Three pulse echo peak shift measurements on the B820 subunit of LH1 of Rhodospirillum rubrum

Three pulse photon echo peak shift measurements (3PEPS) of the detergent isolated B820 subunit of the light harvesting complex of Rhodospirillum rubrum are presented and compared with 3PEPS data for the LH1 complex of Rhodobacter sphaeroides. The comparison suggests that the 90 fs component of LH1 3PEPS is indeed the energy transfer component. The striking similarity between 3PEPS of LH1 and B820 subunit also suggests that excitation is delocalized over only a dimer unit.