Many-electron effects in 2p photoionization and Auger decay of atomic aluminium

High-resolution 2p photoionization and subsequent Auger decay of atomic Al have been investigated both experimentally and theoretically. Fine-structure-resolved experimental main and satellite photoelectron spectra were reproduced using extensive relativistic multiconfiguration Dirac–Fock calculations. Emphasis was placed on the electron correlations and how they affect the coupling of the valence and semi-valence electrons. The Auger electron spectrum was used to probe the electron correlation between the three electrons above the ionized 2p orbital and a breakdown of the two-electron picture describing the Auger emission was observed. Continuum wave selection was used to expound the intensity behaviour seen in the Auger electron spectra. Direct double photoionization thresholds and behaviour of the relative partial cross section as a function of photon energy during 2p ionization were experimentally obtained from the Auger spectra.