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Title: Dark States in the Light-Harvesting complex 2 Revealed by Two-dimensional Electronic Spectroscopy

Energy transfer and trapping in the light harvesting antennae of purple photosynthetic bacteria is an ultrafast process, which occurs with a quantum efficiency close to unity. However the mechanisms behind this process have not yet been fully understood. Recently it was proposed that low-lying energy dark states, such as charge transfer states and polaron pairs, play an important role in the dynamics and directionality of energy transfer. However, it is difficult to directly detect those states because of their small transition dipole moment and overlap with the B850/B870 exciton bands. Here we present a new experimental approach, which combines the selectivity of two-dimensional electronic spectroscopy with the availability of genetically modified light harvesting complexes, to reveal the presence of those dark states in both the genetically modified and the wild-type light harvesting 2 complexes of Rhodopseudomonas palustris. In conclusion, we suggest that Nature has used the unavoidable charge transfer processes that occur when LH pigments are concentrated to enhance and direct the flow of energy.
 [1] ;  [1] ;  [1] ;  [2] ;  [2] ;  [3] ;  [4] ;  [1]
  1. Vrije Univ., Amsterdam (Netherlands). Department of Physics and Astronomy
  2. Univ. of Glasgow, Scotland (United Kingdom). Division of Biochemistry and Molecular Biology
  3. Moscow State Univ., Moscow (Russia). A. N. Belozersky Institute of Physico-Chemical Biology
  4. Princeton Univ., NJ (United States). Dept. of Chemistry
Publication Date:
OSTI Identifier:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 6; Journal ID: ISSN 2045-2322
Nature Publishing Group
Research Org:
Vrije Univ., Amsterdam (Netherlands)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States