⁸⁷Rb Dynamic-Angle Spinning NMR Spectroscopy of Inorganic Rubidium Salts

Five inorganic rubidium salts, RbCl, RbClO₄, Rb₂SO₄, Rb₂CrO₄, and RbNO₃, were examined using ⁸⁷Rb NMR spectroscopy. Significant line narrowing occurs under dynamic-angle spinning (DAS) compared to magic-angle spinning (MAS) or variable-angle spinning (VAS). From DAS spectra acquired at various magnetic field strengths, isotropic chemical shifts and isotropic second-order quadrupolar shifts were obtained. By simulations of single-site line shapes obtained from MAS-detected DAS experiments, complete chemical shift and quadrupolar parameters were determined for each of the three crystallographically distinct rubidium sites in RbNO₃.