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2007-06-06 - Article/Dans un journal avec peer-review - Anglais - 11 page(s)

Spano F.C., Meskers S.C.J., Hennebicq E., Beljonne David , "Probing Excitation Delocalization in Supramolecular Chiral Stacks by Means of Circularly Polarized Light: Experiment and Modeling" in Journal of the American Chemical Society, 129, 22, 7044-7054

  • Edition : American Chemical Society, Washington (DC)
  • Codes CREF : Chimie quantique (DI1321), Optique (DI1250)
  • Unités de recherche UMONS : Chimie des matériaux nouveaux (S817)
  • Instituts UMONS : Institut de Recherche en Science et Ingénierie des Matériaux (Matériaux)
Texte intégral :

Abstract(s) :

(Anglais) Photoexcitations in helical aggregates of a functionalized, chiral oligophenylenevinylene (MOPV) are described going beyond the Born-Oppenheimer approximation, in the form of dressed (polaronic) Frenkel excitons. This allows for accurate modeling of the experimentally observed wavelength dependence of the circular polarization in fluorescence, which directly probes the non-adiabatic nature of the electron-vibration (EV) coupling in this system. The fluorescence photon is emitted from a nuclear geometry in which one MOPV and its two nearest neighbors have a nuclear equilibrium that differs appreciably from the ground state due to the presence of the excited state. The absorption and emission band shape and the circular dichroism are consistent with a coherence range of the emitting excitation of approximately two neighboring molecules. Random fluctuations in the zero-order excited-state energy of the MOPVs (disorder) limit the exciton delocalization and can be described by a Gaussian distribution of energies with a width s = 0.12 eV and a spatial correlation length l0 ˜ 5 molecules. We find that disorder and EV coupling act synergistically in localizing the emitting exciton to a single MOPV in the aggregate with 95% probability.

Notes :
  • (Anglais) Publié en ligne le 12 mai 2007
Identifiants :
  • DOI : 10.1021/ja067321g