ELECTRONIC-STRUCTURE OF EMERALDINE AND PERNIGRANILINE BASE - A JOINT THEORETICAL AND EXPERIMENTAL-STUDY

The electronic structure of the emeraldine and pernigraniline base for ms of polyaniline is revisited with a combined experimental and theore tical approach. On the one hand, high-resolution valence band photoele ctron spectra are presented. High-quality electronic structural inform ation is obtained due to the use of chemically pure and well-defined m aterials, which could be studied for the first time with a high-resolu tion photoelectron spectroscopy facility. On the other hand, the elect ronic band structures and the density of valence states spectra associ ated with these polymers are calculated by means of the pseudopotentia l valence effective Hamiltonian (VEH) technique. The excellent agreeme nt observed for the first time between the experimental and theoretica l results obtained on these polymers clearly validates the description of the emeraldine and pernigraniline valence band electronic structur e within the VEH formalism and allows us to evaluate the ionization po tential of both polymers. (C) 1998 Elsevier Science S.A. All rights re served.