Neutrons for a dynamical access to mutual arrangement and interactions in molecular liquids

In-depth knowledge of the interactions ruling the dynamics of molecular liquids is crucial to understand their nano-scale properties, also relevant to active fields as biology and alternative-fuel engineering. A dynamical approach to the interactions in polyatomic fluids long remained unattempted. An unconventional use of inelastic neutron scattering and simulations shows how sensitively anisotropic potentials can be discerned, and further reveals the molecular-pair geometry favouring the observed dynamics: a technique, first applied to methane, acting as a prototypical dynamical nanoscope of molecular liquids.