Many-electron effects in the Ar 2p(-1)4s -> 3s(1)3p(5)(P-3)4s resonant Auger transitions

Many-electron effects associated with high-lying Rydberg states in the fina l state of the Ar 2p(-1)4s --> 3s(1)3p(5)(P-3)4s resonant Auger transitions result in numerous line components in the experimental spectrum. Taking ad vantage of the cascade process we study the quasi-continuum features of the 3s(1)3p(5)(P-3)4s Auger peaks with the aid of second-step Auger spectra. W e discuss the lineshape of the second-step spectra which characteristically consist of very narrow peaks. We also describe model calculations which ha ve been carried out by including the mixing of the configurations using the multiconfiguration Dirac-Fock method. They are found to reproduce the main features of the 3s(1)3p(5)(P-3)4s peaks reasonably well.