Nsutite, proton dynamics and momentum distributions

Recent work on γ-MnO2 using Inelastic Neutron Scattering shows the presence of several types of proton in the lattice. These types of proton include; first, a hydride-like H+ associated with specific lattice sites; second, a molecule-like (H+)4 which charge compensates Mn4+ vacancies; third, a free H+ component. The idea of free is developed into the measurement of momentum distributions. A Neutron Compton Scattering spectrometer, suitable for the measurement of atomic momentum distributions, is outlined very briefly. The first observation of the atomic momentum of a tunnelling proton is presented.