Experimental and theoretical study of core-excited states of Mg II

The 2p(5)3s3p, 3p2, 3s4s, 3s3d, and 3s4f core-excited configurations of Mg II have been studied experimentally by beam-foil spectroscopy and theoretically by multiconfiguration Hartree-Fock calculations with Breit-Pauli relativistic corrections. The previously established energy levels belonging to the former four configurations have been reexamined leading to significant corrections of the 3p2 4D and 3s4s 4P levels. Many previously unidentified spectral lines have now been assigned allowing a confident set of energy levels of the nearly degenerate 3p2, 3s4s, and 3s3d configurations to be established. in addition, the higher lying 3s4f states have been studied allowing the assignment of the prominent, but unidentified line at 3480 angstrom to the 3s4f 4G11/2 --> 3s3d 4F9/2 transition, and the establishment of some 3s3d states which primarily decay by autoionization