Pulsed and continuous wave nuclear magnetic resonance study of the complex molecular motion in t-butylammonium bromide

Abstract

The proton n.m.r. second moment and spin–lattice relaxation times T₁ and T_1p are measured against temperature for polycrystalline t-butylammonium bromide. Analysis of the experimental data yields activation parameters for the complex molecular motion which is taking place: methyl and NH⁺₃ group reorientation, t-butyl group reorientation and reorientation of the cation as a whole. A broad minimum in T₁ and two well resolved minima in T_1ρ observed at lower temperatures are interpreted in terms of the dynamical inequivalence of the methyl groups in the cation, which is confirmed by analysis of far-infrared spectra recorded at various temperatures.