Two-dimensional spectroscopy of electronic couplings in photosynthesis

Tobias Brixner, Jens Stenger, Harsha M. Vaswani, Minhaeng Cho, Robert E. Blankenship, Graham R. Fleming

Research output: Contribution to journalArticle

893 Citations (Scopus)

Abstract

Time-resolved optical spectroscopy is widely used to study vibrational and electronic dynamics by monitoring transient changes in excited state populations on a femtosecond timescale. Yet the fundamental cause of electronic and vibrational dynamics-the coupling between the different energy levels involved-is usually inferred only indirectly. Two-dimensional femtosecond infrared spectroscopy based on the heterodyne detection of three-pulse photon echoes has recently allowed the direct mapping of vibrational couplings, yielding transient structural information. Here we extend the approach to the visible range and directly measure electronic couplings in a molecular complex, the Fenna-Matthews-Olson photosynthetic light-harvesting protein. As in all photosynthetic systems, the conversion of light into chemical energy is driven by electronic couplings that ensure the efficient transport of energy from light-capturing antenna pigments to the reaction centre. We monitor this process as a function of time and frequency and show that excitation energy does not simply cascade stepwise down the energy ladder. We find instead distinct energy transport pathways that depend sensitively on the detailed spatial properties of the delocalized excited-state wavefunctions of the whole pigment-protein complex.

Original languageEnglish
Pages (from-to)625-628
Number of pages4
JournalNature
Volume434
Issue number7033
DOIs
Publication statusPublished - 2005 Mar 31

ASJC Scopus subject areas

  • General

Fingerprint Dive into the research topics of 'Two-dimensional spectroscopy of electronic couplings in photosynthesis'. Together they form a unique fingerprint.

  • Cite this

    Brixner, T., Stenger, J., Vaswani, H. M., Cho, M., Blankenship, R. E., & Fleming, G. R. (2005). Two-dimensional spectroscopy of electronic couplings in photosynthesis. Nature, 434(7033), 625-628. https://doi.org/10.1038/nature03429