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Portrait of Tönu Pullerits; Photo: Kennet Ruona

Tönu Pullerits

Professor

Portrait of Tönu Pullerits; Photo: Kennet Ruona

Before Förster. Initial excitation in photosynthetic light harvesting.

Author

  • Khadga Jung Karki
  • Junsheng Chen
  • Atsunori Sakurai
  • Qi Shi
  • A. Gardiner
  • O Kuhn
  • Richard J Cogdell
  • Tönu Pullerits

Summary, in English

Electronic 2D spectroscopy allows nontrivial quantum effects to be explored in unprecedented detail. Here, we apply recently developed fluorescence detected coherent 2D spectroscopy to study the light harvesting antenna 2 (LH2) of photosynthetic purple bacteria. We report double quantum coherence 2D spectra which show clear cross peaks indicating correlated excitations. Similar results are found for rephasing and nonrephasing signals. Analysis of signal generating quantum pathways leads to the conclusion that, contrary to the currently prevailing physical picture, the two weakly coupled pigment rings of LH2 share the initial electronic excitation leading to quantum mechanical correlation between the two clearly separate absorption bands. These results are general and have consequences for the interpretation of initially created excited states not only in photosynthesis but in all light absorbing systems composed of weakly interacting pigments where the excitation transfer is commonly described by using Förster theory. Being able to spectrally resolve the nonequilibrium dynamics immediately following photoabsorption may provide a glimpse to the systems' transition into the Förster regime.

Department/s

  • Chemical Physics
  • NanoLund: Center for Nanoscience

Publishing year

2019

Language

English

Pages

7923-7928

Publication/Series

Chemical Science

Volume

10

Document type

Journal article

Publisher

Royal Society of Chemistry

Topic

  • Physical Chemistry
  • Atom and Molecular Physics and Optics

Status

Published

ISBN/ISSN/Other

  • ISSN: 2041-6539