Erlangen 2018 – scientific programme
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MO: Fachverband Molekülphysik
MO 13: Posters 1: Ultrafast Spectroscopy
MO 13.12: Poster
Tuesday, March 6, 2018, 16:15–18:15, Orangerie
Excitonic Coupling and Energy Transfer in the LH2 Complex of Allochromatium Vinosum — •Marco Schröter1, Marcelo Alcocer2, Oliver Kühn1, and Donatas Zigmantas2 — 1Institut für Physik, Universität Rostock, Albert-Einstein-Str. 23-24, 18059 Rostock, Germany — 2Chemical Physics, Lund University, Box 124, 22100 Lund, Sweden
Bacterial photosynthesis is one of the most adaptable and robust energy harvesting processes in nature, with light-harvesting complexes playing a crucial role. The peripheral light-harvesting complex (LH2) of the purple bacterium Allochromatium vinosum is particularly distinct as it shows a double peak structure in the B800 absorption band. Two hypotheses concerning the origin of this splitting have been proposed; either two distinct B800 bacteriochlorophyll site energies [1], or an excitonic dimerization of bacteriochlorophylls within the B800 ring [2]. Through the use of two-dimensional electronic spectroscopy, we present unambiguous evidence that the peak splitting is due to the latter. Furthermore, we identify and characterize all energy transfer pathways within this complex by using a refined global fitting procedure [3]. Our approach demonstrates how the combination of two-dimensional spectral resolution and self-consistent fitting allows for the extraction of information on light-harvesting processes, which would otherwise be inaccessible due to signal congestion.
[1] D. M. Niedzwiedzki et al., Biochim. Biophys. Acta 1817, 1576 (2012) [2] A. Löhner et al., Photosynth. Res. 123, 23 (2015) [3] J. Dostal et al., J. Chem. Phys. 145, 124312 (2016)