Abstract
We have investigated the experimental x-ray and far-infrared responses of three polythiophenes synthesized from a thiophene, alpha-bithiophene and alpha-quaterthiophene monomer. The x-ray data show that the crystallinity of the different polythiophene samples depends on the synthesis conditions. An excellent correlation between the crystallinity of polythiophenes and their far-infrared signatures is demonstrated. In addition, the assignment of the far-infrared phonon modes in polythiophenes is given by a direct comparison with its oligomers. In particular, the ring libration inside the polymeric chain, directly involved in the electron-phonon coupling, is assigned.