Spin-echoes in nitrogen-14 quadrupolar spin-system with axially symmetric electric field gradient tensor

Abstract

The behaviour of the magnetisation in the spin-1 system with the axial symmetry of the electric field gradient (EFG) tensor was analysed theoretically. The behaviour of the NQR signals in hexamethylenetetramine (C 6H 12N 4) was also studied experimentally using the pulse NQR technique and sensitive equipment. It was shown that the axial symmetry of the EFG in a sample could not be the reason why spin-echo signals were not observed in conventional pulse experiments for the same type of sample. A very short spin–spin relaxation time T 2 seems to be the reason of that. The signal-to-noise ratio was sufficient for measuring T 2 in C 6H 12N 4, which had not been reported earlier. Experimental results of applying certain pulse sequences to the 14N NQR in a sample are also presented.