Molecular clustering in a two-dimensional metal-ammonia solution.

Abstract

We have measured the in-plane x-ray diffraction pattern of the two-component ${\mathrm{K}}^{+}$ -N${\mathrm{H}}_{3}$ liquid layers in the ternary graphite intercalation compound K${(\mathrm{N}{\mathrm{H}}_{3})}_{4.33}$${\mathrm{C}}_{24}$. The measured pattern is in semiquantitative agreement with the scattering calculated for a random distribution of coplanar hard ${\mathrm{K}}^{+}$ and N${\mathrm{H}}_{3}$ disks, provided that the ${\mathrm{K}}^{+}$ ions are bound symmetrically to four N${\mathrm{H}}_{3}$ molecules. We show that the K-N${\mathrm{H}}_{3}$ layers constitute the two-dimensional structural analog of the well-known bulk three-dimensional K-N${\mathrm{H}}_{3}$ metal-ammonia solutions.