RAMAN-STUDY OF ALPHA-OLIGOTHIOPHENES AND MODEL COMPOUNDS OF POLY(THIENYLENE VINYLENE)

In this work, we present a complete vibrational study of a series of t he alpha-coupled oligothiophenes. Both experimental and theoretical in vestigations have been carried out by using spectroscopic techniques s uch as Raman Scattering and infrared absorption and analysed as a func tion of the oligomer length. Detailed calculations lead to a clear ass ignment of the vibrational modes in all compounds and to determination of a main force constants associated with the different chemical bond s. In a similar way, Raman studies of model compounds of poly(thienyle ne vinylene) (PTV), such as 1-2 bis (thienylene) vinylene (2TV) and 2- 5 bis (2-thienyl vinyl) thiophene (3T2V) have been carried out. The tw o modes associated with the C=C stretching of the vinyl group and the thiophene ring respectively are found to slightly depend on the length of the compounds.