Quantum diffusion of the muonium (Mu) atom has been studied in solid nitrogen crystals using the technique of Mu spin relaxation. At low temperatures the results are inconsistent with diffusion models using a single correlation time ${\mathrm{\tau }}_{\mathit{c}}$; instead, the muon polarization exhibits two-component relaxation, which is taken as evidence for the intrinsic inhomogeneity of Mu dynamics in a spatially inhomogeneous crystal. Conventional trapping mechanisms are shown to be ineffective at low temperatures in insulators. © 1996 The American Physical Society.

• Received 16 November 1995

DOI:https://doi.org/10.1103/PhysRevB.53.11300