THEORETICAL-ANALYSIS OF THE RAMAN-SPECTRA OF PTV AND PFV

In this work, we report experimental Raman and IR results obtained on two different polymers composed of heteroaromatic rings separated by a vinyl group, namely poly(thienylene vinylene) (PTV) and poly(furylene vinylene) (PFV). PTV and PFV exhibit a rather similar behaviour and, in particular, in both cases the observed Raman bands undergo a slight shift when the excitation wavelength is changed from 676.7 to 457.9 nm. By using a dynamical model based on valence force field calculations, we have assigned all IR and Raman modes. In order to obtain a good set of force constants, we started calculations by considering those of polythiophene and, also, we used a model compound such as trans-bis(2-thienyl)ethylene. It was found that the numerical values given for these force constants are consistent with the electronic structure usually assigned for these polymers. © 1990.