NMR evidence for heterogeneous disorder and quasi-1D metallic state in polyaniline CSA

Spin dynamics has been investigated by NMR techniques in highly conducting CSA doped polyaniline (PANI-CSA). Proton nuclear relaxation times have been measured as a function of frequency and temperature. Effective intra and interchain diffusion rates are determined in the frame of a quasi-1D diffusion model. The results are analyzed in the frame of an heterogeneous disorder with metallic regions (crystalline or well-ordered parts), linked by poorly conducting electronically isolated chains (amorphous parts). Spin carriers execute a strongly anisotropic quasi-1D motion in both types of region. Hopping motion in disordered regions appears as the limiting mechanism in the conduction process.