2015/09/30 by Sima Baghbanzadeh, Ivan Kassal
Biochemistry, Genetics and Molecular Biology · Chemistry · Physics and Astronomy · #Absorption (acoustics) #Delocalized electron #Energy transfer #Excitation #Exciton #Funnel #Light-harvesting complex #Photosynthesis #Photosynthetic Processes and Mechanisms #Spectroscopy and Quantum Chemical Studies #Synthesis and Properties of Aromatic Compounds #physics.bio-ph #physics.chem-ph #quant-ph
paper · pdf · doi:10.1039/c6cp00104a
published as Phys. Chem. Chem. Phys. 18, 7459 (2016)
openalex publication_date 2016/01/01 · arxiv created 2016/03/03 · arxiv updated 2016/03/04 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Photosynthetic complexes improve the transfer of excitation energy from peripheral antennas to reaction centers in several ways. In particular, a downward energy funnel can direct excitons in the right direction, while coherent excitonic delocalization can enhance transfer rates through the cooperative phenomenon of supertransfer. However, isolating the role of purely coherent effects is difficult because any change to the delocalization also changes the energy landscape. Here, we show that the relative importance of the two processes can be determined by comparing the natural light-harvesting apparatus with counterfactual models in which the delocalization and the energy landscape are altered. Applied to the example of purple bacteria, our approach shows that although supertransfer does enhance the rates somewhat, the energetic funnelling plays the decisive role. Because delocalization has a minor role (and is sometimes detrimental), it is most likely not adaptive, being a side-effect of the dense chlorophyll packing that evolved to increase light absorption per reaction center.