Electron capture into few-electron heavy ions: Independent particle model

Abstract

Abstract. We apply the density matrix theory to re-investigate the radiative electron capture into heavy ions with one valence electron. Attention has been paid particularly to the magnetic sublevel population of the residual ions, as described in terms of alignment parameters. Simple method, based on an independent particle model, which takes into account the Pauli principle, is proposed for evaluating the alignment of the excited ionic states. By making use of this method, detailed calculations are performed for electron capture into (initially) hydrogen-like and lithium-like europium, gold and uranium ions, and are compared with the results of the multiconfiguration Dirac-Fock approach.As seen from the calculations and from the comparison with available experimental results, the independent particle model provides a good estimate for the alignment parameters of few-electron heavy ions. Therefore, our simple model may help to understand the basic properties of the X-ray emission from heavy, few-electron ions without the need for invoking sophisticated MCDF calculations. PACS

Angular correlations in radiative cascades following resonant electron capture by highly charged ions

“…For highly charged ions, both the bound-bound and boundfree radiative electron transitions are usually well described by the IPM [40]. In this model the many-electron wave functions are simply approximated by single Slater determinants as obtained from the hydrogenic orbitals in order to take the Pauli principle into account.…”

Angular correlations in the two-photon decay of heliumlike heavy ions

“…In the high-Z domain, however, the structure of few-electron ions can already be reasonably well understood within the independent particle model (IPM). This model is well justified for heavy species especially, since the interelectronic effects scale with 1/Z and, hence, are much weaker than the electron-nucleus interaction [25,26,37]. Within the IPM, which takes the Pauli principle into account, the many-electron wave functions are approximated by means of Slater determinants, built from one-particle orbitals.…”

Fine-structure effects on the polarization of Kα1 radiation from heavy, highly-charged ions

“…1s 21 S 0 photons can be traced back to the effective parameter b eff 2 . Since the same parameter defines also the anisotropy of the Ka 1 line, its evaluation has been discussed in detail before [10,12]. In particular, it was shown that for high-Z ions the alignment parameters A 2 ðJ b ¼ 1; 2Þ and the weights N 1,2 in Eq.…”

“…1 S 0 electric dipole (E1) and 3 P 2 ? 1 S 0 magnetic quadrupole (M2) transitions, both of which contribute to the Ka 1 radiation [10][11][12].…”