| Summary: | The work contained in this thesis regards both surface related techniques, and the use of the muon as a hydrogen analogue in the investigation of fast charge-exchange cycles. In the period 1997-1999, a pulsed low-energy muSR facility was developed, based on rare-gas moderation of a conventional pulsed muon beam. Various parameters of the technique were investigated, including the first direct measurements of the muon energy distribution. A full account is given of the sample-handling chamber designed and built for the adaptation of this source into a full user facility. Using conventional muon beams, muonium interactions with the surface of a fine silica powder are studied, via the addition of condensed rare gases (He, Ar, Kr, Xe) in sub-monolayer coverages. We prove for the first time that at least 60% of the muonium yield is formed at the surface of the powder grains, and discount the possibility that bulk formed muonium is dissociated at the surface by ionised gas atoms. An additional mechanism for muonium formation, based on atomic recoil, is also proposed. Muon spin-rotation measurements on silicon show the onset of a substantial paramagnetic shift from the muon Larmor frequency. The inferred fraction of the time spent as neutral paramagnetic muonium is close to unity above 600 K, so the capture rate of conduction electrons greatly exceeds the effective ionisation rate. Configuration-coordinate models for the interplay between site and charge state are described and developed. A number of non-magnetic semimetals and metals are found to exhibit significant muon spin relaxation, which suggests a form of Korringa relaxation, also linked to conduction electron encounter at an interstitial site. The relationship between relaxation rate and muon Knight shift is investigated; we look briefly at the nature of defect screening; and consider the similarities with electronic activity seen in semiconductors at high temperatures.
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