Nuclear spin-lattice relaxation in trans-polyacetylene (CH)sub(x). A confined soliton model including nuclear spin flip diffusion

A ''confined soliton model'' in which the solitons move over a small part of the chain is developed. The on-chain nuclei are relaxed directly by contact hyperfine interactions whilst the remainder nuclei relax via nuclear spin flip diffusion. It is found that the proton spin-lattice relaxation data can be rationalized in terms of the fast and confined one-dimensional hopping motion of the soliton whilst that for enriched 13C one requires in addition a much more dominating mechanism that of nuclear spin flip diffusion