Electron Spin Relaxation in Metal-Ammonia Solutions

The electron spin resonance relaxation times ( T 1 and T 2 ) for solutions of lithium, sodium or potassium in liquid ammonia have been measured by transient methods for a resonant frequency of 9340 Mc/s over the temperature range -75 °c to 80 °c. T 1 and T 2 are equal except for potassium for which T 2 is shorter than T 1 by an almost constant amount over the whole temperature range. From the equality of T 1 and T 2 an upper limit on the correlation time of the electron spin interaction with 14 N nuclei of 3.5 × 10 -12 sec at -33.3 °c is established. An estimate is made of the effective number of 14 N nuclei in interaction with the electron spin which excludes the `cavity' model for these solutions. For the dilute solutions of lithium, ζ T 1 , where ζ is the shear viscosity of pure liquid ammonia, is independent of temperature whereas for sodium ζ T 1 / T is about constant.