Screening constant by unit nuclear charge calculations of $^{1,3}$ Se, $^{1,3}$ Po and $^{1,3}$ De intershell Rydberg states of the helium-like ions below the $\rm N$ = 2 hydrogenic thresholds

Abstract

The \(_{2}(1,0)_n^{+}\)1Se, \(_{2}(1,0)_{n}^{-}\)3Se, \(_{2}(1,0)_{n}^{-}\)1P\(^{\circ}\), \(_{2}(1,0)_{n}^{+}\)3P\(^{\circ}\), \(_{2}(0,1)_{n}^{+}\) 1P\(^{\circ}\), \(_{2}(0,1)_{n}^{-}\)3P\(^{\circ}\), \(_{2}(1,0)_{n}^{+}\) 1De and \(_{2}(1,0)_{n}^{-}\)3De intershell autoionizing states of the helium-like ions are studied using the screening constant by unit nuclear charge (SCUNC) method in the framework of a semi-empirical procedure. The results up to Z = 10 compared well to the available experimental and theoretical literature data. In addition, the possibility to apply the SCUNC method in the calculations of energy resonances of heavy-Z helium-like ions is demonstrated in the present work where energy positions for some low-lying 2sns1Se, 2snp1P\(^{\circ}\) and 2pnp1De (\(n \le 4\)) autoionizing states with 11 \(\le Z \le 28\) are tabulated and comparison with double sums over the complete hydrogen spectrum calculations [A.I. Ivanov, I.U. Safronova, Opt. Spectrosc. 75, 506 (1993)] is made. A host of results presented in this paper may be useful guideline for future experimental and theoretical investigations in high-lying \(^{1,3}\)Se, \(^{1,3}\)P\(^{\circ}\) and \(^{1,3}\)De doubly excited states as well as in lower than in heavy-Z two-electron systems.