Beamline ID28 is dedicated to the study of phonon dispersion in condensed matter at momentum transfers, Q, and energy transfers, E, characteristic of collective atom motions. Inelastic X-ray scattering (IXS) is therefore closely related to inelastic neutron scattering (INS) techniques, and consequently largely shares the scientific questions addressed in fields ranging from life science to materials research. IXS is particularly suited for the study of disordered systems such as liquids and glasses in a Q,E-range inaccessible to INS and of samples only available in very small quantities (<< 1 mm3) and/or submitted to very high pressures (up to 100 GPa). The beamline characteristics are as follows:
Determination of the phonon dispersion, or more generally, of the high-frequency (THz) collective dynamics, allows to access various material properties such as sound velocities, elastic constants, interatomic force constants, phonon-phonon interactions, phonon-electron coupling, dynamical instabilities, relaxation phenomena etc. Applications of inelastic X-ray scattering from phonons on ID28 can be roughly divided into three categories: