24 April 1998 Ultrafast studies of exciton dynamics in light-harvesting dimers
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The electronic characteristics and rapid dynamics associated with bacteriochlorophyll dimers in photosynthetic systems are investigated using novel ultrafast anisotropy techniques. The excitonic structure of isolated subunits (B820) from the core (LH-1) light harvesting complex of Rs. Rubrum and the reassociated complex (B873) is revealed in coherent anisotropy responses following impulsive excitation. For B820, the oscillatory anisotropy responses indicate excitonic splitting frequencies ranging from 370 cm-1 to 490 cm-1 indicating significant inhomogeneity in the excitonic spectrum. The complete set of wavelength dependent anisotropy result is analyzed to reveal the sources of inhomogeneity for B820; correlated distributions of dimer energetic parameters are necessary to reproduce the results. The coherent response of reassociated B873 complexes exhibit multiple frequencies, revealing the extended excitonic structure of the aggregates. In other experiments, the electronic properties of the photosynthetic reaction center and the rapid electronic dynamics prior to charge separation are investigated by both 'two color' anisotropy. A variety of excitation and detection conditions provide the first room temperature characterization of the excitonic structure of the special pair, and a detailed description of rapid energy transfer to and within the special pair. The results presented here stress the importance of delocalized excitation in both the light harvesting antenna complexes and the photosynthetic reaction center.
© (1998) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
David C. Arnett, David C. Arnett, R. Kumble, R. Kumble, R. W. Visschers, R. W. Visschers, C. C. Moser, C. C. Moser, P. L. Dutton, P. L. Dutton, Robin M. Hochstrasser, Robin M. Hochstrasser, Norbert F. Scherer, Norbert F. Scherer, } "Ultrafast studies of exciton dynamics in light-harvesting dimers", Proc. SPIE 3273, Laser Techniques for Condensed-Phase and Biological Systems, (24 April 1998); doi: 10.1117/12.306115; https://doi.org/10.1117/12.306115

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