Vibrational spectroscopy of some inorganic single crystals.

This thesis contains the results of studies by single crystal vibrational spectroscopy of several materials. In an introduction the essential facts necessary for an understanding of the construction and nature of crystals in relation to single crystal vibrational spectroscopy are summarised. A review of i.r. reflectance spectroscopy is given as this was the major technique used in this research. A brief description of the Raman process is also given as well as methods of crystal growth used for this work. Single crystal i.r. and Raman spectra for topaz are reported. A complete assignment is given for the v(Si-O) region; at lower frequencies there is a more or less continuous range of modes and any assignments in this regian must be tentative. Some fragmentary data for spodumene are reported. Single crystal i.r. and Raman spectra for AICI3.6H2O are reported and, together with data collected from the deuteriate, enable an assignment to be given. The assignment takes note of normal coordinate analysis calculations, deuteriation shifts, and factor group components, as well as solution data. An assignment for the modes due to water motions is given by comparison with previous assignments for mono-and di-aquated complex ions. Far-i.r. spectra of HgCl2 HgBr2 are reported at both ambient and low temperatures. For HgCl2 the trans- latory modes have been identified from the fundamental modes predicted by theory, all of which have been observed. All the fundamental modes of HgBr2 have been observed and assigned to symmetry species. Far-i.r. spectra of three complex halides with the CsNiCl3 structure are reported at ambient temperature. The results agree well with those reported previously for mulls and an unambiguous assignment is given. Far-i.r. spectra of five square-planar complexes are reported at both ambient and low' temperatures. Complete assignments for K2PtBr4, (NH4)2PtCl4 and (NH4)2PdCl4 ware given for the first time. In the case of K2PtBr4 V4 and V7 are accidentally almost degenerate at ambient temperature. The lattice mode region of the ammonium salts has been assigned; the breadth of the central region of i.r. mulls of these compounds is due to three bands occurring in close proximity. The occurrence of low temperature features in the chlorides has been confirmed, the possible origin of these modes is discussed. A simplified factor group analysis scheme is given for the 80 diperiodic groups which lack periodicity in the third dimension. Examples of the use of the Tables are given. Listings of computer programs used for i.r. reflectance analysis are given in the appendices.