Spin dynamics in K-doped polyacetylene

The proton spin-lattice relaxation time (T1) of a stretched K-doped polyacetylene sample has been measured as a function of the frequency. The data are in agreement with the relaxation due to a pseudo-1D diffusion of the charge carrier spins, with an intrachain spin diffusion rate D∥ ≈ 3 × 1016 rad s−1 and a very high anisotropy D∥D⊥ ∼ 105. This leads to a microscopic intrachain conductivity, σ∥ ≈ 1 × 104 S cm−1, consistent with the macroscopic dc value, σDC = 1.1. × 103 S cm−1. An alternative interpretation of the data in terms nuclear relaxation due to fixed electronic spins is not excluded.