The kinetics of excitation energy transfer and charge separation process in the photosynthetic reaction center of Heliobacterium modesticaldum were investigated with femtosecond transient absorption spectroscopy at room temperature. This is the first report using the highly purified reaction center isolated from heliobacteria. The bacteriochlorophyll (BChl) g pigment pool was selectively excited at its Q_y band of 810 nm. The transient difference spectra were structured enough to be assigned to major pigment pools (B_md787, B_md800, and B_md812), despite the broad absorption spectrum of the Q_y region at room temperature. The spectral equilibration among three different spectral pools completed in less than 0.2 ps, indicating a very rapid energy transfer process because of the strong excitonic interaction between BChl gs. The decay-associated difference spectra (DADS) obtained by a global fit analysis from 450 nm to 900 nm revealed a very rapid energy transfer process and a subsequent trapping, with a time constant of 20 ps, to form the initial charge separation state of P800⁺A₀^–. The 20 ps component showed the bleaching Q_y band at 816 nm and would derive from the excited red-BChl gs or might be due to the exciton coupling between P800 and a monomeric accessory BChl g. Furthermore, the non-decaying component spectrum exhibited a slightly broader peak centered at 792 nm, ascribed to the overlapping of two bleaching bands derived from both the P800 itself and an accessory BChl g excitonically coupled with the primary acceptor 8¹−OH-Chl a_F. This was supported by the appearance of another bleaching band at 573 nm, which was detected in the Q_x region of BChl gs.

用飞秒瞬态吸收光谱法研究了在空果Heliobacterdticaldum光合反应中心中激发能转移和电荷分离过程的动力学。这是首次使用从Heliobacteria中分离出的高度纯化的反应中心的报道。叶绿素（BChl）g色素库在其810 nm的Q _y波段被选择性激发。尽管Q _y具有宽吸收光谱，但瞬态差异光谱的结构足以分配给主要颜料库（B _md 787，B _md 800和B _md 812）。室温下的区域。三个不同光谱池之间的光谱平衡在不到0.2 ps的时间内完成，这表明由于BChl g s之间强烈的激子相互作用，能量转移过程非常迅速。通过从450 nm至900 nm的全局拟合分析获得的与衰变相关的差异光谱（DADS）显示了非常快速的能量转移过程以及随后的俘获，其时间常数为20 ps，形成了P800的初始电荷分离状态⁺ A ₀ ^–。20 ps分量在816 nm处显示出漂白Q _y谱带，并且可能是由激发的红色BChl g s引起的，或者可能是由于P800与单体附件BChl g之间的激子耦合所致。。此外，非衰减频谱分量表现出略宽的峰值为中心在792纳米，归因于从两个P800本身导出的两个漂白带的重叠和附件BCHL克excitonically加上初级受体8 ¹ -OH-CHL一个_˚F。这在573 nm处出现了另一个漂白带，这是在BChl g s的Q _x区域中检测到的。