Nuclear Spin Relaxation in Cs Metal

The characteristic nuclear-magnetic-resonance parameters, Knight shift, line shape and width, and relaxation times have been measured in cesium metal from the melting point to 1.6°K. The nuclear spin relaxation time $T_1$ is inversely proportional to the temperature from 300 to 7°K, with $T_{1}T=0.135\mathrm{}\pm 0.01$ sec °K. For temperatures below 7°K, the relaxation shows another contribution of unknown origin. The Knight shift increases linearly with temperature down to 4°K, following the line previously measured by Gutowsky and McGarvey at higher temperatures. Diffusion narrowing of the magnetic-resonance line is observed at 190°K, but the strong electron-nucleus interactions preclude good diffusion-constant measurements.