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

Abstract

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 (${T}_{\ensuremath{\lambda}}$) of appearance of side peaks associated with the removal of rotational degeneracy in ${\mathrm{H}}_{2}$ was found to shift to 2.18\ifmmode^\circ\else\textdegree\fi{}K for 86% ortho as compared to a value of 1.6\ifmmode^\circ\else\textdegree\fi{}K for the normal concentration. Our ${T}_{\ensuremath{\lambda}}$ 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\ifmmode^\circ\else\textdegree\fi{}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\ifmmode^\circ\else\textdegree\fi{}K. ${T}_{1}$ was measured roughly for the two concentrations. For $n$-${\mathrm{D}}_{2}$, ${T}_{1}$ was found to be 7.6\ifmmode\pm\else\textpm\fi{}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\ifmmode\pm\else\textpm\fi{}1 sec was found. The theory of Moriya and Motizuki gives 5 sec.