Fig. 2.

XAS fine structure and valence of UBi₂ and USb₂. a The x-ray absorption of UBi₂ and USb₂ on the O-edge of uranium is compared with (bottom) multiplets simulations for 5 f¹ (U⁵⁺), 5f² (U⁴⁺), and 5f³ (U³⁺). b A negative second derivative (SDI) of the XAS data and simulated curves, with drop-lines showing feature correspondence. Noise in the SDI has an amplitude comparable to the plotted line thickness, and all features identified with drop-lines were consistently reproducible when moving the beam spot. Prominent absorption features are labeled peak-A (UBi₂, hυ = 99.2 eV), peak-B (USb₂, hυ = 98.2 eV), and peak-C (USb₂, hυ = 100.8 eV). Source data are provided as a Source Data file