PROTON SPIN-LATTICE RELAXATION IN THE DIMETHYLAMMONIUM GROUP

A model for the spin lattice relaxation time of the protons of dimethy lammonium in the Redfield limit and common spin temperature approximat ion is developed. The three fold reorientations of the methyl groups, the rotation of the whole molecular group around its two fold symmetri c axis and possible correlations among these motions are considered. T he effect of these processes on the dipolar interactions among the pro tons within the same molecular group is taken into account. The result ing relaxation rate is powder averaged and used to explain the experim ental data in literature on [NH2(CH3)2]3Sb2Br9. The analysis shows tha t dynamically inequivalent groups exist in this compound and that the effect of proposed correlation among the different motions on the fina l results is negligible.