MUON STUDIES OF SPIN DYNAMICS IN POLYANILINE

The muon is a valuable probe of spin excitations in polymers, as the m uon implantation process itself generates a lest excitation whose dyna mical properties can be studied via the evolution of the muon spin pol arisation. We report here studies on undoped polyaniline in its emeral dine base form (PANI:EB). Characteristic field dependences and cutoff frequencies for the muon spin relaxation are observed which are relate d to the spin diffusion. One-dimensional diffusion is seen at low temp eratures and at short probe times. The on chain diffusion is observed to have a weak metallic temperature dependence whereas the interchain diffusion is strongly activated and phenyl ring rotations are seen to have an important effect on the diffusion processes.