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Origin of long-lived coherences in light-harvesting complexes.

ABSTRACT: A vibronic exciton model is applied to explain the long-lived oscillatory features in the two-dimensional (2D) electronic spectra of the Fenna-Matthews-Olson (FMO) complex. Using experimentally determined parameters and uncorrelated site energy fluctuations, the model predicts oscillations with dephasing times of 1.3 ps at 77 K, which is in a good agreement with the experimental results. These long-lived oscillations originate from the coherent superposition of vibronic exciton states with dominant contributions from vibrational excitations on the same pigment. The oscillations obtain a large amplitude due to excitonic intensity borrowing, which gives transitions with strong vibronic character a significant intensity despite the small Huang-Rhys factor. Purely electronic coherences are found to decay on a 200 fs time scale.

SUBMITTER: Christensson N

PROVIDER: S-EPMC3789255 | biostudies-literature | 2012 Jun

REPOSITORIES: biostudies-literature

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Origin of long-lived coherences in light-harvesting complexes.

Christensson Niklas N Kauffmann Harald F HF Pullerits Tõnu T Mančal Tomáš T

The journal of physical chemistry. B 20120614 25

A vibronic exciton model is applied to explain the long-lived oscillatory features in the two-dimensional (2D) electronic spectra of the Fenna-Matthews-Olson (FMO) complex. Using experimentally determined parameters and uncorrelated site energy fluctuations, the model predicts oscillations with dephasing times of 1.3 ps at 77 K, which is in a good agreement with the experimental results. These long-lived oscillations originate from the coherent superposition of vibronic exciton states with domin ...[more]

PMID: 22642682

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