The infrared spectra of the hydrates of ammonia, NH3⋅H2O and 2NH3⋅H2O at 95 °K

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Abstract
The monohydrate and the hemihydrate of ammonia have been grown from the liquid and characterized by their x‐ray powder diffraction patterns at ∼100 °K, which are reported. Infrared spectra of samples mulled in liquid propane, propylene, or Freon 13 at 95 °K are reported from 4000 to 400 cm−1 and a preliminary assignment is made. The previously reported infrared spectra of these compounds are not correct, undoubtedly because the method of preparation did not yield the correct compounds. The spectra are consistent with the reported structures except that limited proton‐disorder may occur in the monohydrate and that the lengths of the two types of O–H⋅⋅⋅N bond in the hemihydrate may differ by ∼0.04 Å instead of the reported 0.02 Å. The frequencies of O–H stretching vibrations in O–H⋅⋅⋅N bonds of length 2.775 to 2.84 Å at 100 °K are in the range 2910 to 3125 cm−1.