Steady-state free-precession in nitrogen-14 quadrupolar spin-system with axially symmetric electric field gradient tensor

The behaviour of nuclear quadrupolar resonance (NQR) signals in hexamethylenetetramine (C6H12N4) was studied using the steady-state free-precession (SSFP) pulse technique. Strong intensity variations of the steady-state signal as a function of the frequency offset and pulse spacing were observed, and these are associated with the interference of free induction decay and spin–echo signals in the steady state. Thus it was shown that the detected NQR signal may contain a spin–echo component, and the axial symmetry of the electric field gradient in the sample is not the reason why spin–echo signals were not observed in conventional pulse experiments for the same type of sample. Experimental results of applying some SSFP pulse sequences for nitrogen-14 NQR in (C6H12N4) are reported.