The Scattering of Neutrons by Liquid Water
Neutrons are a unique probe for the study of molecular dynamics. Their mass is comparable to the mass of the nucleus and their velocities undergo a Doppler shift when they are scattered from moving nuclei. The associated energy change is easily measurable if the initial velocity of the neutrons is small enough. Nuclear reactors provide a source of suitable neutrons, a typical energy E being 25 meV with associated de Broglie wavelength of 1.8 Å. This wavelength is comparable to the interatomic distances in condensed matter and so the change in momentum on scattering is sensitive to the structure of the scattering system. Thus, the distribution as a function of angle of neutrons scattered from a system of nuclei gives information on the spatial distribution of the nuclei, while the distribution of neutron energies at any one angle gives information on the motion of the nuclei.
KeywordsLiquid Water Spectral Density Function Pair Distribution Function Light Water Incoherent Scattering
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