EXCITONIC EFFECTS IN THIOPHENE OLIGOMERS

Excitonic interactions in conjugated chains are studied by analysing t he optical and vibrational properties of unsubstituted thiophene oligo mers with different supramolecular organization. Single quasi-planar m olecules, electronically decoupled in the solid state, have been obtai ned by inclusion of the thiophene oligomers in perhydrotriphenylene. R esonant Raman scattering shows that the strong spectral changes which occur upon molecular aggregation can be explained only by electronic e xcited state interactions, in rather good agreement with the predictio n of the molecular exciton model.