L 2,3 -MM Auger spectra of argon have been measured with very high resolution using excitation by monochromatic synchrotron radiation. The photon energy was selected slightly above the 2p ionization threshold for creation of the single 2p core hole state only. The Auger spectra are thus free from any satellite lines originating from two-hole initial states and therefore well suited to study the configuration interaction in the final ionic state of the decay. Electron correlation is investigated by calculating the energies and intensities of the transitions using the multiconfiguration Dirac-Fock method and by comparing them with the experimental results.

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Angular distribution of the Xe M4–N4,5N4,5 Auger transitions has been determined from an experiment which was carried out by 3.6 MeV proton impact. In a comparison with existing relativistic calculations for the α 2 parameters a good agreement was found which confirms the validity of relativistic theory in describing the core–core Auger transitions.

The L 2,3 -MM Auger spectra of argon have been created bombarding the sample gas by either 2 keV electrons or 398 eV and 315 eV photons. The 2p photoionization created by 315 eV photons may be accompanied by a simultaneous excitation of another electron to an unoccupied orbital or to the continuum. High-energy electrons and 398 eV photons can ionize the 2s subshell which may lead to the L 1 -L 2,3 [M]-MM[M] satellite Auger transitions. Semiempirical kinetic energies of the L 2,3 [M]-MM[M] satellite Auger transitions have been estimated with the aid of MCDF calculations, the 2p shake-up spectrum, the L 1 -L 2,3 M Coster-Kronig spectrum and the final-state binding energies from optical data. Intensities of the transitions have also been calculated by using a MCDF code. A comparison of the semi-empirical and observed energies with the calculated and observed intensities has allowed us to assign a manifold of the satellite peaks in the measured spectrum. We have also investigated the changes in intensity distribution of satellites in passing from cascade satellites to those created via shake-off processes accompanying photoionization.