RIXS at the cerium L3-edge of Ce(III) and Ce(IV) systems: some observations

We report recent observations of resonant inelastic X-ray scattering (RIXS) at the cerium L-3-edge of CePO4, CeO2, and Ce3+ ion in aqueous solution. The intensity of the emission spectrum, including the dispersive Raman below the edge and the emerging nondispersive fluorescence above the edge, was recorded with a solid-state detector with low-energy resolution and a WDX detector with modestly high-energy resolution. The yield of the emission was used to monitor the cerium L-3-edge X-ray absorption near edge structures (XANES) in a constant initial state (CIS) mode as the photon energy sweeps across the cerium L-3-edge. The CIS XANES is compared with the XANES recorded using the nondispersive fluorescence yield, L-alpha, in a constant final state (CFI) mode. It is found that the Raman yield dominates the total emission in the pre-edge region and diminishes rapidly at threshold. The RIXS of Ce3+ (i)n aqueous solution exhibits similar behavior as CePO4. The post-whiteline RIXS intensity of CePO4 exhibits a correlation with excitation energy. CeO2 also exhibits a less intense whiteline in CIS XANES compared with the XANES detected with normal fluorescence. The implications of these observations with improved instrumental resolution are noted.