Low-energy electron bremsstrahlung from metal clusters

Expressions are derived allowing numerical calculation of the matrix element of the dipole moment between states that belong to a continuous spectrum for the case where a charged particle in an arbitrary orbital state is scattered by a spherically symmetric short-range potential. The calculation scheme is based on expanding a diverging matrix element into a sum of converging integrals. The method is used to study static bremsstrahlung of a slow electron scattered by sodium clusters. The bremsstrahlung cross section is shown to be resonant. The resonances arise at certain energies (depending on a cluster) of an electron having emitted a photon and are due to electron capture on quasi-steady-state levels.