We report measurements of the Na 1s contribution to the nonresonant inelastic x-ray scattering (NRIXS) from NaCl and NaF. Prior x-ray absorption studies have observed two pre-edge excitons in both materials. The momentum transfer-dependence (q-dependence) of the measured cross-section and real-space full multiple-scattering and Bethe-Salpeter calculations determine that the higher-energy core excitons are s-type for each material. The lower-energy core excitons contribute at most weakly to the NRIXS signal, and we propose that these may be surface core excitons, as have been observed in several other alkali halides. We discuss the limited sensitivity of NRIXS measurements to d-type final states when investigating 1s initial states.
Citation: Physical Review B (Condensed Matter and Materials Physics)
Issue: No. 4
Pub Type: Journals
core-hole exciton, non-resonant x-ray Raman scattering, x-ray absorption spectroscopy