Vibrational spectroscopy using inelastic neutron scattering: Overview and outlook

Inelastic neutron scattering (INS) spectroscopy is a technique for obtaining vibrational spectra from determination of the change in energy of a neutron when it passes through a material. These inelastic events are the fundamental process in neutron thermalization. As a spectroscopic technique, INS offers the unique capability of providing isotopic sensitivity with H being a very much stronger scattering center than all other atoms including deuterium. Neutron scattering has no selection rules other than those resulting from variation in nuclear scattering lengths. Neutron scattering in general depends on known interaction strengths with nuclei and on atomic dynamics. The theory of neutron scattering in general is extensively developed and permits direct comparison of theory with experiment without intervening approximations. This permits direct evaluation of the ability of computational methods in providing a valid description of nuclear dynamics in a material. The prospect for rapid advances in the application of INS vibrational spectroscopy in the near term due to new neutron facilities and on-going software development is reviewed and illustrated.