Analysis of resonant Raman scattering spectra of fully oriented undoped and iodine-dopedtrans-polyacetylene: Experiments and theory

Polarized resonant Raman spectra of oriented trans-polyacetylene taken at different excitation wavelengths (${\lambda }_L$=647.1 and 457.9 nm) are presented for undoped and iodine-doped samples together with theoretical calculations based on distributions of conjugated segments. A detailed analysis of the band shapes and peak positions of the Raman bands in the two different cases reveals important differences, in agreement with a modification upon doping of the morphology of the polymer. The proposed model turns out to be appropriate for interpreting all the experimental data.