Inelastic neutron scattering

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In condensed matter research, inelastic neutron scattering is a experimental technique to study atomic and molecular motion as well as magnetic excitations. It distinguishes itself from other neutron scattering techniques by resolving the change in kinetic energy that occurs when the collision between neutrons and sample atoms is an inelastic one. Results are generally communicated as inelastic scattering law S(q,ω), sometimes also as dynamic susceptibility χ(q,ω) where the scattering vector q is the difference between incoming and outgoing wave vector, and is the energy change experienced by the scattered neutron. When results are plotted as function of ω, they can often be interpreted in the same way as spectra obtained by conventional spectroscopic techniques; insofar inelastic neutron scattering can be seen as a special spectroscopy.

Inelastic scattering experiments normally require a monochromatization of the incident beam and an energy analysis of the scattered neutrons. This can be done either through time-of-flight techniques (neutron time-of-flight scattering ) or through Bragg reflection from single crystals (neutron triple-axis scattering , neutron backscattering). Monochromatization is not needed in echo techniques (neutron spin echo , neutron resonance spin echo ).