How exciton-vibrational coherences control charge separation in the photosystem II reaction center

V.I. Novoderezhkin, E. Romero Mesa, R. van Grondelle

Research output: Contribution to JournalArticle

Abstract

In photosynthesis absorbed sun light produces collective excitations (excitons) that form a coherent superposition of electronic and vibrational states of the individual pigments. Two-dimensional (2D) electronic spectroscopy allows a visualization of how these coherences are involved in the primary processes of energy and charge transfer. Based on quantitative modeling we identify the exciton-vibrational coherences observed in 2D photon echo of the photosystem II reaction center (PSII-RC). We find that the vibrations resonant with the exciton splittings can modify the delocalization of the exciton states and produce additional states, thus promoting directed energy transfer and allowing a switch between the two charge separation pathways. We conclude that the coincidence of the frequencies of the most intense vibrations with the splittings within the manifold of exciton and charge-transfer states in the PSII-RC is not occurring by chance, but reflects a fundamental principle of how energy conversion in photosynthesis was optimized.
Original languageEnglish
Pages (from-to)30828-30841
JournalPhysical Chemistry Chemical Physics - PCCP
Volume17
Issue number46
DOIs
Publication statusPublished - 2015

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