2. Oxidation state and geometric structure analysis

Systematic studies of actinides at all oxidation states have been carried out to determine precise absorption thresholds and thus obtain useful references for the speciation of these elements. Figure 3 shows an example of the variation in energy of neptunium's L _III threshold as a function of its oxidation state. Degrees III and IV are quite distinct, allowing them to be unambiguously identified. On the other hand, Np(V) and Np(IV) are located in approximately the same position. However, they can be distinguished by the shape of the absorption jump. Pentavalent...