THEORETICAL INTERPRETATION OF THE ELECTROABSORPTION SPECTRA OF POLYACENE CRYSTALS .1. ROLE OF FRENKEL STATES

The recently proposed two-dimensional model of the coupling between th e Frenkel and charge transfer (CT) excitations of a molecular crystal, successfully applied for the calculation of the electroabsorption (EA ) spectra of polyacenes [Petelenz et al., J. Chem. Phys. 105, 4427 (19 96)], is applied to probe the influence of different intramolecular ex cited states on the EA signal in the CT energy range. The study highli ghts the preeminent role of Frenkel excitons that are energetically cl ose to the CT manifold, even if they are inactive in conventional abso rption spectroscopy. The high-energy intense excitons are found to hav e a lesser effect. The study suggests EA spectroscopy as a potential t ool to detect and locate some of the absorption-inactive intramolecula r excitations. (C) 1997 American Institute of Physics.