Theoretical and experimental study of inner-valence-shell satellites above the double-photoionization threshold of argon

The Ar photoelectron lines located above the double-ionization threshold have been investigated both theoretically and experimentally. Their Anger decay, sorted in a coincidence experiment, is found to occur predominantly to the Ar2+(ID) final state. Calculations demonstrate that while some photolines can be labelled as 3s3p(5)(P-3)nl, none of them can be described as 3s3p(5)(P-1)nl because such a configuration is always weaker than doubly excited ones in the configuration-interaction (CI) description of the state. This is evidence of 'second-order satellites', which eve define as satellites dominated by a doubly excited configuration. The intensity of the photolines in the 45-58 eV binding energy region is qualitatively demonstrated to reflect correlation in the Ar(S-1) ground state, and is related to the singly and doubly excited configurations in the CI development of the latter.