Study of the angular distribution asymmetry parameter in np photoionization of high-Z atoms: Impact of the relativistic and correlation effects on the Cooper minimum

Cooper minima (CM) in photoionization are effective tools to study the impact of relativistic and correlation effects as its location is dramatically dependent on these effects. For a particular subshell, the CM typically appears as a minimum in the cross-section (σ) and strongly affects the angular distribution asymmetry parameters (β). Owing to the correlation and relativistic effects, the location of CM shows a large sensitivity and, therefore, β also. In the present work, a theoretical study of the photoionization angular distribution parameter (β) of 6p, 5p and 4p photoionization is done using relativistic many-electron techniques. Earlier work investigated β in the 6p subshell photoionization up to Z=100 using the Dirac-Slater (DS) method [1]. The present work shows the behaviour of β up to Z=120 applying more precise methods; Dirac-Hartree-Fock (DHF) [2] which includes relativistic effects and exchange. and the relativistic random phase approximation (RRPA) [3,4] which includes both initial and final state correlation and relativistic effects. To spotlight the attributes of relativity and correlation effects, heavy and super heavy atoms, such as Rn (Z=86), Ra (Z=88), No (Z=102), Cn(Z=112), Og (Z=118), and Ubn (Z=120) are investigated.

*Work supported by the Office of Science, US Dept. of Energy (STM) and DST-SERB-CRG Project No CRG/2022/000191, India (JJ)

Reference

[1] S. T. Manson, C. J. Lee, R. H. Pratt, I. B. Goldberg, B. R. Tambe, and A. Ron, Phys. Rev. A, 28,2885 (1983).

[2] I. P. Grant, Relativistic Quantum Theory of Atoms and Molecules: Theory and Computation, Springer (2010).

[3] W. R. Johnson and C. D. Lin, Phys. Rev. A, 20, 964 (1979).

[4] W. R. Johnson, C. D. Lin, K. T. Cheng, and C. M. Lee, Phys. Scr., 21, 409 (1980).