Electron probe microanalysis

Electron probe microanalysis (EPMA), also known as electron probe X-ray microanalysis, electron microprobe analysis (EMPA) or electron probe analysis (EPA) is a microanalytical and imaging technique used to non-destructively determine the chemical element composition of small volumes of solid materials. The device used for this technique is known as an electron probe microanalyzer (also abbreviated EPMA), often shortened to electron microprobe (EMP) or electron probe (EP).

Source: Wikipedia — Electron probe microanalysis (CC BY-SA 4.0)