Abstract
Neutron‐energy‐gain spectra have been measured in (NH4)2CO3, (NH4)2HC6H5O7, and NH4C2H3O2 at 20°C using the Brookhaven slow‐chopper facility. Each spectrum exhibits two peaks that are characteristic of optical modes. The spectra of ammonium carbonate and ammonium citrate are similar to those of the body‐centered‐cubic lattice phase of the ammonium halides in which the ammonium ion has torsional and translational optical vibrations.