The disappearance of C60+ electron paramagnetic resonance centres during the intercalation of polycrystalline C60 with Rb was described as being a 2-stage process; with inter-grain and intra-grain penetration of Rb into the C60 sample. This led to the quenching of C60+ hole states via a recombination process. It was noted that there was a similarity of the kinetics, of alkali inter-grain and intra-grain penetration into powdered C60, to the kinetics of O penetration through C60 films; associated with the generation of C60+ centres.

C60+ Defect Centers: Effect of Rubidium Intercalation into C60 Studied by EPR. W.Kempiński, L.Piekara-Sady, E.A.Katz, A.I.Shames, S.Shtutina: Solid State Communications, 2000, 114[3], 173-6