Single crystals of K(CN${)}_{\mathit{x}}$${\mathrm{Br}}_{1\mathrm{-}\mathit{x}}$ enriched in ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$ have been studied by ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$ NMR. Because of the anisotropic chemical shift, the NMR frequency spectrum of the orientational glass state reflects the distribution of cyanide orientations. By studying the spectrum at many crystal orientations, the orientation distribution function ${\mathit{P}}_{\left(\mathrm{\Omega }\right)}$ has been determined for x=0.50 and 0.20. The probability function is largest along [100] directions, intermediate in [110] directions, and nearly zero along [111] axes. The NMR determined ${\mathit{P}}_{\left(\mathrm{\Omega }\right)}$ is presented graphically and in terms of the Kubic harmonic functions. The NMR results are in sharp contrast to molecular-dynamics calculations but agree with neutron scattering data for x=0.53.

• Received 17 October 1989

DOI:https://doi.org/10.1103/PhysRevB.41.6234