  The electronic properties of thin films present quantum-size effects, which
are a consequence of the finite size of the system. Here we focus on the
investigation of these effects on the electronic energy loss of charged
particles moving parallel with thin metallic films. The energy loss is
calculated, within linear-response theory, from the knowledge of the
density-response function of the inhomogeneous electron system, which we
evaluate either in the random-phase approximation or with the use of an
adiabatic and local exchange-correlation kernel.
