secondary electrons (se) in in situ microanalysis

All electrons emitted from the surface of a solid except back scattered primary electrons. In practice, electrons emitted from the surface of a solid under particle bombardment which have a kinetic energy of less than $50 eV$ .

Source:

PAC, 1983, 55, 2023 (Nomenclature, symbols and units recommended for in situ microanalysis (Provisional)) on page 2026