We have measured the longitudinal spin-relaxation functions of positive muons injected into trans-${\left(\mathrm{CH}\right)}_x$ at various temperatures and external fields. They showed non-single-exponential functions and were fitted by a model which takes into account both the on-chain diffusion and the disappearance of the muon-produced soliton. It was found that the on-chain diffusion rate $D_{\parallel }$ is almost constant from 29 to 290 K, while the disappearance rate $D_3$ slightly increases with temperature.

• Received 11 June 1985

DOI:https://doi.org/10.1103/PhysRevLett.55.2009