Nuclear Spin Relaxation in Cs and Rb Metals below 77°K

Abstract

Experimental values of the product $T_{1}T$ have been determined in the low-temperature range for the nuclear spin systems ${\mathrm{Cs}}^{133}$ and ${\mathrm{Rb}}^{87}$ in Cs and Rb metals. Anomalous results previously reported for Cs at low temperatures have been shown to arise from thermal gradients in experimental samples and are spurious. The experimental values which obtain from 1.4 to 77°K are $T_{1}T=0.13\mathrm{}\pm 0.01$ sec°K for ${\mathrm{Cs}}^{133}$ and $T_{1}T=0.11\mathrm{}\pm 0.01$ sec°K for ${\mathrm{Rb}}^{87}$. Spin-echo measurements of the intrinsic $T_2$ for ${\mathrm{Cs}}^{133}$ in our samples give $T_2=1.5\mathrm{}$ msec. This number agrees with determination of intrinsic linewidths by others by independent techniques.