Librational Modes of Crystal Water in Hydrated Solids

Abstract

The first paper on librational modes (LMs) of water in hydrated solids appeared in 1956 [l], although some earlier papers mentioned them in the context of other studies [2–4]. No detailed review is available, but articles in some books on water [5, 6], hydrogen bonding [7], and infrared (IR) spectra of inorganic and coordination compounds [8, 9] give partial coverage to the subject. The present paper reviews the up-to-date information and understanding on the topic. No attempt has been made to create a comprehensive bibliography or to discuss and evaluate individual papers. The emphasis is on the development of methodology and systematics. In several cases, work on a particular substance is discussed because it brings out the salient features which are representative of many other salts. The review, which covers work published to June 1979, is limited mainly to IR [including attenuated total reflection (ATR)] and Raman studies, with some coverage of neutron inelastic scattering (NIS) and nuclear magnetic resonance (NMR) studies. Methods used primarily for the study of structure (e. g., X-ray, electron and neutron diffraction) are not covered.