The Ionization of Inner Shells of Atoms Taking Account of Outer Shell Rearrangement

Abstract

The application of the general many-body theory and methods formulated with its help, in particular, the so-called random phase approximation with exchange (RPAE) /1–4/ and the many-body perturbation theory (MBPT) /5/, allows us to achieve a rather satisfactory description of ionization processes for many outer and intermediate shells in a number of atoms. It appears that the effect of interaction among all electrons of a given subshell is rather significant and ionization has to be considered as a many-electron process, because all electrons of a subshell take part in it. The study of the collective nature of the ionization process in the outer and intermediate shells is very important for the theory of many-electron atoms. A significant result obtained in the investigation of the influence of interelectron interaction on the ionization process is the observation of its important role /3,6,7/. Especially strong interelectron correlations manifest themselves in the action of a many-electron shell upon the few-electron shell. The study of photoionization of outer ns2 noble gas atom subshells demonstrates that the corresponding cross section is strongly affected by the outer np6 subshell, which acts as a powerful screen, completely modifying the form of the cross section curve /3/. For 5s2 subshells in Xe, Cs, and Ba it appears that not only the effect of the outer np6 but also the inner 4d10 subshell prominent.