A beam-foil study of Ni XIX and Cu XX and a theoretical survey of 2p⁵3l configurations from Ar IX to Cu XX

Abstract

The spectra of the neon-like ions Ni XIX and Cu XX have been studied by beam-foil techniques. About 30 lines have been used in each spectrum to derive the energy levels of the 2p53l configurations. The identifications are supported by systematic theoretical studies using the Slater-Condon parametric method with isoelectronic constraints in the fitting process, and the ab initio relativistic parametric potential method. Some earlier identifications have been revised in the sequence Ar IX-Cu XX.