Dynamic coherence effects in deep inelastic neutron scattering: Many-body treatment and intra-molecular terms

We investigate the presence and the extent of dynamic coherence effects in deep inelastic neutron scattering, as well as the possibility to apply simple corrections to take them into account. After starting with a general formalism, we focus on disordered systems with a particular reference to liquid neon, explicitly chosen as an example. Moving to a different scattering regime, we tackle dynamic coherence effects in deep inelastic neutron scattering from molecules, where energy transfers exceed their largest vibrational frequencies. Two species of dynamic coherence effects are identified: intermolecular and intra-molecular. As the former are qualitatively similar to the many-body coherence effects already dealt with, we focus on the latter, treating them with a standard vibrational spectroscopy approach. Supercritical heavy water and nanoconfined deuterium are analyzed as particularly suitable examples. Finally, we conclude that intra-molecular dynamic coherence effects are practically negligible in deep inelastic neutron scattering operated in the standard kinematic regime.