Electronic structure of some binary uranium and thorium oxides and halides

X-ray photoelectron spectra of U and Th 4f core levels and valence bands have been recorded from UF4, UCl4, ThF4 and ThCl4 using a Kratos ES300 X-ray photo-electron spectrometer. The spectra are compared with their counterparts recorded from uranium and thorium dioxide surfaces. The results obtained are discussed as a function of metal ionicity, the covalency of the metal—ligand bond and the participation of 5f electrons in bonding.