Effect of additional monopole electron ejections on the final ion charge spectra following the cascade decay of electron vacancies in the gold atom

Abstract

The probabilities of the formation of final ions produced by the cascade decays of vacancies in the K, L, M, N, and O shells of the gold atom are calculated. Simulation of the cascade decays of vacancies is performed by direct construction and analysis of decay trees using branching ratios and transition energies calculated in the Pauli–Fock approximation for multivacancy electron configurations arising in the course of the cascade decay. Accounting for additional monopole ejections of electrons (shake-off) accompanying the cascade transitions leads to a slight increase in the average charges of the final ions, by 0.15–0.23e. The largest relative increase in the calculated average charges of the final ions (by 3.6–3.9%) is observed upon the cascade decay of vacancies in 4p_3/2, 4d_3/2, and 4d_5/2 subshells, and the smallest (by 0.8%) occurs in the decay of 4f-vacancy. Despite insignificant changes in the average ion charges, the structure of the charge spectra in some cases changes noticeably enough when additional electron ejections are taken into account. It is expected that in simulation of the cascade energy reemission processes when heavy atoms are used as radiosensitizers, the effect of accounting for shake-off processes will be insignificant.