⁸¹Br and ³⁵Cl NMR Investigation of Sodium, Silver, Halo-Sodalite Semiconductor Supralattices

⁸¹Br and ³⁵Cl NMR yields, respectively, bromide and chloride site-specific information pertinent to the structural and electronic properties of Na_8-n-pAg_nX_2-p-sodalite, semiconductor cluster supralattices, where X = Br, Cl; 0 ≤ n ≤ 8; 0 ≤ p ≤ 2. The ⁸¹Br and ³⁵Cl MAS chemical shifts and line shapes observed for encapsulated Na₄X and Ag₄X clusters within the sodalite cavities provide insight into the nature of the intracluster bonding (ionic-covalent character) and the extent of intercavity coupling. Substantial nuclear shielding is observed for encapsulated Ag₄X clusters in sodalite materials with high loading of Ag₄Br clusters, whereas no NMR signal is detected from silver-bromide clusters isolated within sodalite lattices. Spin-lattice and spin-spin relaxation measurements yield information on intracavity coupling and motion within the sodalite cages. The results enable one to explore the transition from isolated clusters to an expanded Ag₄X supralattice, through the compositional and temperature dependence of the NMR spectra of the sodalite halide anions.