Anomalous behaviour of X-ray absorption observed on the highly correlated cerium nitride (CeN) compound

In this study, we present recent X-ray Absorption Spectroscopy (XAS) results obtained on highly pure cerium nitride (CeN) compounds. CeN is the “archetype” of the strongly mixed-valent (MV) cerium compounds, where the ground state properties are governed by strong hybridization effects between the 4f and the conduction electrons. We will show that, in clear contradistinction with earlier results, the L$_{\rm III,II}$ absorption edges of cerium in CEN do not exhibit the two contributions usually observed in strong MV systems. Indeed, in all cases only one single white line is observed. This anomalous behaviour is related with similar results obtained recently on in-situ prepared CeN studied by both L$_{\rm III}$ absorption and Ce 2p X-ray photoemission (XPS). The possible influence of the presence of p conduction states to explain this anomalous behaviour is addressed