Metallic temperature dependence of resistivity in heavily doped polyacetylene by NMR

1H-NMR spin-lattice relaxation rate T1−1 of heavily doped polyacetylene was measured in an attempt to deduce the intrinsic resistivity of its metallic phase. Against our intention, in all of the samples a metallic behavior in the T1−1 expected for a quasi-one-dimensional metal was not found for some period after doping, and it was revealed that those T1−1ʹs were governed by a relaxation mechanism due to residual Curie spins. In the bromine-doped sample, however, a change in the temperature dependence of T1−1 from the non-metallic behavior to the metallic one was found as time passed. It was confirmed that this change was caused by the partial substitution of hydrogen atoms by bromine atoms in the polyacetylene chain. We succeeded in deducing the temperature dependence of intrinsic resistivity for metallic polyacetylene from the data of T1−1.