1. Measurement principle and characteristics

Energy loss spectra of electrons backscattered (or possibly transmitted) by a solid target reveal characteristic structures observed at E ₀ – E _c where E ₀ is the initial electron energy and E _c is a characteristic energy associated with the excitation of collective or individual phenomena.

• Collective excitations are essentially vibrations of the ion lattice (phonons) or oscillations of valence electrons (plasmons).

• Individual excitations cover two kinds of phenomena: vibrations of molecules, generally adsorbed on the surface, or of molecular groups, and excitations of electrons in the solid. The latter...