The subject of hindered molecular motion is reviewed here, not only from a theoretical point of view but also with some interesting applications. The authors are Professor Ferid Bashirov of the Kazan State University and Professor Nail Gaisin of the Kazan State Technological University in the Tatarstan Republic of the Russian Federation.
They present a stochastic theory of classical hindered motion of small molecules, and molecular fragments, in molecular and ionic crystals; and they develop an extended angular jump model, which is intermediate between the rotational diffusion and fixed angular jump models. The theory takes into account the various point group symmetries of both the molecular motion and of the site, including any distortions. Applications are given in the description of NMR relaxation rates and the broadening of spectral lines, especially in Raman, Rayleigh and neutron spectroscopy, as well as incoherent neutron scattering, of single-crystals and powdered specimens. The text is supported by many striking three-dimensional graphs, by several extensive tables and by numerous references to the scientific literature. Chemical compounds, specifically discussed, include ammonium chloride, lithium nitrate, sodium nitrate, rubidium hydrogen sulphate and zircon. We hope that this very substantial work will be useful to all those working in this field.
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