Infrared Spectrum, X-Ray Diffraction Pattern, and Structure of Ammonium Fluoride

The infrared spectrum of ammonium fluoride and deutero-ammonium fluoride at —195°C and 25°C is shown to be explicable in terms of ``essentially'' Td symmetry requiring that the axial ratio (c/a) be 1.63. New x-ray-lattice parameter measurements show this to be true. A comparison of the spectrum of NH4F with other ammonium salts indicates that broad bands do not necessarily accompany strong hydrogen bonds.