4.6 Article

Exciton delocalization length in chlorosomes investigated by lineshape dynamics of two-dimensional electronic spectra

Journal

PHYSICAL CHEMISTRY CHEMICAL PHYSICS
Volume 23, Issue 42, Pages 24111-24117

Publisher

ROYAL SOC CHEMISTRY
DOI: 10.1039/d1cp03413h

Keywords

-

Funding

  1. Institute for Basic Science [IBS-R004]
  2. National Research Foundation of Korea (NRF) - Ministry of Science, ICT and Future Planning [2016R1E1A1A01941978, 2021R1F1A1048431]
  3. National Research Foundation of Korea [2021R1F1A1048431] Funding Source: Korea Institute of Science & Technology Information (KISTI), National Science & Technology Information Service (NTIS)

Ask authors/readers for more resources

In this study, the exciton delocalization length (EDL) in chlorosomes was determined using two-dimensional electronic spectroscopy (2D-ES). The EDL was found to vary with temperature and excitation frequency, with high-frequency phonons being more activated at 298 K compared to 77 K. The research provides insights into the energy transfer processes in chlorosomes under different conditions.
A chlorosome, a photosynthetic light-harvesting complex found in green sulfur bacteria, is an aggregate of self-assembled pigments and is optimized for efficient light harvesting and energy transfer under dim-light conditions. In this highly-disordered aggregate, the absorption and transfer of photoexcitation energy are governed by the degree of disorder. To describe the disorder, the number of molecules forming excitons, which is termed exciton delocalization length (EDL), is a relevant parameter because the EDL sensitively changes with the disorder of the constituent molecules. In this work, we determined the EDL in chlorosomes using two-dimensional electronic spectroscopy (2D-ES). Since spectral features correlated with EDL are spread out in the two-dimensional (2D) electronic spectra, we were able to determine the EDL accurately without the effects of homogeneous and inhomogeneous line broadening. In particular, by taking advantage of the multi-dimensionality and the time evolution of 2D spectra, we not only determined the excitation frequency dependence of EDL but also monitored the temporal change of EDL. We found that the EDL is similar to 7 at 77 K and similar to 6 at 298 K and increases with the excitation frequency, with the maximum located well above the maximum of the absorption spectrum of chlorosomes. The spectral profile of EDL changes rapidly within 100 fs and becomes flat over time due to dephasing of initial exciton coherence. From the coherent oscillations superimposed on the decay of EDL, it was learned that high-frequency phonons are more activated at 298 K than at 77 K.

Authors

I am an author on this paper
Click your name to claim this paper and add it to your profile.

Reviews

Primary Rating

4.6
Not enough ratings

Secondary Ratings

Novelty
-
Significance
-
Scientific rigor
-
Rate this paper

Recommended

No Data Available
No Data Available