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Coupling to Charge Transfer States is the Key to Modulate the Optical Bands for Efficient Light Harvesting in Purple Bacteria
- Source :
- The Journal of Physical Chemistry Letters. 9:6892-6899
- Publication Year :
- 2018
- Publisher :
- American Chemical Society (ACS), 2018.
-
Abstract
- The photosynthetic apparatus of purple bacteria uses exciton delocalization and static disorder to modulate the position and broadening of its absorption bands, leading to efficient light harvesting. Its main antenna complex, LH2, contains two rings of identical bacteriochlorophyll pigments, B800 and B850, absorbing at 800 and 850 nm, respectively. It has been an unsolved problem why static disorder of the strongly coupled B850 ring is several times larger than that of the B800 ring. Here we show that mixing between excitons and charge transfer states in the B850 ring is responsible for the effect. The linear absorption spectrum of the LH2 system is simulated by using a multiscale approach with an exciton Hamiltonian generalized to include the charge transfer states that involve adjacent pigment pairs, with static disorder modeled microscopically by molecular dynamics simulations. Our results show that sufficient inhomogeneous broadening of the B850 band, needed for efficient light harvesting, is only obtained by utilizing static disorder in the coupling between local excited and interpigment charge transfer states.
- Subjects :
- Materials science
Absorption spectroscopy
Protein Conformation
Exciton
Light-Harvesting Protein Complexes
Molecular Dynamics Simulation
010402 general chemistry
01 natural sciences
Purple bacteria
Molecular physics
chemistry.chemical_compound
Delocalized electron
Proteobacteria
0103 physical sciences
General Materials Science
Photosynthesis
Physical and Theoretical Chemistry
Absorption (electromagnetic radiation)
Bacteriochlorophylls
Physics::Biological Physics
Binding Sites
010304 chemical physics
biology
Charge (physics)
Materials Science (all)
biology.organism_classification
0104 chemical sciences
chemistry
Excited state
Thermodynamics
Bacteriochlorophyll
Subjects
Details
- ISSN :
- 19487185
- Volume :
- 9
- Database :
- OpenAIRE
- Journal :
- The Journal of Physical Chemistry Letters
- Accession number :
- edsair.doi.dedup.....43204966707c1c9afaee1c6515a03a68
- Full Text :
- https://doi.org/10.1021/acs.jpclett.8b03233