Electron spin resonance in lithium and sodium electrochemically intercalated poly(paraphenylene)

The evolution of the ESR characteristics (Delta H-pp, g and A/B) of electrochemically alkali metals (lithium and sodium) intercalated poly(paraphenylene) was investigated as a function of the intercalant content. Two different ESR signals were successively observed. The one at the intermediate doping level is related to the formation of paramagnetic polarons, while the second one, for heavily doped samples, can be attributed to conduction electrons. As a matter of fact, study of the temperature dependence of these ESR signals confirms the metallic character of the compounds intercalated to saturation, contrary to the intermediate doped PPP, where the ESR spectra are characteristic of partly localized paramagnetic species. The Dyson effect was observed for highly doped lithium-PPP compounds pressed in pellets. (C) 1999 Elsevier Science Ltd. All rights reserved.