EXCITATION DELOCALIZATION IN THE BACTERIOCHLOROPHYLL-C ANTENNA OF THEGREEN BACTERIUM CHLOROFLEXUS-AURANTIACUS AS REVEALED BY ULTRAFAST PUMP-PROBE SPECTROSCOPY

Room temperature absorption difference spectra were measured on the fe mtosecond through picosecond time scales for chlorosomes isolated from the green bacterium Chloroflexus aurantiacus. Anomalously high values of photoinduced absorption changes were revealed in the BChl c Qy tra nsition band. Photoinduced absorption changes at the bleaching peak in the BChl c band were found to be 7-8 times greater than those at the bleaching peak in the BChl a band of the chlorosome, This appears to b e the first direct experimental proof of excitation delocalization ove r many BChl c antenna molecules in the chlorosome, (C) 1998 Federation of European Biochemical Societies.