SPIN DYNAMICS STUDY IN POLYANILINE - MACROSCOPIC AND MICROSCOPIC TRANSPORT PROPERTY RELATIONSHIP

Proton spin lattice relaxation times T1 have been measured in the freq uency range 7-95 MHZ on a set of unstretched and stretched polyaniline films, together with d.c. conductivity. A highly anisotropic quasi 1D spin diffusion is evidenced in all the samples. It is shown that whil e stretching increases parallel d.c. conductivity, it favours intercha in hoppings at the microscopic scale. These results are interpreted in a coherent picture that links the macroscopic transport properties to the microscopic ones. In particular, d.c. conductivity anisotropy is shown to be of geometrical nature when the microscopic transport aniso tropy is very high. It is also concluded that the carrier mean free pa th is not consistent with metallic conductivity.