Phonon wings in inelastic neutron scattering spectroscopy: The harmonic approximation

摘要

The inelastic neutron scattering (INS) spectra of some ammonium halides and ammonium nitrate are analyzed in terms of the internal vibrations of the NH+4ion convoluted with multiphonon lattice modes up to the eighth term. Due to the low mass of this ion, most of the intensity of the internalhyphen;mode region of the INS spectra is in the lsquo;lsquo;phonon wings,rsquo;rsquo; differences between the salts in this spectral region being mainly due to differences in their latticehyphen;mode spectra. Refinement of the lattice Debyendash;Waller factor is included in the profile refinement of interatomic force constants.