Electron Spin Resonance Studies of the Onset of Metallic Character in Metal-Ammonia Solutions

Asymmetric electron spin resonance spectra are described for moderately concentrated solutions of the alkali metals in liquid ammonia as functions of temperature, metal concentration, and concentration of added electrolytes. Both the asymmetry and the linewidth increase markedly above a critical temperature, corresponding to a thermal promotion of electrons from trapping sites to a conduction band. The g factor of the asymmetric resonance is strongly dependent on the concentration of added iodides.