A study of the electronic structure of the actinide tetrahalides UF4, ThF4, UCl4 and ThCl4 using vacuum ultraviolet photoelectron spectroscopy and SCF-Xα scattered wave calculations

The gas phase helium (i) photoelectron spectra of the actinide tetrahalides UF4, ThF4, UCl4, and ThCl4 have been recorded. The spectra have been interpreted with the aid of nonrelativistic multiple-scattering SCF-Xα calculations and are consistent with an effective tetrahedral geometry for these molecules in the gas phase. Both the calculations and the spectra indicate that the 5f electrons in UF4 and UCl4 are essentially localized on the central metal.