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Portrait of Tönu Pullerits; Photo: Kennet Ruona

Tönu Pullerits


Portrait of Tönu Pullerits; Photo: Kennet Ruona

Fluorescence polarization measures energy funneling in single light-harvesting antennas-LH2 vs conjugated polymers.


  • Rafael Camacho Dejay
  • Sumera Tubasum
  • June Southall
  • Richard J Cogdell
  • Giuseppe Sforazzini
  • Harry L Anderson
  • Tönu Pullerits
  • Ivan Scheblykin

Summary, in English

Numerous approaches have been proposed to mimic natural photosynthesis using artificial antenna systems, such as conjugated polymers (CPs), dendrimers, and J-aggregates. As a result, there is a need to characterize and compare the excitation energy transfer (EET) properties of various natural and artificial antennas. Here we experimentally show that EET in single antennas can be characterized by 2D polarization imaging using the single funnel approximation. This methodology addresses the ability of an individual antenna to transfer its absorbed energy towards a single pool of emissive states, using a single parameter called energy funneling efficiency (ε). We studied individual peripheral antennas of purple bacteria (LH2) and single CP chains of 20 nm length. As expected from a perfect antenna, LH2s showed funneling efficiencies close to unity. In contrast, CPs showed lower average funneling efficiencies, greatly varying from molecule to molecule. Cyclodextrin insulation of the conjugated backbone improves EET, increasing the fraction of CPs possessing ε = 1. Comparison between LH2s and CPs shows the importance of the protection systems and the protein scaffold of LH2, which keep the chromophores in functional form and at such geometrical arrangement that ensures excellent EET.


  • Chemical Physics
  • NanoLund: Center for Nanoscience

Publishing year





Scientific Reports



Document type

Journal article


Nature Publishing Group


  • Atom and Molecular Physics and Optics
  • Physical Chemistry




  • ISSN: 2045-2322