Eur. Phys. J. D 61, 267-283 (2011)
https://doi.org/10.1140/epjd/e2010-10294-8

Screening constant by unit nuclear charge calculations of ^1,3S^e, ^1,3P^o and ^1,3D^e intershell Rydberg states of the helium-like ions below the N = 2 hydrogenic thresholds

UFR Sciences and Technologies, Department of Physics, University of Ziguinchor, 523 Ziguinchor, Senegal

Corresponding author: ^a aminafatima_sakho@yahoo.fr

Received: 18 May 2010
Revised: 27 August 2010
Published online: 3 December 2010

Abstract

The ¹S^e, ³S^e, ¹P, ³P, ¹P, ³P, ¹D^e and ³D^e 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 2sns¹S^e, 2snp¹P and 2pnp¹D^e () autoionizing states with 11 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 S^e, P and D^e doubly excited states as well as in lower than in heavy-Z two-electron systems.