Single-Crystal X-Ray Diffraction Study of β Nitrogen

Abstract

Three-dimensional x-ray diffraction data have been collected from single crystals of nitrogen at 50°K. The observed general condition, l=2n for hh2h̄l reflections is in agreement with the previously assigned space group, P63/mmc, and there are two molecules in the unit cell. The data agree equally well with two nearly physically indistinguishable models, in each of which the molecular centers form a hexagonal closest packed (hcp) lattice. In one, the molecule is precessing about the z axis passing through its center, at an angle of 54.5±2.5° between z and the N–N bond, while in the other the nitrogen atoms are statistically distributed among the 24-fold positions with the molecular axis again at an angle of 54.5° relative to z.