Inelastic X-ray scattering study of Cr(110): from low momentum transfer to the Compton scattering limit Original Research Article

Inelastic X-ray scattering (IXS) is an important tool to study a large number of physical properties in condensed matter systems. We use this technique to study electronic excitations in Cr(110). The IXS spectra were measured at sector 12-ID-B (BESSRC) at the APS. We used a backscattering geometry for the analyzer crystal, Ge (444) at 7.6 keV and Ge (555) at 9.5 keV. We used the BESSRC cryogenically cooled monochromator to select the desired energy, 180 meV resolution was obtained when using the Si (333) reflection. The spectra were obtained by scanning the incident energy with a fixed analyzer setting. Inelastic X-ray scattering spectra were measured for a range of momentum transfers extending from 0.80 to 5.0 Å−1. We find spectral features corresponding to plasmons excitations, as well as a second peak corresponding to excitation from the 3p core states to the 3d valence states of Cr. This peak shows strong momentum dependence with no detectable intensity at low momentum transfer. We observed at high momentum transfer the appearance of a Compton scattering peak.