ABSORPTION-SPECTRA OF THE ANIONS OF PHENYLENEVINYLENE OLIGOMERS AND POLYMER

The absorption spectra of chemically prepared mono- and di-valent anions of phenylenevinylene oligomers and polymer are reported. The spectra consist of three features, each subject to vibronic splitting. Retaining their general character, the spectra shift towards lower energies with increasing chain length akin to the shift of the neutral molecule absorption bands. The spectrum of the monovalent polymer anion resembles the photoinduced absorption spectrum of polyphenylenevinylene suggesting that the latter is due to a monovalent rather than a divalent species. It is argued that no transitions among localized (polaron) and delocalized (band) states need to be invoked to interpret oligomer as well as polymer anion spectra.