Dynamics

In this chapter, we review the wavenumber and energy ranges covered by various dynamics measurement methods and then outline inelastic neutron scattering (INS) and inelastic X-ray scattering (IXS) in particular. We explain their principles and methods and pick up recent applications and developments. As an example of recent INS research, a study of a solid refrigerant is first introduced, since Å-level dynamics contributes to thermal properties. For another example, we look at recent advances on the boson peak, which is an excitation that is universally seen in structurally disordered systems. As an example of recent IXS studies, we pick up the measurement of phonon dispersion relations of Mg alloys, which are expected to be the next-generation structural material. In the last part of this chapter, we introduce recently developed measurement techniques of IXS in which Mössbauer nuclei are excited by synchrotron radiation and used for dynamic measurements.