Spin-Lattice Relaxation Time of a Dilute Solid Solution of Orthohydrogen in Hydrogen Deuteride

The statistical theory of nuclear magnetic resonance (NMR) is applied to compute the spin-lattice relaxation time of hydrogen deuteride with very low concentration of $o$-${\mathrm{H}}_2$. We find that the theory fits experimental data of Hardy and Gaines if the crystal field due to the zero-point motion of HD is more general than that assumed by Kranendonk and Sears. For extremely low concentration (∼0.01%) of $o$-${\mathrm{H}}_2$, our results are compared with the recent data by Rubins, Feldman, and Honig, and a general quantitative agreement is reached. A detailed comparison is not possible, because of insufficient information, but we have pointed out the essential experimental information needed to check the calculations given here.