biostudies-literatureCohen Stuart TAU.S. Department of EnergyNetherlands Organization for Scientific Research Chemical SciencesDutch Research Council (NWO)European Commission's Seventh Framework ProgramEuropean Commission FP7Biotechnology and Biological Sciences Research CouncilDutch Foundation for Earth and Life Sciences2226-33https://www.ebi.ac.uk/biostudies/studies/S-EPMC3149263biostudies-literatureUnknown100(9)The dynamics of the excited states of the light-harvesting complexes LH1 and LH2 of Rhodobacter sphaeroides are governed, mainly, by the excitonic nature of these ring-systems. In a pump-dump-probe experiment, the first pulse promotes LH1 or LH2 to its excited state and the second pulse dumps a portion of the excited state. By selective dumping, we can disentangle the dynamics normally hidden in the excited-state manifold. We find that by using this multiple-excitation technique we can visualize a 400-fs reequilibration reflecting relaxation between the two lowest exciton states that cannot be directly explored by conventional pump-probe. An oscillatory feature is observed within the exciton reequilibration, which is attributed to a coherent motion of a vibrational wavepacket with a period of ∼150 fs. Our disordered exciton model allows a quantitative interpretation of the observed reequilibration processes occurring in these antennas.Biophysical journalDirect visualization of exciton reequilibration in the LH1 and LH2 complexes of Rhodobacter sphaeroides by multipulse spectroscopy.PMC3149263700-53-307228334834-01-002BB/G021546/1FP7_228334DE-SC 0001035Hunter CNNovoderezhkin VICogdell RJvan Grondelle RCohen Stuart TAVengris MfalseDirect visualization of exciton reequilibration in the LH1 and LH2 complexes of Rhodobacter sphaeroides by multipulse spectroscopy.The dynamics of the excited states of the light-harvesting complexes LH1 and LH2 of Rhodobacter sphaeroides are governed, mainly, by the excitonic nature of these ring-systems. In a pump-dump-probe experiment, the first pulse promotes LH1 or LH2 to its excited state and the second pulse dumps a portion of the excited state. By selective dumping, we can disentangle the dynamics normally hidden in the excited-state manifold. We find that by using this multiple-excitation technique we can visualize a 400-fs reequilibration reflecting relaxation between the two lowest exciton states that cannot be directly explored by conventional pump-probe. An oscillatory feature is observed within the exciton reequilibration, which is attributed to a coherent motion of a vibrational wavepacket with a period of ∼150 fs. Our disordered exciton model allows a quantitative interpretation of the observed reequilibration processes occurring in these antennas.2011-01-01T00:00:00Z2011 May2025-04-21T13:53:36.056Z2019-03-27T03:07:41ZS-EPMC31492632153979110.1016/j.bpj.2011.02.048