Modelling isolated hydrogen impurity in Lu2O3 with muonium spectroscopy

We identified in this experiment two muon configurations in Lu₂O₃, the oxygen-bound (O-Mu⁺) ground state and a metastable (energy barrier 0.7(3) eV) atom-like excited state. These configurations are partially not formed immediately after implantation but somewhat delayed due to the requirement of a lattice rearrangement around the muon. These rearrangement processes occur on a timescale of ns to µs and are thus observable in µSR experiments. A special role plays a fairly long-lived (ns to µs) transition state as an intermediate step in the reaction process.