Giant resonances in photon emission spectra of metal clusters

We consider radiative processes in collisions of electrons with metallic clusters and demonstrate that the cluster giant resonance structure manifests itself in the photon emission spectrum. This effect occurs because the cross section of the process is mainly determined by the dynamical polarizability of the cluster. We also demonstrate that the diffraction of electrons at the cluster edge adds some peculiar oscillatory structure to the cross section as a function of the photon frequency and as a function of the transferred momentum of the scattered electron. The results are generalized for ion-cluster and cluster-cluster collisions.