Positive muons injected into solid ${\mathrm{C}}_{70}$ form a vacuumlike muonium (Mu) state with a 25% probability. This state is attributed to muons inside the ${\mathrm{C}}_{70}$ cage (${\mathrm{C}}_{70}$:Mu). In addition, three different types of muonated free radicals, distinguishable by their hyperfine coupling constants, are observed. These radicals are attributed to muonium addition on the outside of the ${\mathrm{C}}_{70}$ molecule at different sites. The hyperfine parameters of these radicals reflect the different degrees of delocalization of the unpaired electron. The temperature dependence of the depolarization rates yields information on the dynamics of the ${\mathrm{C}}_{70}$ molecules.

• Received 9 November 1992

DOI:https://doi.org/10.1103/PhysRevB.47.10923