MAGNETIC-RESONANCE STUDIES OF HEAVILY-DOPED POLYACETYLENE

H-1-NMR relaxation rate T1(-1) and ESR absorption of heavily doped Shi rakawa polyacetylene were measured to get microscopic information of i ts metallic state. Experimental results suggest that non-metallic rela xation mechanism such as molecular motion of polyacetylene chains larg ely contributes to T1(-1) in addition to intrinsic metallic relaxation mechanism. In the Br-doped sample, however, the temperature dependenc e of T1(-1) changed gradually from non-metallic dependence to metallic one with time passing. In contrast with the Br-doped sample, no chang e in the temperature dependence of T1(-1) was not seen in the K-doped sample, and kept showing non-metallic dependence. An addition and/or a substitution reaction of bromine to polyacetylene chain is considered to suppress extrinsic relaxation mechanism.