High resolution study of the inner-shell 3p–3d and 3p–5s resonance regions in calcium atoms.

Abstract: The 3p 54s 23d 1P1 and 3p 5(2P3/2)4s 25s 2[3/2]1 resonance regions of Ca atoms have been studied experimentally with the aid of synchrotron radiation excited electron spectroscopy. The strong configuration interaction of the 3p 54s 23d, 3p 54s 25s and several other nearly degenerate configurations leads to complex structures observed in the photoelectron yield spectrum. Multiconfiguration Dirac–Fock (MCDF) calculations have been performed for these 3p-excited resonances of neutral calcium and compared to experimental results. The excitation and subsequent autoionization of these resonances lead to the final ionic 3p 6 nl states from which new high-lying members of the Rydberg p-series have been resolved experimentally. These new levels agree reasonably well with calculations as well as with the extrapolation of the Rydberg formula. The post collision interaction (PCI) effect has been observed in the transition Ca+ 3p 53d4s 2P1/2,3/2→ Ca2+ 3p 6 and explained by means of the rather long core-hole lifetime, while the decay of Ca+ 3p 53d4s 4P1/2,3/2,5/2 states is not affected by PCI. [Copyright &y& Elsevier]