Identification and characterization of diverse coherences in the Fenna-Matthews-Olson complex.

摘要: The idea that excitonic (electronic) coherences are of fundamental importance to natural photosynthesis gained popularity when slowly dephasing quantum beats (QBs) were observed in the two-dimensional electronic spectra Fenna–Matthews–Olson (FMO) complex at 77 K. These assigned superpositions states, a controversial interpretation, as strong chromophore–environment interactions suggest fast dephasing. Although it has been pointed out vibrational motion produces similar spectral signatures, concrete assignment these oscillatory signals distinct physical processes is still lacking. Here we revisit coherence dynamics FMO using polarization-controlled spectroscopy, supported by theoretical modelling. We show long-lived QBs exclusively origin, whereas completed within 240 fs even further find specific produced via vibronically coupled excited states. presence such states suggests vibronic coupling relevant for photosynthetic energy transfer. implications transfer green sulfur bacteria well debated topic. Now, 2D spectroscopy — aided exciton modelling enabled characterization all and determination their origins; while dephase extremely rapidly, ground- excited-state dominate.