The librational spectra of water and heavy water in crystalline salt hydrates

Abstract

Infrared spectra are reported of nine mono- and dihydrates of alkali halides and alkaline earth halides. These spectra in the 300-600 cm-1 region are interpreted as arising from the librational modes of the bound water molecules as shown unambiguously by the frequency changes on substitution of deuterium oxide. Potential constants for this motion are given. Samples were prepared by evaporation of salt films in situ, and the method is seen to be of value for studying the limits of phase stability of unknown hydrates and related compounds. The number of bands observed in this region indicates for all cases studied the number of water molecules with different crystalline environments. © 1961.