Coherent oscillations in chlorosome elucidated by two-dimensional electronic spectroscopy

Sunhong Jun, Cheolhee Yang, Megumi Isaji, Hitoshi Tamiaki, Jeongho Kim, Hyotcherl Ihee

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

Chlorosomes are the most efficient photosynthetic light-harvesting complexes found in nature and consist of many bacteriochlorophyll (BChl) molecules self-assembled into supramolecular aggregates. Here we elucidate the presence and the origin of coherent oscillations in chlorosome at cryogenic temperature using 2D electronic spectroscopy. We observe coherent oscillations of multiple frequencies superimposed on the ultrafast amplitude decay of 2D spectra. Comparison of oscillatory features in the rephasing and nonrephasing 2D spectra suggests that an oscillation of 620 cm-1 frequency arises from electronic coherence. However, this coherent oscillation can be enhanced by vibronic coupling with intermolecular vibrations of BChl aggregate, and thus it might originate from vibronic coherence rather than pure electronic coherence. Although the 620 cm-1 oscillation dephases rapidly, the electronic (or vibronic) coherence may still take part in the initial step of energy transfer in chlorosome, which is comparably fast.

Original languageEnglish
Pages (from-to)1386-1392
Number of pages7
JournalJournal of Physical Chemistry Letters
Volume5
Issue number8
DOIs
StatePublished - 17 Apr 2014

Keywords

  • chlorosome
  • coherent oscillation
  • electronic coherence
  • energy transfer
  • two-dimensional electronic spectroscopy

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