ONE PULSE SPIN-LOCKING IN NQR

The response of a quadrupolar spin system in zero applied magnetic fie ld to a long rf pulse, for both single crystal and polycrystalline sam ples possessing broad Lorentzian:shaped resonance lines has been studi ed. The dependencies of magnetization on frequency offset, linewidth a nd power are investigated both theoretically and experimentally. The p roblem of the effective field direction in both single crystal and pol ycrystalline samples is also discussed. For a polycrystalline cuprous oxide (Cu2O) sample it is observed that the magnetization after a long pulse in on-resonance condition does not become zero for time t much greater than T-2, in agreement with theoretical results. It has also b een shown that the magnetization increases with increase in the width of the resonance line as well as with the decrease in the excitation p ower.