2. A reminder of electron-matter interactions

When an electron beam of energy E ₀ penetrates a solid sample, it undergoes a number of interactions, both elastic and inelastic. Inelastic interactions cause a progressive loss of its energy, largely through transfer to electrons in atomic orbitals and to a lesser extent through radiative loss during interaction with the nucleus (braking radiation still often called Bremsstrahlung following the historical German term). Elastic interactions, mainly with the nucleus, also induce more or less abrupt variations in the direction of incident electrons ("scattering"). The result of these interactions is an "electron trajectory" for each electron, of finite length and random shape.

Numerical simulation, using a Monte Carlo method which models the random collisions of the incident electron with the target atoms, allows us to...