Chiroptical nature of two-exciton states of light-harvesting complex: Doubly resonant three-wave-mixing spectroscopy

Hochan Lee, Sangheon Cheon, Minhaeng Cho

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


Photosynthetic light-harvesting complex is a coupled multichromophore system. Due to electronic couplings between neighboring chlorophylls in the complex, the one- and two-exciton states are delocalized and they can be written as linear combinations of singly and doubly excited configurations, respectively. Despite that the chiroptical properties of one-exciton states in such a multichromophore system have been investigated by using linear optical activity measurement techniques; those of two-exciton states have not been studied before due to a lack of appropriate measurement methods. Here, we present a theoretical description on chiroptical (2) spectroscopy and show that it can be used to investigate such properties of a photosynthetic light-harvesting system, which is the Fenna-Matthews-Olson complex, consisting of seven bacteriochlorophylls in its protein subunit. To simulate the doubly resonant sum- and difference-frequency-generation spectra of the complex, one- and two-exciton transition dipoles were calculated. Carrying out quantum chemistry calculations of electronically excited states of a model bacteriochlorophyll system and taking into account the dipole-induced dipole electronic transition processes between the ground state and two-exciton states, we could calculate the two-dimensional sum-frequency-generation spectra revealing dominant second-order chiroptical transition pathways and involved one- and two-exciton states. It is believed that the present computational scheme and the theoretically proposed doubly resonant two-dimensional three-wave-mixing spectroscopy would be of use to shed light on the chiroptical natures of two-exciton states of arbitrary coupled multichromophore systems.

Original languageEnglish
Article number225102
JournalJournal of Chemical Physics
Issue number22
Publication statusPublished - 2010 Jun 14

Bibliographical note

Funding Information:
This work was supported by NRF (Grant No. 20090078897) and KBSI (Grant No. T30401).

ASJC Scopus subject areas

  • General Physics and Astronomy
  • Physical and Theoretical Chemistry


Dive into the research topics of 'Chiroptical nature of two-exciton states of light-harvesting complex: Doubly resonant three-wave-mixing spectroscopy'. Together they form a unique fingerprint.

Cite this