Knowledge Bank

High resolution neutron inelastic scattering spectra in the region below $250cm-1$ have been obtained from solid HCl at temperatures corresponding to the low temperature ferroelectric phase, the high temperature disordered phase and the recently $reported1$ (120$\circ K$--98.4$\circ K$) intermediate phase. These data were obtained utilizing a time-of-flight spectrometer with a crystal monochromator. The resolution of this instrument is sufficient to enable previously unresolved structure to be observed. The low temperature phase data are compared to cross-sections calculated by using a full lattice dynamical $model2$ and good agreement is obtained.