Neutron Inelastic Scattering Studies in Crystal Hydrates

Neutron inelastic scattering studies on polycrystalline samples of K2C2O4 · H2O, Ba(ClO3)2 · H2O, Li2SO4 · H2O, CaSO4 · 2H2O, CuCl2 · 2H2O, and BeSO4 · 4H2O have been performed at room temperature and 100°K with the aim to observe the librational frequencies in these hydrates. Deuterated salts were studied to confirm the librational modes. Within the experimental resolution, it is possible to observe two librational peaks in favourable cases. A definite assignment of these peaks could not be made even by comparison with other available data. Vibrational frequencies in K2C2O4 · H2O, Ba(ClO3)2 · H2O, and BeSO4 · 4H2O have been obtained from crystal energy consideration. From their comparison with the observed frequencies it may be seen that the nearest‐neighbour hydrogen bond is the dominant interaction for the calculations of the librational frequencies in these salts.