Fluorescence-Detected Wavepacket Interferometry Reveals Time-Varying Exciton Relaxation Pathways in Single Light-Harvesting Complexes

Title data

Wiesneth, Stephan ; Recknagel, Paul ; Gardiner, Alastair T. ; Cogdell, Richard J. ; Hildner, Richard ; Köhler, Jürgen:
Fluorescence-Detected Wavepacket Interferometry Reveals Time-Varying Exciton Relaxation Pathways in Single Light-Harvesting Complexes.
In: Journal of the American Chemical Society. (21 October 2025) .
ISSN 1520-5126
DOI: https://doi.org/10.1021/jacs.5c12416

Official URL:

Abstract in another language

Photosynthesis relies on efficient energy relaxation within the excited-state manifold of pigment–protein complexes. Since the protein scaffold is rather flexible, the resulting energetic and structural disorder gives rise to a complex excited-state energy level structure that fluctuates on all time scales. Although the impact of such fluctuations on relaxation processes is known, the precise exciton states involved in relaxation as well as the nature of the vibrational modes driving relaxation are under debate. Here, single pigment–protein complexes from a photosynthetic purple bacterium are excited with two identical ultrashort phase-locked pulses, producing two exciton wave packets that can interfere. This leads to a modulation of the emission intensity as a function of the delay time between the pulses that fades out within about ≈100 fs due to fluctuating environments on those time scales. For several single complexes, we find variations in the interference patterns on a time scale of several tens of seconds that reveal fluctuations in the energy relaxation pathways toward the lowest-energy exciton states. This relaxation is driven by temporal variations in the coupling between electronic excitations and low-frequency vibrational modes.

Further data

Item Type:	Article in a journal
Refereed:	Yes
Institutions of the University:	Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics > Chair Experimental Physics IX - Spectroscopy of Soft Matter > Chair Experimental Physics IX - Spectroscopy of Soft Matter - Univ.-Prof. Dr. Jürgen Köhler
Result of work at the UBT:	Yes
DDC Subjects:	500 Science > 530 Physics
Date Deposited:	24 Oct 2025 09:51
Last Modified:	24 Oct 2025 09:51
URI:	https://eref.uni-bayreuth.de/id/eprint/95002