Vibrational Modes Promoting Exciton Relaxation in the B850 Band of LH2

Jun Woo Kim, Tu C. Nguyen-Phan, Alastair T. Gardiner, Tai Hyun Yoon, Richard J. Cogdell, Minhaeng Cho, Gregory D. Scholes

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8 Citations (Scopus)


Exciton relaxation dynamics in multichromophore systems are often modeled using Redfield theory, where bath fluctuations mediate the relaxation among the exciton eigenstates. Identifying the vibrational or phonon modes that are implicated in exciton relaxation allows more detailed understanding of exciton dynamics. Here we focus on a well-studied light-harvesting II complex (LH2) isolated from the photosynthetic purple bacterium Rhodoblastus acidophilus strain 10050. Using two synchronized mode-locked lasers, we carried out a polarization-dependent two-dimensional electronic spectroscopy (2DES) study of an ultrafast exciton relaxation in the B850 band of LH2. 2DES data with different polarization configurations enable us to investigate the exciton relaxation between the k = ±1 exciton states. Then, we identify vibrational modes coupled to the exciton relaxation by analyzing the coherent wavepackets in the 2DES signals. Focusing on the coherent vibrational wavepackets, the data suggest that certain symmetry-breaking modes of monomeric units play a key role in exciton relaxation.

Original languageEnglish
Pages (from-to)1099-1106
Number of pages8
JournalJournal of Physical Chemistry Letters
Issue number4
Publication statusPublished - 2022 Feb 3

Bibliographical note

Funding Information:
This material is based upon work supported by the U.S. Department of Energy, Office of Basic Energy Sciences under contract DE-SC0020437 (J.K. and G.D.S.) and the Institute for Basic Science in Korea (IBS-R23-D1, T.H.Y. and M.C.). T.C.N. and R.J.C. were supported by BBSRC grant n. BB/N0166734/1. A.T.G. and R.J.C. gratefully acknowledge funding from the Photosynthetic Antenna Research Center, an Energy Research Center funded by the Department of Energy, Office of Basic Energy Sciences, under award no. DE-SC0001035. All the experimental data were taken while J.K. visited the CMSD-IBS. We thank Dr. Noh Soo Hahn and Mr. Hyunmin Chang, who contributed to the maintenance of the frequency comb laser facility in the CMSD-IBS in Korea. We thank Professor Jeff Cina for discussions and comments on the manuscript.

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ASJC Scopus subject areas

  • General Materials Science
  • Physical and Theoretical Chemistry


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