ORIENTATIONAL ORDER AND ROTATIONAL-DYNAMICS OF THE AMIDE IONS IN POTASSIUM-AMIDE - II - QUASI-ELASTIC NEUTRON-SCATTERING

The ionic molecular crystal potassium amide (KNH2) was investigated by means of quasielastic incoherent neutron scattering (QNS).:In the ori entationally disordered cubic and tetragonal high-temperature phases a s well as in the ordered monoclinic phase reorientational motions of t he amide ions (NH2-) are resolved in a frequency range of three orders of magnitude. The QNS spectra are well explained by reorientational m odels for each phase. Furthermore, the results are compared to structu ral data and findings of other spectroscopic methods. Finally, a consi stent picture of structure and dynamics of all three phases of potassi um amide is obtained. (C) 1998 American Institute of Physics.