Inter-shell correlations in the inelastic scattering of fast electrons of the outer subshells in Ar and Xe

Abstract
The influence of neighbouring subshells on the density of the generalized oscillator strength (GOS) of the outer ns2 subshells has been studied for argon and xenon. Many-electron correlations within a single subshell and inclusion of inter-shell interactions have been considered in the random-phase approximation with exchange. The calculations were performed with energies omega transferred to the atom in the range from the ionization threshold up to 14 Ryd and transferred momenta q from 0 up to 2.5 au. The monopole, dipole and quadrupole components of the GOS densities have been taken into account. It was demonstrated that ns2 subshell ionization by fast electrons is, for small transferred momenta, entirely collective, and is totally determined by the influence of the neighbouring-shell electrons. With an increase in the transferred momentum, the main contribution to the total GOS density comes from the monopole and quadrupole components which are much less affected by many-electron correlations than the dipole component.