Relativistic and correlation effects in the photoionization dynamics of oganesson $(Z=118)$: Spin-orbit-interaction-activated interchannel coupling effects

High-$Z$ atoms are excellent laboratories to study the combination of relativistic and many-electron correlation effects in electronic structure and dynamics. In the present work, the relativistic-random-phase approximation at different levels of truncation is employed to explore the final-state correlation effects in the photoelectron dynamics of the heaviest known element in the Periodic Table: oganesson (Og) with $Z=118$. The focus of this work is to illustrate the relativistic effects resulting from coupling different photoionization channels arising from spin-orbit split subshells, termed the spin-orbit-interaction-activated interchannel coupling effect. Comparison with the photoelectron dynamics of Rn on a qualitative level is also carried out, since Og is a homologue of Rn. The photoelectron dynamics of $7p,7s$, and $6d$ subshells are investigated and differences between Og and Rn, due to enhanced relativistic effects, are investigated.

Figure 1

Photoionization cross section for $7p$ subshells of Og calculated in the RRPA. A magnified view in the region of the Cooper minimum is shown in the inset.

Figure 2

Photoionization cross section for $6p$ subshells of Rn [33]. A magnified view in the region of the Cooper minimum is shown in the inset.

Figure 3

Angular distribution asymmetry parameter for Og $7p$. The inset shows the Rn $6p\beta$ [33].

Figure 4

Photoionization cross section of the Og $6d$ calculated in RRPA. The inset shows the Rn $5d$ cross section [32].

Figure 5

Absolute value of the dipole matrix element for Og $6d\to \varepsilon f$ transitions calculated with a 20-channel RRPA.

Figure 6

Angular distribution asymmetry parameter for Og $6d$. The inset shows the Rn $5d\beta$ [32].

Figure 7

Photoionization cross section for Og $7s$ calculated in the RRPA. The inset displays the Rn $6s$ cross section [33].

Figure 8

Dipole matrix element of Og for the transition $7s\to \varepsilon p_{3/2}$.

Figure 9

Dipole matrix element of Og for the transition $7s\to \varepsilon p_{1/2}$.

Figure 10

Photoelectron angular distribution asymmetry parameter for the Og $7s$ subshell. The inset shows the Rn $6s\beta$ [33].