NMR in lithium metal: thermal mixing

We present a calculation of the thermal mixing rate t~ 1 between nuclear Zeeman and dipolar reservoirs in the presence of large rf fields. We applied this calculation to slow-motion diffusion in lithium metal. In particular, we measured the rotating frame spin-lattice relaxation time Tl p as a function of Hx and observed the transition between the regions of validity of low-field and high-field theories. Furthermore, we demonstrated that this transition occurs when Tlp ~ rm.