Ultrafast excitation relaxation in light-harvesting complex LH2 from Rb.sphaeroides 601  

作　　者：GUO Lijun1,2, LIU Yuan3, LIU Weimin2, GUO Junhua1, XU Chunhe3 & QIAN Shixiong2 1. School of Physics and Information Optoelectronics, Henan University, Kaifeng 475001, China 2. Physics Department, Fudan University, Shanghai 200433, China 3. Shanghai Institute of Plant Physiology, Chinese Academy of Sciences, Shanghai 200032, China 

出　　处：《Science China Chemistry》2004年第3期192-199,共8页中国科学（化学英文版）

基　　金：the National Natural Science Foundation of China(Grant No.10274013);State Key Basic Research and Development Plan(Grant No.G1998010100);Natural Science Foundation of Henan Educational Committee(Grant No.20011400003);the Key Natural Science Foundation of Henan University.

摘　　要：The energy relaxation and kinetic evolution of transient spectra of bacteriochloro- phylls (BChls) in light-harvesting complex LH2 from Rb. sphaeroides 601 were investigated using femtosecond pump-probe technique. Upon 783 nm excitation, the energy at B800 BChls ex-periences an intramolecular redistribution with 0.35 ps time constant before transferring to B850 BChls. With tuning the excitation wavelength, the dynamical evolution of excited BChls was clearly observed, which indicates an obvious competition between the ground state bleaching and excited state absorption (ESA) of BChls involved and an isosbestic point near 818 nm, and also demonstrates that from the lower electronic excited state of B800 BChls to the higher exci-tonic state of B850 BChls is an efficient routine for energy transfer. The excitation energy in higher excitonic states of B850 BChls relaxes rapidly to the next lowest excitonic state by inter-conversion, delocalization to adjacent molecular, populating the lowest excitonic state and the change of molecular conformation.The energy relaxation and kinetic evolution of transient spectra of bacteriochlorophylls (BChls) in light-harvesting complex LH2 from Rb. sphaeroides 601 were investigated using femtosecond pump-probe technique. Upon 783 nm excitation, the energy at B800 BChls experiences an intramolecular redistribution with 0.35 ps time constant before transferring to B850 BChls. With tuning the excitation wavelength, the dynamical evolution of excited BChls was clearly observed, which indicates an obvious competition between the ground state bleaching and excited state absorption (ESA) of BChls involved and an isosbestic point near 818 nm, and also demonstrates that from the lower electronic excited state of B800 BChls to the higher excitonic state of B850 BChls is an efficient routine for energy transfer. The excitation energy in higher excitonic states of B850 BChls relaxes rapidly to the next lowest excitonic state by interconversion, delocalization to adjacent molecular, populating the lowest excitonic state and the change of molecular conformation.

关 键 词：photosynthesis  LIGHT-HARVESTING complex  energy transfer  ultrafast  dynamics  PURPLE bacteria. 

分 类 号：Q945[生物学—植物学]