Abstract
In this paper, we present a complete vibrational study of polyparaphenylene-vinylene (PPV) using Resonance Raman Scattering (RRS) and Infrared spectroscopy. A dynamical model based on valence force-field calculations has been built in order to assign the observed Raman and IR vibrational modes, and trans-stilbene served as a model compound to establish a good set of force constants for the neutral polymer. Upon doping with FeCl 3 , the Raman spectra exhibit rather strong modifications. In order to obtain a good agreement with experimental data of doped PPV, a new set of force constants is needed which supports the existence of a quinoid-like structure along the PPV chains. © 1989.