Theoretical analysis of absorption and raman spectra of polyacetyle-type copolymers

Summary form only given. Diblock polyacetylene-polynorbornene copolymers with controlled conjugated sequences have been prepared in both thin films or solution. We report here a theoretical analysis of the absorption and Raman spectra recorded from the different samples in which the conjugated sequences are varied from long to short. In all cases, the same bimodal distribution is used in order to calculate both absorption and Raman spectra whose results are in good agreement with experimental data. In particular, we are able to explain the well resolved structures observed in the spectra from samples in solution characterized by short sequences. The distributions we have used is centered on /spl tilde/ 5 and 10 C = C respectively, with a low weight on the latter one, leading to an overall asymmetric profile. On the other hand, the same analysis applied to the absorption and Raman spectra with long controlled sequences (for example, N/sub C = C/ = 40 or 100), leads to a bimodal distribution centered on 8 and 40 C = C.