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Ultrafast Spectroscopy Reveals Significant Differences in LH2 Exciton Mobility at Cryogenic and Ambient Temperatures

Keil, Erika LU ; Malý, Pavel LU ; Cogdell, Richard J. ; Hauer, Jürgen ; Zigmantas, Donatas LU orcid and Thyrhaug, Erling LU (2026) In Journal of Physical Chemistry Letters 17(8). p.2313-2320
Abstract

Spectroscopic studies of energy transport through the photosynthetic apparatus have been crucial to expanding our understanding of biological energy conversion. Correlating spectroscopic information to the electronic structure and function in these complex systems remains highly challenging, however. While cryogenic experimental conditions help in improving the effective spectral resolution and sample stability, the observed fine-grained dynamics do not necessarily reflect in vivo functionality. To address this issue, we target the temperature dependence of energy migration in light-harvesting complex 2 of purple bacteria. Temperature- and polarization-controlled two-dimensional electronic spectroscopy reveal rapid exciton... (More)

Spectroscopic studies of energy transport through the photosynthetic apparatus have been crucial to expanding our understanding of biological energy conversion. Correlating spectroscopic information to the electronic structure and function in these complex systems remains highly challenging, however. While cryogenic experimental conditions help in improving the effective spectral resolution and sample stability, the observed fine-grained dynamics do not necessarily reflect in vivo functionality. To address this issue, we target the temperature dependence of energy migration in light-harvesting complex 2 of purple bacteria. Temperature- and polarization-controlled two-dimensional electronic spectroscopy reveal rapid exciton immobilization at low temperatures, while intensity-dependent experiments allow identification of transport barriers. We find that exciton trapping, dominating the dynamics at 80 K, becomes negligible above 150 K, implying that observations at cryogenic temperatures do not always directly reflect biological function. We additionally find that considerable care and explicit modeling may be necessary for correct interpretation of multiexciton experiments.

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author
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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Physical Chemistry Letters
volume
17
issue
8
pages
8 pages
publisher
The American Chemical Society (ACS)
external identifiers
  • pmid:41686491
  • scopus:105031276711
ISSN
1948-7185
DOI
10.1021/acs.jpclett.5c03917
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2026 The Authors. Published by American Chemical Society
id
0568e488-5d3b-4498-a52e-37adb1de6939
date added to LUP
2026-04-08 14:25:46
date last changed
2026-04-09 03:00:02
@article{0568e488-5d3b-4498-a52e-37adb1de6939,
  abstract     = {{<p>Spectroscopic studies of energy transport through the photosynthetic apparatus have been crucial to expanding our understanding of biological energy conversion. Correlating spectroscopic information to the electronic structure and function in these complex systems remains highly challenging, however. While cryogenic experimental conditions help in improving the effective spectral resolution and sample stability, the observed fine-grained dynamics do not necessarily reflect in vivo functionality. To address this issue, we target the temperature dependence of energy migration in light-harvesting complex 2 of purple bacteria. Temperature- and polarization-controlled two-dimensional electronic spectroscopy reveal rapid exciton immobilization at low temperatures, while intensity-dependent experiments allow identification of transport barriers. We find that exciton trapping, dominating the dynamics at 80 K, becomes negligible above 150 K, implying that observations at cryogenic temperatures do not always directly reflect biological function. We additionally find that considerable care and explicit modeling may be necessary for correct interpretation of multiexciton experiments.</p>}},
  author       = {{Keil, Erika and Malý, Pavel and Cogdell, Richard J. and Hauer, Jürgen and Zigmantas, Donatas and Thyrhaug, Erling}},
  issn         = {{1948-7185}},
  language     = {{eng}},
  month        = {{02}},
  number       = {{8}},
  pages        = {{2313--2320}},
  publisher    = {{The American Chemical Society (ACS)}},
  series       = {{Journal of Physical Chemistry Letters}},
  title        = {{Ultrafast Spectroscopy Reveals Significant Differences in LH2 Exciton Mobility at Cryogenic and Ambient Temperatures}},
  url          = {{http://dx.doi.org/10.1021/acs.jpclett.5c03917}},
  doi          = {{10.1021/acs.jpclett.5c03917}},
  volume       = {{17}},
  year         = {{2026}},
}