Core-hole decay mechanism in Ru studied by Auger-photoelectron coincidence spectroscopy

In order to explore the photoexcitation and decay mechanism of holes created in the 4p core level in Ru, the N2,3VV Auger spectrum of the Ru(0001) surface has been measured in coincidence with several features of the photoemission spectra and vice versa. The main features of the core level photoemission spectrum and the Anger spectra can be successfully modelled by atomic-like multiplets of the p(5)d(8) and d(6) configurations respectively, meaning that the core hole is suddenly screened. Furthermore, the photoemission spectrum cannot be simply described by a 4p(1/2),4P(3/2) spin-orbit doublet, but the angular momentum coupling between the 4p core hole and the 4d open shell must be considered, The Auger electrons emitted in coincidence with the satellite feature, shifted 10 eV below the 4p core level, have a high energy threshold that exceeds the threshold of conventional Auger measurements by an amount corresponding to the downward energy shift of the satellite feature. This indicates that the excitation associated with the satellite feature is long-lived and participates in the Auger decay, Remaining differences between the experimental and the model spectra for the,Auger emission could be explained by correlation effects. (C) 1998 Elsevier Science B.V. All rights reserved.