PURE NUCLEAR QUADRUPOLE RESONANCE IN TRIETHYLENE DIAMINE

A detailed study of the pure nuclear quadrupole resonance of 14N in solid triethylene diamine is described. The resonance frequency, spin-lattice relaxation time (T1), and the free-induction decay time (T2) were measured as a function of temperature from 80°K to the plastic transition at 351°K. From 200°-300°K T1 is dominated by hindered molecular rotations about the trigonal axis of the molecule modulating the dipolar interaction with the protons. The activation for this reorientation was found to be 8.17 kcal/mole, in reasonable agreement with NMR results of Smith. The linewidth is discussed in detail and indicates an acentric structure of the molecule. Effects of the approach to the plastic transition are evident in all the three quantities measured but could not be interpreted in detail.