Electronic structure of emeraldine and pernigraniline base: a joint theoretical and experimental study

The electronic structure of the emeraldine and pernigraniline base forms of polyaniline is revisited with a combined experimental and theoretical approach. On the one hand, high-resolution valence band photoelectron spectra are presented. High-quality electronic structural information is obtained due to the use of chemically pure and well-defined materials, which could be studied for the first time with a high-resolution photoelectron spectroscopy facility. On the other hand, the electronic band structures and the density of valence states spectra associated with these polymers are calculated by means of the pseudopotential valence effective Hamiltonian (VEH) technique. The excellent agreement observed for the first time between the experimental and theoretical results obtained on these polymers clearly validates the description of the emeraldine and pernigraniline valence band electronic structure within the VEH formalism and allows us to evaluate the ionization potential of both polymers. (C) 1998 Elsevier Science S.A. All rights reserved.