Noble gases in copper

Abstract

This thesis reviews five publications where interactions between a gas impurity and copper metal are studied both experimentally and theoretically. The experimental part includes thermal desorption measurements where a copper sample is bombarded and heated while monitoring releasing gas with a mass spectrometer. This yields usually spectra where every peak represents a different binding state of the impurity atom. New analysing methods, based on kinetic equations have been developed to extract information from these spectra. All the developed methods are tested with measured spectra in various cases. The new methods can also be applied to diffusion phenomena. Thermal desorption spectroscopy needs support from theory, since usually the origin of the peaks cannot be explained purely through peak analysis. Examples are multiply filled vacancies, vacancy clusters and heavier gas-impurities, such as argon or neon. The effective medium theory has been used to study helium, neon and argon in copper. For helium excellent agreement with the experimental results was obtained. In the cases of neon and argon equally clear theoretical interpretation of all peaks of the spectrum could not be obtained.