Pulsed spin-locking of spin-3/2 nuclei: ³⁹K-NQR of potassium chlorate

A model was developed for predicting a locked signal under a series of refocusing pulses for Nuclear Quadrupole Resonance (NQR) of spin I=32 and tested with a powder of KClO₃. This work represents the first direct NQR detection of the ³⁹K line of potassium chlorate. The characteristic time constants, T₁,T_2e and T₂^∗, were measured to determine the detectability of potassium chlorate via ³⁹K-NQR. The echo train T_2e was found to be strongly dependent on the refocusing pulse-spacing and weakly dependent on the refocusing pulse strength. The optimal angles of the excitation and echo pulse for a pulse train were also determined, as well as, the resonance-frequency dependence on sample temperature.