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MI: Fachverband Mikrosonden

MI 1: Electron Probe Microanalysis

MI 1.1: Invited Talk

Tuesday, March 8, 2016, 09:30–10:15, H5

Extending the frontiers of high-resolved measurements with a Field Emission Microprobe — Silvia Richter and •Philippe Pinard — RWTH Aachen, Germany

Field emission (FE) electron microprobes have pushed the boundaries of electron probe microanalysis (EPMA) by offering new ways to characterize smaller features. As with conventional microprobes, analytical conditions should be properly selected for an accurate and precise quantification. The challenge is to optimize these parameters to obtain the best spatial resolution. Furthermore, instrumental parameters such as the focusing capability, beam stability and stage reproducibility, influence high resolution acquisitions. Carbon contamination has to be considered as well. Higher spatial resolution can be achieved by lowering the beam energy. But this can result in quantification problems of soft x-ray lines, i.e. Lα lines of the transition elements, where the electronic structure of the atoms and chemical bonding play a significant role in the generation and absorption of x-rays. Alternative solutions would be the use of Ll lines or using a small overvoltage ratio. Using the same overvoltage ratio for all measured x-ray lines requires a good reproducibility of the beam focus and -position, if the beam energy is changed. Defocus or shift effects can be corrected by a probe tracking function. However, changing the beam energy influences brightness and contrast of the images used for probe tracking which provides new challenges. Another possibility for achieving high spatial-resolved chemical information is the use of model-based reconstruction. The concept and first results will be presented.