A study of orientational ordering in solid deuterium

Nuclear magnetic resonance (NMR) studies were performed on samples of solid deuterium with para concentrations X in the range 0.05 X 0.07 at temperatures between 0.032 and 3.0 K and at a Larmor frequency of 5.88 MHz. This range of temperatures and concentrations includes the first order transition to the long range orientational ordered state. The spin-lattice relaxation times for both ortho (1 = 2) and para (1 = 1)D2 species were measured by the intensity of solid echoes generated by the pulse sequence. In addition, the solid echoes themselves were digitized which, through the use of the fast Fourier transform, provided both the lineshapes of the two species, and the second-moments M sub 2 of their absorption lines. At all concentrations below which the transition to a long range ordered phase does not occur, the temperature dependence of the lineshape, secondmoment, and spin-lattice relaxation times is quite smooth.