Advanced

The nature of coherences in the B820 bacteriochlorophyll dimer revealed by two-dimensional electronic spectroscopy

Ferretti, Marco; Novoderezhkin, Vladimir I.; Romero, Elisabet; Augulis, Ramunas LU ; Pandit, Anjali; Zigmantas, Donatas LU and van Grondelle, Rienk (2014) In Physical Chemistry Chemical Physics 16(21). p.9930-9939
Abstract
Light-harvesting in photosynthesis is determined by the excitonic interactions in disordered antennae and the coupling of collective electronic excitations to fast nuclear motions, producing efficient energy transfer with a complicated interplay between exciton and vibrational coherences. Two-dimensional electronic spectroscopy (2DES) is a powerful tool to study the presence of these coherences in photosynthetic complexes. However, the unambiguous assignment of the nature of the observed coherences is still under debate. In this paper we apply 2DES to an excitonically coupled bacteriochlorophyll dimer, the B820 subunit of the light harvesting complex 1 (LH1-RC) of R. rubrum G9. Fourier analysis of the measured kinetics and modeling of the... (More)
Light-harvesting in photosynthesis is determined by the excitonic interactions in disordered antennae and the coupling of collective electronic excitations to fast nuclear motions, producing efficient energy transfer with a complicated interplay between exciton and vibrational coherences. Two-dimensional electronic spectroscopy (2DES) is a powerful tool to study the presence of these coherences in photosynthetic complexes. However, the unambiguous assignment of the nature of the observed coherences is still under debate. In this paper we apply 2DES to an excitonically coupled bacteriochlorophyll dimer, the B820 subunit of the light harvesting complex 1 (LH1-RC) of R. rubrum G9. Fourier analysis of the measured kinetics and modeling of the spectral responses in a complete basis of electronic and vibrational states allow us to distinguish between pure vibrational, mixed exciton-vibrational (vibronic), and predominantly exciton coherences. The mixed coherences have been found in a wide range of oscillation frequencies, whereas exciton coherences give the biggest contributions for the frequencies in the 400-550 cm(-1) range, corresponding to the exciton splitting energy of the B820 dimer. Significant exciton coherences are also present at higher frequencies, i.e., up to 800 cm(-1), which are determined by realizations of the disorder with a large energy gap between the two pigments (which increases the apparent value of the exciton splitting). Although the B820 dimer is a model system, the approach presented here represents a basis for further analyses of more complicated systems, providing a tool for studying the interplay between electronic and vibrational coherences in disordered photosynthetic antennae and reaction centres. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Physical Chemistry Chemical Physics
volume
16
issue
21
pages
9930 - 9939
publisher
Royal Society of Chemistry
external identifiers
  • wos:000335924800020
  • scopus:84899888742
ISSN
1463-9084
DOI
10.1039/c3cp54634a
language
English
LU publication?
yes
id
10976f3a-5a52-4811-9c42-1f96b404d69b (old id 4470458)
date added to LUP
2014-07-01 07:37:32
date last changed
2017-09-24 04:05:43
@article{10976f3a-5a52-4811-9c42-1f96b404d69b,
  abstract     = {Light-harvesting in photosynthesis is determined by the excitonic interactions in disordered antennae and the coupling of collective electronic excitations to fast nuclear motions, producing efficient energy transfer with a complicated interplay between exciton and vibrational coherences. Two-dimensional electronic spectroscopy (2DES) is a powerful tool to study the presence of these coherences in photosynthetic complexes. However, the unambiguous assignment of the nature of the observed coherences is still under debate. In this paper we apply 2DES to an excitonically coupled bacteriochlorophyll dimer, the B820 subunit of the light harvesting complex 1 (LH1-RC) of R. rubrum G9. Fourier analysis of the measured kinetics and modeling of the spectral responses in a complete basis of electronic and vibrational states allow us to distinguish between pure vibrational, mixed exciton-vibrational (vibronic), and predominantly exciton coherences. The mixed coherences have been found in a wide range of oscillation frequencies, whereas exciton coherences give the biggest contributions for the frequencies in the 400-550 cm(-1) range, corresponding to the exciton splitting energy of the B820 dimer. Significant exciton coherences are also present at higher frequencies, i.e., up to 800 cm(-1), which are determined by realizations of the disorder with a large energy gap between the two pigments (which increases the apparent value of the exciton splitting). Although the B820 dimer is a model system, the approach presented here represents a basis for further analyses of more complicated systems, providing a tool for studying the interplay between electronic and vibrational coherences in disordered photosynthetic antennae and reaction centres.},
  author       = {Ferretti, Marco and Novoderezhkin, Vladimir I. and Romero, Elisabet and Augulis, Ramunas and Pandit, Anjali and Zigmantas, Donatas and van Grondelle, Rienk},
  issn         = {1463-9084},
  language     = {eng},
  number       = {21},
  pages        = {9930--9939},
  publisher    = {Royal Society of Chemistry},
  series       = {Physical Chemistry Chemical Physics},
  title        = {The nature of coherences in the B820 bacteriochlorophyll dimer revealed by two-dimensional electronic spectroscopy},
  url          = {http://dx.doi.org/10.1039/c3cp54634a},
  volume       = {16},
  year         = {2014},
}