DOUBLE-QUANTUM COHERENCE DETECTION IN A SPIN-3/2 SYSTEM EXCITED BY 2 CONSECUTIVE PULSES

The density matrix describing the evolution of a spin-3/2 system excited by a spin-lock sequence is calculated from the thermal equilibrium to the end of the second radio-frequency pulse by taking into account only the first-order quadrupolar interaction. It is shown that certain combinations of spin-lock and rotary-echo sequences with appropriate phase cycling detect the double-quantum coherence and the magnetization independently. Moreover, applying the progressive saturation method would alloy the study of spin-lattice relaxation. Some predictions are illustrated with Li-7 nuclei in a single crystal of LiTaO3.