Inelastic effects and energy filtering
Diffraction in metals and alloys: diffraction conditions

When a fast-moving electron penetrates a sample, several things can happen. It can pass through the sample:

• without interaction ;

• with one or more elastic interactions ;

• with one or more inelastic interactions ;

• with one elastic interaction, one inelastic interaction or a combination of several elastic and inelastic interactions.

Inelastic interactions are those that lead to one or more excitations of the electrons in the sample. Each interaction corresponds to a loss of energy in the incident electron.

The most likely is the collective excitation of free electrons (plasmons), but others are possible and can be used to obtain information about the elements present...