Pinning of /spl pi/ electrons in polyconjugated systems and frequency dispersion of the R mode (amplitude mode)

Summary form only given. The correlative study of the Raman spectra (recorded in our laboratory) of series of oligomers of several classes of polyconjugated materials shows that the frequency and intensity dispersion of the R mode (amplitude mode) greatly changes in the different classes . This fact reflects the pinning of /spl pi/ electrons within the various chemical groups. This phenomenon is analyzed and its relevance in determining the localisation (confinment) length is discussed.