Nuclear Magnetic Resonance of Solid Hydrogen (67-86% Ortho) and Solid Deuterium (33% and 55% Para)

Nuclear magnetic resonance studies on solid hydrogen (${\mathrm{H}}_2$) of ortho concentrations from 67% to 86% and of solid deuterium (${\mathrm{D}}_2$) with para concentrations of 33% and 55% are reported. The method of Cunningham, Chapin, and Johnston was used to produce the high concentrations ortho ${\mathrm{H}}_2$ and para ${\mathrm{D}}_2$. The temperature ($T_{\lambda }$) of appearance of side peaks associated with the removal of rotational degeneracy in ${\mathrm{H}}_2$ was found to shift to 2.18°K for 86% ortho as compared to a value of 1.6°K for the normal concentration. Our $T_{\lambda }$ versus concentration data were found to join smoothly to the previous lower concentration work of Sugawara et al. In addition an interesting hysteresis phenomenon was observed for ${\mathrm{H}}_2$. It was noted that the temperature of appearance of the side peaks when the ${\mathrm{H}}_2$ is cooled is some 0.15°K lower than the temperature of their disappearance when the temperature is slowly raised. In the case of deuterium, no peaks were observed for either 33% or 55% para ${\mathrm{D}}_2$ at temperatures down to 0.9°K. $T_1$ was measured roughly for the two concentrations. For $n$-${\mathrm{D}}_2$, $T_1$ was found to be 7.6±3 sec. This compares well with the theoretical value of 8 sec given by Moriya and Motizuki. For 55% para-${\mathrm{D}}_2$, a value of 3±1 sec was found. The theory of Moriya and Motizuki gives 5 sec.