A study of the spin-echo spin-locking effect in multi-pulse sequences in 14N nuclear quadrupole resonance

Experimental evidence of observing a rather unusual spin-locking spin echo (SLSE) effect in the fields of two multi-pulse sequences (ϕ0)x − (τ − ϕx − 2τ − ϕx − 2τ − ϕ−x − 2τ − ϕ−x − τ)n and (ϕ0)x − (τ − ϕx − 2τ − ϕy − τ)n in 14N nuclear quadrupole resonance is presented. It was demonstrated that the SLSE effect is observed only in the even pulse intervals of both sequences. All experiments were carried out at room temperature on a powder sample of NaNO2. A theoretical description of the effect is given.