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Updated: Jan 10, 2026
06:08
Time-resolved Photophysical Characterization of Triplet-harvesting Organic Compounds at an Oxygen-free Environment Using an iCCD Camera
Published on: December 27, 2018
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Excimer and non-photochemical quenching in LHCII.
Jian-Wei Zou1, Dan-Hong Li1,2, Rong-Yao Gao3
1College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, China.
The Journal of Chemical Physics
|November 21, 2025
Summary
Excess energy in photosynthesis is safely dissipated by light-harvesting complex II (LHCII) via non-photochemical quenching (NPQ). This study reveals chlorophyll excimers are key intermediates in LHCII, facilitating safe energy dissipation and preventing photodamage.
Area of Science:
- Photosynthesis research
- Photophysics of light-harvesting complexes
- Molecular mechanisms of energy dissipation
Background:
- Light-harvesting complex II (LHCII) captures and dissipates photosynthetic energy.
- Non-photochemical quenching (NPQ) safely dissipates excess excitation energy, preventing photodamage.
- Chlorophyll excimers are proposed photophysical intermediates in LHCII for quenching.
Purpose of the Study:
- Investigate the mechanism of chlorophyll singlet excitation (1Chl*) deactivation in LHCII.
- Determine the role of chlorophyll excimers in non-photochemical quenching (NPQ).
- Differentiate energy deactivation pathways in quenched (Q-F730) and non-quenched (U-F680) LHCII.
Main Methods:
- Ultrafast transient absorption spectroscopy.
- Broadband two-dimensional electronic spectroscopy.
- Comparative analysis of quenched and non-quenched LHCII preparations.
Main Results:
- Lower photoproduction of carotenoid (Car) triplet excitation in Q-F730 compared to U-F680.
- Intersystem crossing is unlikely the primary deactivation channel for 1Chl*.
- Spectroscopic evidence supports 1Chl* deactivation via chlorophyll excimer formation and a Chl charge transfer state.
Conclusions:
- Chlorophyll excimers are directly linked to chlorophyll singlet excitation in LHCII.
- Excimer formation is a significant pathway for 1Chl* deactivation during NPQ.
- This research elucidates the mechanistic basis of NPQ in photosynthetic light-harvesting complexes.
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