Resonant photoemission from CeNix (x = 1, 2 and 5)

High resolution (Delta E approximate to 50 meV) resonant photoemission recorded at the Ce 4d --> 4f threshold from CeNi, CeNi2 and CeNi5 is reported. With increasing Ni content, the centre of the Ni 3d-band is seen to approach the Fermi level, providing an explanation for the enhanced hybridisation in this series. Observation of the Kondo peak with increasing Ni content becomes less clear, however. This is partly due to a swamping of the photoemission signal at E-F by the Ni d-electrons, but may also indicate that interpretation of the spectroscopy for CeNi5 within the Kondo picture is reaching a limit of validity.