Recent progress in electron probe microanalysis

Electron probe microanalysis (EPMA) is a fairly mature analytical technique which has been widely used in the fields of geochemistry and materials science since the early 1960s. The 1980s and early 1990s or so have seen dramatic improvements, both theoretical and experimental, in the accuracy with which the concentrations of light elements such as oxygen can be measured by EPMA. This has coincided with a resurgence of interest in mixed-valence oxides which was stimulated by the discovery of high temperature superconductivity, and EPMA is now a vital tool for condensed matter physicists working in this field. Stoichiometric characterization is particularly important in the area of thin films, and a great deal of work has been devoted to modifying existing EPMA correction procedures in order to perform analyses of thin film or layered specimens. The present article reviews the progress that has been made from a physicist's perspective, paying attention to the levels of accuracy and precision which are now attainable, and to the advantages and disadvantages of EPMA in relation to other analytical techniques.