Grazing-exit electron probe X-ray microanalysis (GE-EPMA): Fundamental and applications

Electron probe microanalysis (or Scanning electron microscope-energy dispersive X-ray spectrometry) has been studied under grazing-exit conditions. That is, characteristic X-rays are detected at a very small take-off (exit) angle; the technique is known as grazing-exit electron probe microanalysis (GE-EPMA). Fundamental aspects, instrumentation, and characteristics of grazing-exit electron probe X-ray microanalysis method are described here. Since the observation depth decreases as the exit angle decreases, theoretically to a few nanometers, surface analysis is possible in grazing-exit electron probe X-ray microanalysis. Of course, the size of the electron beam is also small-less than 1 μm, enabling localized surface analysis. In the case of total reflection X-ray spectrometry that allows surface analysis, the whole sample surface must be flat. However, the requirement for flatness is not as strict in grazing-exit electron probe X-ray microanalysis. Grazing-exit electron probe X-ray microanalysis measurements can easily be applied using a commercially available electron probe microanalysis (or Scanning electron microscope-energy dispersive X-ray spectrometry) instrument. To change and control the exit angle in grazing-exit electron probe X-ray microanalysis, the inclination of the sample stage or movement of the X-ray detector is all that is required. Theoretically, this study shows that grazing-exit electron probe X-ray microanalysis would be useful in improving the lateral resolution of the sample surface. In addition, the study demonstrates that grazing-exit electron probe X-ray microanalysis can be applied successfully for surface, thin-film, and particle analyses. As an optional method of electron probe microanalysis, grazing-exit electron probe X-ray microanalysis will be useful in expanding the research fields of normal electron probe microanalysis.