Lg. Gerchikov et al., MANY-BODY TREATMENT OF THE PHOTON-EMISSION PROCESS IN ELECTRON-CLUSTER COLLISIONS, Journal of physics. B, Atomic molecular and optical physics, 31(10), 1998, pp. 2331-2341
We present the results of the many-body treatment of the bremsstrahlun
g (BrS) process in collisions of fast electrons with metal clusters. W
e concentrate our attention on the range of photon frequencies charact
eristic for plasmon excitations in clusters. The dynamic polarizabilit
y of a cluster in this frequency range is very large and it determines
the value and behaviour of the cross section of the process as a func
tion of various parameters. When calculating the cross section of the
process, we treat the dynamic,response of the cluster in the random-ph
ase approximation with exchange, using wavefunctions of the Hartree-Fo
ck jellium model and also in the resonance plasmon approximation. The
latter approach is well applicable for the treatment of collective exc
itations of electrons in clusters. We analyse the spectral and angular
distributions of the emitted photons, as well as the collision veloci
ty dependence of the cross section for small sodium clusters and demon
strate that collective electron excitations determine the main feature
s of the BrS cross section.