The interpretation of the infrared and Raman spectra of pristine polypyrrole as 1-d lattice is presented as the result of lattice dynamical calculations. Geometries and vibrational force fields are derived from semiempirical quantum chemical calculations and/or from the optical spectra of oligomers. This paper lays the background information which are used in the second paper, which immediately follows, where the spectra of the conducting polymer are extensively discussed.

A detailed vibrational analysis of the infrared and Raman spectra of doped and pristine polypyrrole is presented. The theory of the effective conjugation coordinate is applied and fully justifies the observed spectra. The information on the structure and properties of this material derived from the proposed analysis are presented and discussed.

Electronic and structural properties of polyparaphenylenevinylene from the vibrational spectra J. Chem. Phys. 95, 3198 (1991); 10.1063/1.460876Optical spectra of molecular crystals: The effect of exciton band structure on spectra and linewidths

The infrared and Raman spectra of oligomeric model molecules of polyparaphenylenevinylene (PPV) and of the polymer in the pristine state, and the infrared spectra of doped or photoexcited PPV are analyzed in terms of the theory of the effective conjugation coordinate (ECC). It is shown that all the spectroscopic observations (frequencies and intensities) are accounted for by ECC theory which shows that most of the observed features are due to the delocalization of π electrons. Measurements of the lower limit of the effective conjugation length and of the molecular chain length are made and the structural relevance of such concepts are discussed in terms of the conformation of the oligomeric or polymeric chain. Evidence is found that the charge carrier produces ‘‘quinoid’’ type defects, hence fully coplanar.

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