Consistent Model of Ultrafast Energy Transfer in Peridinin Chlorophyll-a Protein Using Two-Dimensional Electronic Spectroscopy and Förster Theory
| Autor: | Chanelle C. Jumper, Roger G. Hiller, Gregory D. Scholes, Mary H. deGolian, Zi S. D. Toa |
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| Rok vydání: | 2019 |
| Předmět: |
Physics
Physics::Biological Physics education.field_of_study 010304 chemical physics Population Chromophore Conical intersection 010402 general chemistry 01 natural sciences Electron spectroscopy Spectral line 0104 chemical sciences Surfaces Coatings and Films chemistry.chemical_compound Peridinin chemistry Chemical physics 0103 physical sciences Materials Chemistry Physical and Theoretical Chemistry education Absorption (electromagnetic radiation) Excitation |
| Zdroj: | The Journal of Physical Chemistry B. 123:6410-6420 |
| ISSN: | 1520-5207 1520-6106 |
| Popis: | Solar light harvesting begins with electronic energy transfer in structurally complex light-harvesting antennae such as the peridinin chlorophyll-a protein from dinoflagellate algae. Peridinin chlorophyll-a protein is composed of a unique combination of chlorophylls sensitized by carotenoids in a 4:1 ratio, and ultrafast spectroscopic methods have previously been utilized in elucidating their energy-transfer pathways and timescales. However, due to overlapping signals from various chromophores and competing pathways and timescales, a consistent model of intraprotein electronic energy transfer has been elusive. Here, we used a broad-band two-dimensional electronic spectroscopy, which alleviates the spectral congestion by dispersing excitation and detection wavelengths. Interchromophoric couplings appeared as cross peaks in two-dimensional electronic spectra, and these spectral features were observed between the peridinin S2 states and chlorophyll-a Qx and Qy states. In addition, the inherently high time and frequency resolutions of two-dimensional electronic spectroscopy enabled accurate determination of the ultrafast energy-transfer dynamics. Kinetic analysis near the peridinin S1 excited-state absorption, which forms in 24 fs after optical excitation, reveals an ultrafast energy-transfer pathway from the peridinin S2 state to the chlorophyll-a Qx state, a hitherto unconfirmed pathway critical for fast interchromophoric transfer. We propose a model of ultrafast peridinin chlorophyll-a protein photophysics that includes (1) a conical intersection between peridinin S2 and S1 states to explain both the ultrafast peridinin S1 formation and the residual peridinin S2 population for energy transfer to chlorophyll-a, and (2) computationally and experimentally derived peridinin S2 site energies that support the observed ultrafast peridinin S2 to chlorophyll-a Qx energy transfer. |
| Databáze: | OpenAIRE |
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