IFN Consiglio Nazionale delle Ricerche, Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milan, Italy.
Photosynthesis Research Unit, Centro Studi sulla Biologia Cellulare e Molecolare delle Piante, Consiglio Nazionale delle Ricerche, Via Celoria 26, 20133, Milan, Italy.
Photosynth Res. 2020 May;144(2):221-233. doi: 10.1007/s11120-020-00717-y. Epub 2020 Feb 12.
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 P 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.
通过飞秒瞬态吸收研究了激发态能量迁移的动力学，分别在分离的Photosystem I-Light-Harvesting Complex I（PSI-LHCI）超复合体和菠菜的分离 PSI 核心复合体中进行，在这些条件下，末端电子供体 P 被化学预氧化。结果表明，在这些条件下，激发态的弛豫具有约 0.4 ps、4.5 ps、15 ps、35 ps 和 65 ps 的寿命，在 PSI-LHCI 中，在 PSI 核心复合体中为 0.15 ps、0.3 ps、6 ps 和 16 ps。隔室光谱动力学模型表明，解释不存在长寿命（ns）激发态的最可能机制是自由基对态的光化学种群，其不能进一步稳定，并随着时间常数以 6-8 ps 的顺序非辐射地衰减到基态。
