Inelastic neutron scattering is an experimental technique for studying various properties of materials. A beam of neutrons of a particular energy is shot at a sample at a particular angle with respect to the crystal lattice. The energy of neutrons scattered by the sample is recorded, and the experiment is repeated at different angles and beam energies. The scattered neutrons lose some of their energy to the sample, so the scattering is inelastic. The results of inelastic neutron scattering are readily interpreted in terms of the wave nature of particles. The incident neutron beam is a wave with a frequency proportional to the neutron energy. The crystal preferentially absorbs waves with frequencies that correspond to its natural modes of vibration. Note that the vibrations can be magnetic or acoustic. Thus, the modes of the sample can be inferred by mapping out how much energy is absorbed from the incident beam as a function of the incident beam energy. Inelastic neutron scattering has also been used to study acoustic oscillations and their corresponding quasiparticles in liquids.