Nonrelativistic double photoeffect on lithium-like ions at high energies

Abstract

The total cross section for double ionization of lithiumlike ions by a high-energy photon is calculated in leading order of the nonrelativistic perturbation theory. The partial contributions due to simultaneous and sequential emissions of two electrons are taken into account. The cross section under consideration is shown to be related to those for double photoeffect on the ground and excited 2 1,3 S states of heliumlike ions. The double-to-single ionization ratio is equal to R = 0.288/Z 2 for lithiumlike ions with moderate nuclear charge numbers Z. However, even for the lightest three-electron targets such as Li and Be + , analytical predictions are found to be in good agreement with the numerical calculations performed within the framework of different rather involved approaches.

Triple ionization of lithium-like ions by photon impact

“…Note that the probability W 2s has rather complicated dependence on the nuclear charge Z (see Table 1). For photon energies higher than the double K-shell ionization threshold, the single photoionization cross sections for Li-and Helike ions are related to each other as follows [18] σ + (Li) 17 16 σ + (He). (8) It yields (9) In the high-energy non-relativistic limit, the double-to-single photoionization ratio is given by the scaling [5,19,20] R 2+ (He) = 0.090Z −2 .…”

“…In the asymptotic high-energy region, the photoionization ratio R 2+ (Li) obtained within the framework of the non-relativistic perturbation theory is given by [18] R 2+ (Li) = 0.288 Z −2 .…”

Double Ionization of Lithiumlike Ions by Compton Scattering of High-Energy Photons

“…For the Li atom, numerical calculations are performed within the framework of different sophisticated approaches [22 -25]. In the case of the Li isoelectronic sequence, a single analytical result has been obtained using perturbation theory [17].…”

“…As in photoabsorption [17], in Compton scattering on Li-and He-like ions the cross sections for ionization of KL-electron pairs are related with each other as follows:…”

“…Now we shall consider the indirect ionization of lithiumlike ions in the ground state, namely, the channel of single ionization with excitation of different autoionizing states. As in the case of photoabsorption, the cross section (3) is related to the corresponding cross sections for heliumlike ions [17]. However, unlike as for the photoeffect, in Compton scattering the target can be populated into the ns and np electron states with the principal quantum numbers n 2 [4,13].…”