A study of transition metal K absorption pre-edges by resonant inelastic x-ray scattering (RIXS)

The K absorption pre-edge structure arises from excitations into the lowest unoccupied states that are partly formed by metal 3d orbitals. The pre-edge energy position, intensity and spectral shape can give valuable insight into the metal site symmetry and electronic configuration. The excited electronic states that form the absorption pre-edge subsequently decay radiatively. This fluorescence decay can be recorded using a crystal spectrometer that has a similar energy bandwidth as the incident beam. Plotting the fluorescence intensity versus incoming and outgoing energy yields three-dimensional plots that offer numerous possibilities for further analysis. In this paper we show that resonant inelastic X-ray scattering (RIXS) considerably facilitates separation of the K pre-edge structure from the strong dipole allowed transitions at higher incident energies. Previously unobserved spectral features could be revealed. The spectra along the energy transfer axis contain information on the electronic structure that is complementary to K-edge absorption spectroscopy.