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

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

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 (US)
Pages (from-to)1099-1106
Number of pages8
JournalJournal of Physical Chemistry Letters
Volume13
Issue number4
DOIs
StatePublished - Feb 3 2022

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Physical and Theoretical Chemistry

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