X-ray excited Pu core–valence–valence and core–core–valence Auger line-shapes were used in combination with the Pu 4f photoelectron peaks to characterize differences in the oxidation state and local electronic structure for Pu compounds. The evolution of the Pu 4f core-level chemical shift as a function of sputtering depth profiling and hydrogen exposure at ambient temperature was quantified. The combination of the core–valence–valence Auger peak energies with the associated chemical shift of the Pu 4f photoelectron line defines the Auger parameter and results in a reliable method for definitively determining oxidation states independent of binding energy calibration. Results show that PuO2, Pu2O3, PuH2.7, and Pu have definitive Auger line-shapes. These data were used to produce a chemical state (Wagner) plot for select plutonium oxides. This Wagner plot allowed us to distinguish between the trivalent hydride and the trivalent oxide, which cannot be differentiated by the Pu 4f binding energy alone.
The compound (I) crystallises in a form that is convenient for structure analysis by X-ray difiraction. The crystals belong to the monoclinic system, with a = 6-98, b = 10.55, c = 5.46 A, and p = 944O, and there are two molecules in the unit cell, with the space group P2Jm. The molecule is bisected by a crystallographic plane of symmetry. The benzenoid ring, which lies perpendicular to this plane, is itself coplanar; but the quasiquinonoid residue is non-coplanar, and the two carbonyl bonds are not collinear. Bond lengths and bond angles have been determined with moderate accuracy, including those in the three-membered ring; and the stereochemistry has been studied in some detail at the heavily strained carbon atoms by which this ring is fused to the naphthaquinone system.
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