Spectroscopic studies of aqueous solutions.

The work of this thesis was carried out in order to try to understand more fully the structure and solvating properties of water. Several forms of spectroscopy were used to gain information on the effect of non-electrolyte and electrolytes on the structure of water. The spectra of water and aqueous solutions are generally regarded as being uninformative as the bands are broad and insensitive to additives. However, the work in this thesis overcomes the problem by isotopic dilution of H2O by D2O and by greatly lowering the temperature of the solutions to form 'glassy solids'. The bands become better resolved and information can be obtained from the appearance of sub-bands. A water molecule is capable of forming four hydrogen-bonds, tetrahedrally disposed, but this ideal situation does not exist in liquid water and hydrogen-bonds will be constantly breaking to give OH free and Lone Pair groups. The presence of the OH free groups was monitored in the near infrared as a function of temperature and added electrolytes and nonelectrolytes. In the infrared, at low temperatures, bands can be identified due to OH groups bonded to additives. Using these results, this thesis attempts to explain the manner in which water solvates and also to calculate the percentage of OH free groups which are present in pure water at room temperature. Results compare favourably with those of other workers although conclusions often differ. Ultraviolet spectroscopy was used to study the CTTS spectrum of the iodide ion in methyl cyanide when solvated by water, methanol and ethylene glycol. Equilibrium constants were obtained from the spectra which gave good agreement with those of other workers.