Inaccuracies with the Hall technique due to continuum variation in the analytical microscope

SUMMARY We have identified a source of extraneous (non‐sample) continuum in analytical microscopes with high‐angle EDS detectors. The extraneous continuum is generated by specimen‐scattered electrons but is not associated with a characteristic peak. This peakless continuum varies in magnitude with position across a grid and can cause large errors in quantitation with the Hall technique. The use of a modified specimen holder and an objective lens with a widened exit bore in the lower pole piece reduces the peakless continuum to acceptable levels in our instrument. Peripheral standards attached to the specimen can further reduce the impact of this extraneous continuum. Analytical microscopes with horizontal EDS detectors can also have serious problems with continuum variation across a grid, although the effect is likely due to X‐ray absorption by the specimen holder rather than extraneous continuum.