Chapter 8: Dynamics of Muonium Diffusion, Site Changes, and Charge-State Transitions

Abstract

This chapter discusses the dynamics of muonium (Mu) diffusion, site changes, and charge-state transitions. Mu is formed when positive muons are implanted into a target material—for example, a semiconductor. The states formed by the implanted muons are investigated in the chapter along with their static properties. Because of the large mass difference, quantum effects—such as zero-point energy and tunneling—can be much more important for Mu than for isolated hydrogen (H). The Mu charge-cycle results are relevant to H motion and suggest that diffusion could occur as repeatedly interrupted motion even without formation and dissociation of an H-impurity complex. The interstitial location of isolated H and its diffusive properties are directly related to its charge state. The reactivity of H with other impurities is significantly impacted by charge states and diffusive motion. The results for Mu transition dynamics apply qualitatively to the analogous isolated H impurities; thus, the experiments presented in the chapter yield information on hydrogen states that are extremely difficult to directly investigate.