Some characteristics of muon states in silicon

Recent results of muon spin rotation studies on silicon are discussed, Special attention is paid to the temperature and doping dependences of the formation probabilities and relaxation rates of the observed muon states. It is argued that normal muonium (Mu) and anomalous muonium (Mu*) are two completely different states with respect to physical and chemical properties. Mu* is a localized state, whereas evidence suggests that Mu diffuses through the silicon lattice.