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Cited by 242Spectroscopy and Quantum Chemical StudiesPhotochemistry and Electron Transfer StudiesPhotosynthetic Processes and Mechanisms

Vibronic Enhancement of Exciton Sizes and Energy Transport in Photosynthetic Complexes

Womick, Jordan M., Moran, Andrew M.·2011·The Journal of Physical Chemistry B
DOI 10.1021/jp106713q
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Abstract

Transport processes and spectroscopic phenomena in light harvesting proteins depend sensitively on the characteristics of electron-phonon couplings. Decoherence imposed by low-frequency nuclear motion generally suppresses the delocalization of electronic states, whereas the Franck-Condon progressions of high-frequency intramolecular modes underpin a hierarchy of vibronic Coulombic interactions between pigments. This Article investigates the impact of vibronic couplings on the electronic structures and relaxation mechanisms of two cyanobacterial light-harvesting proteins, allophycocyanin (APC) and C-phycocyanin (CPC). Both APC and CPC possess three pairs of pigments (i.e., dimers) that undergo electronic relaxation on the subpicosecond time scale. Electronic relaxation is ~10 times faster in APC than in CPC despite the nearly identical structures of their pigment dimers. We suggest that the distinct behaviors of these closely related proteins are understood on the same footing only in a basis of joint electronic-nuclear states (i.e., vibronic excitons). A vibronic exciton model predicts well-defined rate enhancements in APC at realistic values of the site reorganization energies, whereas a purely electronic exciton model points to faster dynamics in CPC. Calculated exciton sizes (i.e., participation ratios) show that wave function delocalization underlies the rate enhancement predicted by the vibronic exciton model. Strong vibronic coupling and heterogeneity in the pigment sites are the key ingredients of the vibronic delocalization mechanism. In contrast, commonly employed purely electronic exciton models see heterogeneity as only a localizing influence. This work raises the possibility that similar vibronic effects, which are often neglected, may generally have a significant influence on energy transport in molecular aggregates and photosynthetic complexes.

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  • Entanglement holds the potential to achieve higher sensitivity to external signals.

    “More sophisticated multi-particle coherence phenomena distributed across different components of a system such as entanglement hold the potential to achieve higher sensitivity to external signals [22, 23].”

    From Vibrations, quanta and biology (2013) · cites this paper as [23]

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Authors
Womick, J. M., & Moran, A. M.
Affiliations
University of North Carolina at Chapel Hill (US)
Corresponding author
Moran, Andrew M.
ORCID
Moran, Andrew M.
Venue
The Journal of Physical Chemistry B
Publisher
American Chemical Society (ACS)
Published
2011-01-26
Volume
115
Issue
6
Pages
1347-1356
ISSN
  • 1520-5207 (ISSN-L)
  • 1520-6106
DOI
10.1021/jp106713q
OpenAlex
W2088488090
Cited by
242
References
66
Citations by year
2026: 10 · 2025: 9 · 2024: 14 · 2023: 11 · 2022: 14 · 2021: 9 · 2020: 17 · 2019: 19 · 2018: 19 · 2017: 24 · 2016: 15 · 2015: 31 · 2014: 16 · 2013: 11 · 2012: 14
FWCI
8.33
Type
journal article
Language
en
Open access
closed
Locations
  • The Journal of Physical Chemistry B (publishedVersion)
  • PubMed (publishedVersion)
Funders
  • National Science Foundation
  • Division of Chemistry
Topics
  • Physical Sciences › Physics and Astronomy › Atomic and Molecular Physics, and Optics › Spectroscopy and Quantum Chemical Studies
  • Physical Sciences › Chemistry › Physical and Theoretical Chemistry › Photochemistry and Electron Transfer Studies
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Photosynthetic Processes and Mechanisms
Keywords
exciton size, energy transport, allophycocyanin, C-phycocyanin, electron-phonon coupling, electronic relaxation, wave function delocalization, participation ratio, exciton model, photosynthetic complexes
MeSH terms
Energy Transfer, Models, Molecular, Phycocyanin, Quantum Theory, Dimerization, Light-Harvesting Protein Complexes

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