher photon densities. The relative quantum yield of the allophycocyanin fluorescence decreases almost 10 fold over the range of laser pulse intensities, 1013–1016photons · cm−2. Fluorescence quenching by exciton-exciton annihilation is only observed in allophycocyanin and could be a consequence of the long lifetime of the single exciton in this pigment.