Relation of Kinetic Energies of Secondary
Electrons in Vacuum and Specimen
- Practical Electron Microscopy and Database -
- An Online Book -


This book (Practical Electron Microscopy and Database) is a reference for TEM and SEM students, operators, engineers, technicians, managers, and researchers.



In the SEM specimen, SE (secondary electron) kinetic energy in the specimen (Es) is given with respect to the bottom of the conduction band and SE kinetic energy into the vacuum (Ek) [1],
             Es = Ek + EF + Φ (for metals) ------------------------------------[4831a]
where EF -- Fermi energy
          Φ -- work function
         or Es = Ek + χ (for semiconductors and insulators) ---------------- [4831b]
where χ is electron affinity.

For metals, EF + Φ ≈ 10 eV and Ek ≈ 2.5 eV
For a semiconductor, Ek ≈ 2 eV and χ ≈ 5 eV
for an insulator, Ek ≈ 1 eV and χ = 1eV.

The moving electrons in the specimen and vacuum obey the refraction relation between their kinetic energies at the interface. Normally, the secondary electrons (SEs) have energies of less than 50 eV. 90% of secondary electrons have energies less than 10 eV and most SEs are in the energy range from 2 to 5 eV.


[1] Henke, B.L., Liesegang, J. & Smith, S.D. (1979) Soft X-ray induced secondary electron emission from semiconductors and insulators. Phys. Rev. B, 19, 3004–3021.




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