V. Nagarajan et al., ULTRAFAST EXCITON RELAXATION IN THE B850 ANTENNA COMPLEX OF RHODOBACTER-SPHAEROIDES, Proceedings of the National Academy of Sciences of the United Statesof America, 93(24), 1996, pp. 13774-13779
Spectral changes were measured with femtosecond resolution following l
ow-intensity, broad-band excitation of the peripheral antenna complex
of the purple photosynthetic bacterium Rhodobacter sphaeroides. Absorp
tion anisotropy decays also were measured, We identified a 35-fs relax
ation of the absorption and emission spectra of the excited state, as
well as a 20-fs anisotropy decay. We interpret these results as interl
evel relaxation and dephasing, respectively, of extensively delocalize
d exciton states of the circular bacteriochlorophyll aggregate.