Interference effects in L-shell atomic double photoionization

Abstract

Angular correlation pattern in two-electron continuum is very similar in double photoionization (DPI) of a neutral atom γ + A → A 2+ + 2e − and electronimpact ionization of the corresponding singly charged ion e − + A + → A 2+ + 2e −. This allows us to identify and to interpret interference effects in DPI of various L-shell atomic targets such as the metastable He* 1s2s 1 S and the ground state Li 1s 2 2s and Be 1s 2 2s 2 .

Signature of Two-Electron Interference in Angular Resolved Double Photoionization of Mg

“…As was argued in Ref. [5], the Gaussian width may be linked to the radial extent of the target orbital bound to the singly charged ion. A more sparse target orbital can be reached by a larger number of partial waves of the electron in the continuum, which leads to a narrower Gaussian.…”

“…At the same time, the radial orbital bound to the He þ ion has only one area of charge localization and thus, according to the arguments of Ref. [5], the corresponding DPI amplitude can be represented by just a single Gaussian.…”

“…The situation is much more complicated in double photoionization (DPI) where there are no simple bounds on the individual photoelectron angular momenta ' 1 and ' 2 other than coupling to the total angular momentum of the pair, and a large number of radial integrals contribute to the total integrated photoionization cross section. Hence, there is no simple analogue of the Cooper minimum in DPI.Nevertheless, a strong effect of the target electronic structure was observed in calculations of the angular correlation pattern in the two-electron continuum [5]. It has been shown that (i) for a given symmetry of the electron pair the angular correlation of DPI mimics the angular distribution of an e-impact ionization of the corresponding ion and (ii) the amplitudes of these processes are strongly determined by the radial extent and oscillations of the target orbital of the singly charged ion.…”

“…Nevertheless, a strong effect of the target electronic structure was observed in calculations of the angular correlation pattern in the two-electron continuum [5]. It has been shown that (i) for a given symmetry of the electron pair the angular correlation of DPI mimics the angular distribution of an e-impact ionization of the corresponding ion and (ii) the amplitudes of these processes are strongly determined by the radial extent and oscillations of the target orbital of the singly charged ion.…”

“…The whole of the Mg amplitude can be better described by the di-Gaussian parametrization proposed in Ref. [5] M g ð 12 Þ ¼ GðA 1 ; Á 1 ; 12 Þ þ e i GðA 2 ; Á 2 ; 12 Þ:…”