First measurement of a phonon dispersion curve by inelastic X-ray scattering

Inelastic scattering of 13.8 keV X-rays with very high energy resolution of E=55 meV was used to measure the phonon dispersion curves for theLA andLO modes in the [00] direction in Be. The results agree with inelastic neutron scattering data known from the literature. The X-ray scattering intensities of the phonon excitations for different momentum transfers are in very good agreement with the prediction from the scattering law.