Resonant magnetic x-ray scattering in a series of uranium compounds

We report results of x-ray scattering experiments on the antiferromagnetic uranium compounds UO2, USb, and (U0.85Th0.15)Sb. The energy dependence of the x-ray scattering cross section is reported in the range 3.5--3.9 keV, which includes the MIV and MV absorption edges. The energy dependencies are very similar and well represented by atomic-resonance methodology. Differences occur in the ratio of intensities (branching ratio) of the two absorption edges, which are larger in UO2 than in the other materials. Ab initio calculations based on atomic physics suggest that such differences may arise from differing 5f-electron configurations. Unfortunately, we have not measured accurately the absorption coefficient over the two edges, so that our corrections to the intensities must be regarded as qualitative. This prevents a quantitative comparison between the observed and calculated branching ratios. Consistent with the calculated cross section, the magnetic scattering of the σ-polarized incident beam is rotated to π polarization. No unusual effects were found at the MIV edge of Th in the pseudobinary compound