EFFECTS OF COSTER-KRONIG DECAY ON CE 3D-4F RESONANT PHOTOEMISSION SPECTRA OF CEOS2

We have measured the photoemission, total yield and partial yield spec tra of CeOs2 in the energy region of the Ce 3d-4f excitation. In the C e 3d-4f resonant photoemission and yield spectra, we observe the follo wing features. (1) In the Ce 4f and 4d photoemission spectra, the reso nance effect due to the Ce 3d(3/2)-4f excitation is weaker than that d ue to the 3d(5/2)-4f excitation. (2) At the 3d(3/2)-4f threshold, thre e Auger structures appear at the higher binding energy side of the Ce 4d core level. (3) The intensity of the partial yield (photoemission i ntensity at 5 eV kinetic energy) is stronger at the 3d(3/2)-4f excitat ion threshold than at the 3d(5/2)-4f threshold. The origin of these fe atures is discussed in terms of a Coster-Kronig decay channel (3d(3/2) -3d(5/2)4f Auger transition) such as 3d(3/2)4f-->3d(5/2)epsilon f (3d and epsilon f denote a 3d core hole and a continuum f state, respectiv ely). The occupation number of 4f electrons in CeOs2 is estimated to b e similar to 0,75 from the analysis of the Ce 3d absorption spectrum. (C) 1998 Elsevier Science B.V.