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本文采用分立型的激子模型和Monte Carlo计算机模拟方法,对藻胆蛋白中激发态衰变进行了研究。结果表明:激子湮灭程度随激发光强和体系中色团数目的增加而增加,湮灭在光强约为10~13光子/cm~2时开始出现,到光强约为10~15—10~16光子/cm~2时达到饱和。激发态衰变曲线能否以单指数拟合不能作为湮灭存在与否的判据。湮灭程度与荧光量子产率直接相关。文献报道的所谓“安全”光强数值无普遍意义,因湮灭还与脉宽、色团的光捕获截面和光吸收系数等有关。
In this paper, discrete exciton model and Monte Carlo computer simulation methods were used to study the excited state decay in phycobiliproteins. The results show that the degree of exciton annihilation increases with the increase of excitation light intensity and the number of chromophores in the system. The annihilation begins when the light intensity is about 10 ~ 13 photons / cm ~ 2, and the light intensity is about 10 ~ 15-10 ~ 16 photons / cm ~ 2 to reach saturation. Whether the decay curve of the excited state can be fitted by a single exponential can not be used as a criterion for the existence of annihilation. The degree of annihilation is directly related to the fluorescence quantum yield. The so-called “safe” light intensity values reported in the literature are of no universal significance because annihilation is also related to the pulse width, the light capture cross-section of the chromophores and the light absorption coefficient.