Studies of ultraslow diffusion ofNe21in solid neon using adiabatic magnetization in the rotating reference frame

Nuclear spin-lattice relaxation times $T_1$ in the laboratory frame and $T_{1\mathrm{p}}$ in the rotating frame have been measured for ${}_{}{}^{21}{}_{}{}^{}\mathrm{Ne}$ in polycrystalline solid neon. Adiabatic demagnetization in the rotating reference frame measurements of $T_{1\mathrm{p}}$ extend previous NMR studies of atomic diffusion in neon to lower temperatures. No deviation is observed from Arrhenius behavior between 12 and 23 K. The coefficient of atomic self-diffusion is found to be $D={0.15}_{-0.02\mathrm{}}^{+0.03\mathrm{}} \exp \left[\frac{-(944\mathrm{}\pm 6)}{\mathrm{RT}}\right]$ ${\mathrm{cm}}^2$/sec and the monovacancy approximation appears to be valid for diffusion in solid neon. Quadrupolar relaxation via an anharmonic Raman process describes the temperature variation of $T_1$ from 22 to 11 K. Below 9 K both $T_1$ and $T_{1\mathrm{p}}$ become nearly independent of temperature.