Secondary Electrons (SEs) Produced by inelastic interactions of high energy electrons with valence electrons of atoms in the specimen,causing the ejection of the electrons from the atoms. Pole piece Beam ⊙ SE III L23 L SE escape depth 10Secondary Electrons (SEs) • Produced by inelastic interactions of high energy electrons with valence electrons of atoms in the specimen, causing the ejection of the electrons from the atoms. 10