COMPARISON OF THE VIBRATIONAL PROPERTIES OF POLYTHIOPHENE AND POLYALKYLTHIOPHENES

In this paper, we present a study of vibrational properties of conducting polymers containing thiophene rings : polythiophene and polyalkylthiophenes. The spectrocopic studies include Resonance Raman Scattering (RRS) and Fourier Transformed InfraRed absorption (FTIR), that we applied to the polymers mentionned above and to some thiophene oligomers. Results are interpreted by performing dynamical calculations based on a valence force field model. With the oligomer approach, the force constants are less numerous than the experimental frequencies and the results for our assignment much more reliable. The calculations provide a better understanding of Raman and infrared modes, leading to a clear comparaison of the electronic and vibrational properties of neutral polythiophene, polymethylthiophene and polyoctylthiophene.