Chlorobaculum tepidum lives in low-light conditions and relies on highly efficient solar energy harvesting to survive. This process is mediated by the Fenna-Matthews-Olson complex, which quickly transports energy from the Chlorosomes to their reaction centers. The transport is facilitated by several coupled chromophores, precisely arranged so that their energy structure tilts downhill toward the reaction center. Knowledge of the exciton energies is important for understanding the system’s dynamics. For nearly two decades, researchers have characterized the complex’s highly overlapping Qy band transition energies. To complicate matters further, an eighth chromophore was reported relatively recently. We employ two techniques, 2D electronic spectroscopy and the hierarchical equations of motion, to study the eight-exciton transient spectral structure. New analytical techniques are applied to bypass much of the inhomogeneous broadening that usually obscures the individual peak structure in two-dimensional spectra, revealing 2D spectra in unprecedented detail. In particular, we clearly distinguish exciton 8’s diagonal and cross peaks.

Resolving the detailed 2D spectral structure of the Fenna-Matthews-Olson complex

253rd National Meeting (2017)

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