The effect of added electrolytes on the electron spin resonance and optical absorption of solutions of the alkali metals in liquid ammonia.

A review of the development of the study of metal solutions is presented, with particular emphasis on the various models proposed to describe their physical properties. Electron spin resonance and optical absorption measurements are reviewed in detail. The electron spin resonance absorption of solutions of alkali metals in liquid ammonia has been studied as a function of the concentration of metal and of added alkali metal halides. When the concentration of metal is less than 0.01 molal there are small negative deviations in the g-factor for added chlorides and bromides, but very large deviations for added iodides, the shifts for a given salt molality being then a function of the cation. These shifts are enhanced at higher metal concentrations and higher temperatures, and are accompanied by a marked increase in the line width. The visible and near infra-red absorption spectra of some of these solutions have been measured and the appearance of a shoulder in the 12,500 cm-1 region has been confirmed. These results are discussed in terms of a specific interaction between unpaired electrons and iodide ions. A confined model for the solvated electron is developed by analogy with related systems, and is used to describe the spectral properties of electrons trapped in various media.