The infrared spectrum of ammonia hydrate: Explanation for a reported ammonia phase

A number of anomalous spectra of solid NH3 deposited from the vapor phase have appeared in the literature. These spectra have been ascribed to a new phase of NH3. In the experiment reported here these anomalous spectra were reproduced by depositing a thin film from a mixture of gaseous NH3 and H2O and annealing this film at a temperature of 162 °K. The thin film spectra showed excellent agreement with recent data on NH3⋅H2O. The anomalous ’’NH3’’ spectra are, therefore, seen to be caused by H2O contamination of solid NH3 with formation of NH3 hydrate.