Memory-Assisted Exciton Diffusion in the Chlorosome Light-Harvesting Antenna of Green Sulfur Bacteria.
Chlorosomes are likely the largest and most efficient natural light-harvesting photosynthetic antenna systems. They are composed of large numbers of bacteriochlorophylls organized into supramolecular aggregates. We explore the microscopic origin of the fast excitation energy transfer in the chlorosome using the recently resolved structure and atomistic-detail simulations. Despite the dynamical disorder effects on the electronic transitions of the bacteriochlorophylls, our simulations show that the exciton delocalizes over the entire aggregate in about 200 fs. The memory effects associated to the dynamical disorder assist the exciton diffusion through the aggregates and enhance the diffusion coefficients as a factor of 2 as compared to the model without memory. Furthermore, exciton diffusion in the chlorosome is found to be highly anisotropic with the preferential transfer toward the baseplate, which is the next functional element in the photosynthetic system.
†Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States.
Takatoshi
T
Fujita
†Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States.|‡Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT.
Jennifer C
JC
Brookes
†Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States.
Semion K
SK
Saikin
†Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States.
Alán
A
Aspuru-Guzik
chlorosome; excitation energy transfer; exciton diffusion; exciton-vibration coupling; green sulfur bacteria; light-harvesting antenna system; non-Markovian effects