Dynamics of spin excitations in conducting poly(tetrathiafulvalene)

Summary form only given. High resolution 2-mm waveband EPR technique combined with the steady-state saturation, saturation transfer and spin label methods was used for comparative investigating at wide temperature range magnetic, relaxation and dynamic properties of localized and mobile polarons in poly(tetrathiafulvalene) semiconductors whose TTF units, are linked via phenyl or tetrahydroanthracene groups. Relaxation and diffusion rates of polarons in the samples were determined by steady-state saturation method. The intensity and activation energy of anisotropic slow librations of polymer chains, were found by saturation transfer method to depend an the structure and doping level of the sample. The charge transfer is realized in an undoped polymer in the frames of the Kivelson theory. The interchain spin hopping was shown to correlate in a slightly doped polymer with torsion librations of its chains and to be in a good agreement either with the variable range hopping (at low temperatures) or with the activation (at higher temperatures) charge transport mechanisms. This evidences the formation of complex quasi-particles, namely molecular polarons covered by a lattice polarization in the latter case. The conformation of the polymer was shown to be more planar at substituting phenyl groups for tetrahydroanthracene ones.