K. Venu et Vss. Sastry, PROTON SPIN-LATTICE RELAXATION IN THE DIMETHYLAMMONIUM GROUP, Zeitschrift fur Naturforschung. A, A journal of physical sciences, 48(5-6), 1993, pp. 713-719
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.