ESR STUDIES ON POLYMERS WITH PARTICULAR ELECTRONIC AND MAGNETIC-PROPERTIES

Measurements on insulating and conducting polymers from the polyanilin e (PANI) family and investigations on semiconducting poly(tetrathiaful valenes) (PTTF) have been used for illustration and discussion of some methodical questions of electron spin resonance (ESR). This concerns especially the new possibilities of the recently developed high-resolu tion ESR in the 2 mm wave band. it was applied for the study of the na ture and dynamics of paramagnetic centres (PC) and charge carriers in PANI and PTTF. The rate of the quasi-one-dimensional (1D) intrachain e lectron motion and of the three-dimensional (3D) interchain electron h opping has been estimated separately. In iodine-doped PTTF the maximum electrical conductivity is 10(-4) S.cm-1. It is almost identical with the 3D-conductivity estimated by ESR and shows the typical temperatur e dependence of a semiconductor. The quasi-1D-conductivity is several orders of magnitude higher and shows in its dependence on temperature similarities with a metal. The PANI samples show in the highly doped f orm a maximum conductivity of about 10 S.cm-1 arid relativly small dif ferences between the 1D- and 3D-conductivity, supporting the model of metallic islands.