High-resolution study of the x-ray resonant Raman scattering process around the 1s absorption edge for aluminium, silicon, and their oxides

X-ray resonant Raman scattering (RRS) spectra of Al, Al₂O₃, Si, and SiO₂ were measured at the European Synchrotron Radiation Facility, using a high-resolution Bragg-type curved crystal spectrometer. The x-ray RRS spectra were collected at several beam energies tuned below the 1s absorption thresholds of Al and Si. Differences in the spectral features between the elemental samples and the oxide ones were clearly observed. The data were interpreted using the second-order perturbation theory within the Kramers-Heisenberg (KH) approach. It is shown that, using the KH formalism, oscillator strengths that are similar to the ones deduced from x-ray absorption measurements can be extracted from emission x-ray RRS spectra. The total cross sections for the x-ray RRS process were derived for the different photon beam energies and compared with theoretical predictions. For elemental silicon, the weak 1s-3p excitation was observed and found to be consistent with results of density of states calculations.