The infrared absorption spectra in the out-of-plane
bending (v₂) region of potassium nitrate were studied for
three phases. Several types of sampled were used: nujol
mulls, fused samples, and N¹⁴-N¹⁵ isotopic mixtures. The
existence of three of the reported polymorphic phases was
confirmed by the spectra. The transitions between phase...