CORE-HOLE DECAY MECHANISM IN RU STUDIED BY AUGER-PHOTOELECTRON COINCIDENCE SPECTROSCOPY

In order to explore the photoexcitation and decay mechanism of holes c reated 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 success fully modelled by atomic-like multiplets of the p(5)d(8) and d(6) conf igurations respectively, meaning that the core hole is suddenly screen ed. Furthermore, the photoemission spectrum cannot be simply described by a 4p(1/2),4P(3/2) spin-orbit doublet, but the angular momentum cou pling between the 4p core hole and the 4d open shell must be considere d, The Auger electrons emitted in coincidence with the satellite featu re, shifted 10 eV below the 4p core level, have a high energy threshol d that exceeds the threshold of conventional Auger measurements by an amount corresponding to the downward energy shift of the satellite fea ture. 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,Aug er emission could be explained by correlation effects. (C) 1998 Elsevi er Science B.V. All rights reserved.