Muonium states in Ag2O studied by level crossing and RF resonance

As part of a survey of muonium states in insulating and semiconducting oxides, we have identified three different muonium states in silver oxide, observable over different temperature ranges. All of the states have hyperfine constants much lower than "vacuum" muonium and significant dipolar contributions, not unlike the bond-centred muonium in tetrahedral semiconductors. Level crossing resonance measurements give the hyperfine constants for the possible states. Analysis of the relaxation rates as a function of temperature shows that muonium undergoes thermally activated conversion to states with progressively lower hyperfine coupling, and ultimately ionises above 200 K. RF resonance also confirms both the isotropic and dipolar parts of the hyperfine constants of two of the states. (c) 2005 Elsevier B.V. All rights reserved.