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 electro chemically alkali metals (lithium and sodium) intercalated poly(paraphenyle ne) was investigated as a function of the intercalant content. Two differen t ESR signals were successively observed. The one at the intermediate dopin g level is related to the formation of paramagnetic polarons, while the sec ond one, for heavily doped samples, can be attributed to conduction electro ns. As a matter of fact, study of the temperature dependence of these ESR s ignals confirms the metallic character of the compounds intercalated to sat uration, contrary to the intermediate doped PPP, where the ESR spectra are characteristic of partly localized paramagnetic species. The Dyson effect w as observed for highly doped lithium-PPP compounds pressed in pellets. (C) 1999 Elsevier Science Ltd. All rights reserved.