抄録
Subpicosecond time-resolved absorption spectra were recorded, in visible and near-infrared regions, for the LH2 antenna complexes from Rhodobacter (Rba.) sphaeroides G1C, Rba. sphaeroides 2.4.1, Rhodospirillum (Rsp.) molischianum, and Rhodopseudomonas (Rsp.) acidophila. The efficiencies of carotenoid-to-bacteriochlorophyll singlet energy-transfer through the 11Bu+, 11Bu-, and 21Ag- channels in the LH2 complex were determined to be 48, 19 and 22% in Rba. sphaeroides G1C; 46, 18 and 20% in Rba. sphaeroides 2.4.1; 48, ∼2 and ∼1% in Rsp. molischianum; and 48, ∼2, ∼4% in Rps. acidophila. Sums of efficiencies in the four LH2 complexes, 88, 84, 51 and 54%, nicely correlate with the efficiencies that were determined by comparison of the absorption and fluorescence-excitation spectra, 92, 89, 53 and 56%. It was also found that the triplet 13Bu (T1) state of Car is generated rapidly from the 11Bu- state in the four LH2 complexes, carrying energies of 10, 12, 17 and 16%.
