Neutron spectroscopy
is a spectroscopic method of measuring the atomic and magnetic motions of atoms. Inelastic neutron scattering observes the change in the energy of the neutron as it scatters from a sample and can be used to probe a wide variety of different physical phenomena such as the motions of atoms, the rotational modes of molecules, sound modes and molecular vibrations, recoil in quantum fluids, magnetic and quantum excitations or even electronic transitions.