The main inelastic scattering mechanisms are:
i) Phonon excitation (heat).
ii) Plasmon excitation (valence electrons).
iii) Single electron excitation (inner and outer shell scattering).
iv) Direct radiation losses (Bremsstrahlung radiation due to deceleration of the electron beam in the Coulomb field of an atom).
v) Excitation of conducting electrons leading to secondary electron emissions.
The incident electron energy loss induced by phonon excitation in EMs is very small and is not detectable with current instruments, including high energy resolution EELS. Therefore, those electrons are still considered as zero-loss electrons in EELS profiles. The energy loss of electrons due to phonon excitations is a few 10 meV.
Table 3999 shows that electrons interact with 1 electron, many electrons, 1 nucleus, and many nuclei in solids.
Table 3999. Effects of interactions of electrons in solids.
||Interaction with electron(s)
||Interaction with nucleus/nuclei
||Electron Compton effect; electron excitation (from 50 eV to a few keV: EDS and EELS)
||Plasmon excitation (< 50 eV, ~100 nm TEM specimen); Cerenkov effect
||Rutherford scattering; phonon scattering (< 1 eV, heat)
Figure 3999 shows the angular distribution of phonon-scattered electrons as a function of scattering angle in EMs.
Figure 3999. Phonon scattering.