EPMA... .it all starts with Bragg’s Law. It’s all about crystals. WDS crystals are really the rate-limiting step to the usefulness of the EPMA technique. As such they represent the focal point of as much research as any other component of the instrument. There is an inherent need to improve the performance of crystals to assure the survival of the technique. As electron columns permit smaller and smaller spot sizes and as the need to analyze smaller and smaller things increases the search for improved crystals intensifies.

There are generally two crystal parameters that beg for improvement: 1) Energy Resolution and 2) Intensity (especially for light elements). The resolution of crystals is considered adequate for most applications but it’s always useful to have more resolution to better deal with overlapping lines. It’s also becoming useful to measure valence states by observing relative shifts in peak positions. Intensity is the thing that one never gets enough of. It seems that more and more applications demand more intensity. Trace element analysis, particle analysis, heat sensitive sample analysis, light element analysis all scream for more intensity.