Electron probe microanalyzer with field emission gun

点击翻译按钮获取中文摘要

The electron probe microanalyzer (EPMA) is an indispensable instrument in the investigation of solid matter, when precise element distributions with high spatial resolution down to the sub-micrometer range and exact chemical quantifications of the element contents and detection limits down to the lower 10 µg/g range are required. Electron microprobe analysis is thus an important component of quantitative micron-scaled analysis not only in geoscientific research, but also in materials research in general. At the Geowissenschaftliche Zentrum of the University of Göttingen, the microprobe is used by seveal working groups in combination with a large number of other elemental and isotopical analytical methods:(a) The EPMA methodology is indispensable for obtaining very precise results in thermo-barometry. Intensive parameters such as temperature, pressure or oxygen fugacity can be determined more accurately in suitable phase equilibrium systems of mineral reactions than with many other analytical methods. In particular, we will continue to apply and expand "single-phase thermometers" in the coming years. (b) In order to determine geological time rates from non-equilibrated phase systems, the use of a field emission cathode opens up new possibilities for the analysis of shorter time scales or slow diffusion rates of elements for selected mineral reactions. This work helps to understand time-dependent processes, for example in magmatic systems. Experiments will determine diffusion rates in selected melt or solid state systems.(c) The exact elucidation of some redox-sensitive processes of cosmochemical processes has so far failed due to the low lateral resolution of conventional electron beam technology. Here the field emission cathode will contribute to better results.(d) We use the chemical composition of certain minerals and their parageneses to derive their provenances in sedimentary systems. This allows to reconstruct global geodynamic processes.(e) The device is used in archaeometric research: The EPMA is an essential analytical instrument for the analysis of historical glass, as well as for archaeometallurgical process reconstruction.(f) Geological archives are another focus of current and future research projects. Varying elemental conditions of calcifying marine organisms serve as climate archives and can map temperature changes or changing duration of seaice cover. With the applied electron microprobe with field emission source we will achieve an improved spatial resolution of the quantitative micro-scale analysis. The equipment with sensitive analyzer crystals will lead to more precise measurement results and better detectability.