Quantum lattice motion and optical properties of polyenes

Abstract Short polyenes exhibit optical properties similar to those of nondegenerate polymers. The broad subgap absorption tail, the vibronic features in the absorption as well as in the luminescence spectra together with the large Stokes' shift are evidence of nonlinear quantum lattice fluctuations. We have carried out a detailed and careful study of those effects in the context of the SSH model. Implications of this on the optical properties of conjugated polymers are discussed. Another interesting theoretical result is the dispersion of the resonant Raman-line profile due to those intrinsic lattice fluctuations. This contrasts with the interpretation of the same effect in terms of sample inhomogeneity.