The kinetics of excited-state energy migration were investigated by femtosecond transient absorption in the isolated Photosystem I-Light-Harvesting Complex I (PSI-LHCI) supercomplex and in the isolated PSI core complex of spinach under conditions in which the terminal electron donor P700 is chemically pre-oxidised. It is shown that, under these conditions, the relaxation of the excited state is characterised by lifetimes of about 0.4 ps, 4.5 ps, 15 ps, 35 ps and 65 ps in PSI-LHCI and 0.15 ps, 0.3 ps, 6 ps and 16 ps in the PSI core complex. Compartmental spectral-kinetic modelling indicates that the most likely mechanism to explain the absence of long-lived (ns) excited states is the photochemical population of a radical pair state, which cannot be further stabilised and decays non-radiatively to the ground state with time constants in the order of 6-8 ps.

中文翻译：

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陆地植物光系统I核心和整个超复合物在氧化电子给体条件下的超快激发态动力学。

通过飞秒瞬态吸收研究了激发态能量迁移的动力学，该过程是在末端电子给体P700为化学预氧化。结果表明，在这些条件下，激发态的弛豫的特征是在PSI-LHCI中的寿命分别为0.4 ps，4.5 ps，15 ps，35 ps和65 ps，以及0.15 ps，0.3 ps，6 ps和16的寿命。 PSI核心复合物中的ps。室光谱动力学模型表明，最能解释长寿（ns）激发态不存在的机制是自由基对态的光化学种群，