Observation of Nuclear Relaxation of Nitrogen NQR Lines by Pulse Method

The relaxation equation of the nondegenerate nitrogen NQR lines which describes the case of the double 90° pulse method was derived from the rate equations. It showed that the spin-lattice relaxation of the resonance lines was characterized by two longitudinal relaxation times, T 1 s and T 1 l . From the same bases, the Alexander's repeating 90° pulse method was examined and was found that the term corresponding to T 1 s was smaller than in the former case. This difference between two pulse methods was verified with the NQR lines of N 14 in ethylenediamine. The temperature dependence of the relaxation time was also studied. It suggested that a molecular motion became active around 180 K.