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Portrait of Tönu Pullerits; Photo: Kennet Ruona

Tönu Pullerits

Professor

Portrait of Tönu Pullerits; Photo: Kennet Ruona

Using fluorescence detected two-dimensional spectroscopy to investigate initial exciton delocalization between coupled chromophores

Author

  • Marco Schröter
  • Tõnu Pullerits
  • Oliver Kühn

Summary, in English

Förster theory describes electronic exciton energy migration in molecular assemblies as an incoherent hopping process between donor and acceptor molecules. The rate is expressed in terms of the overlap integral between donor fluorescence and acceptor absorption spectra. Typical time scales for systems like photosynthetic antennae are on the order of a few picoseconds. Prior to transfer, it is assumed that the initially excited donor molecule has equilibrated with respect to the local environment. However, upon excitation and during the equilibration phase, the state of the system needs to be described by the full density matrix, including coherences between donor and acceptor states. While being intuitively clear, addressing this regime experimentally has been a challenge until the recently reported advances in fluorescence detected two-dimensional spectroscopy. Here, we demonstrate using fourth order perturbation theory the conditions for the presence of donor-acceptor coherence induced cross-peaks at zero waiting time between the first and the second pair of pulses. The approach is illustrated for a heterodimer model which facilitates an analytical solution.

Department/s

  • Chemical Physics
  • NanoLund: Center for Nanoscience

Publishing year

2018

Language

English

Publication/Series

Journal of Chemical Physics

Volume

149

Issue

11

Document type

Journal article

Publisher

American Institute of Physics (AIP)

Topic

  • Physical Chemistry
  • Atom and Molecular Physics and Optics

Status

Published

ISBN/ISSN/Other

  • ISSN: 0021-9606