The response of an isolated three‐spin system in solids to the pulse sequence 90°‐τ‐βφ; is investigated theoretically and experimentally. It is shown that in this system an echo occur both in the case of 90°‐τ‐90°90° (“solid” echo) and in the case of 90°‐τ‐β0° pulse sequences. In contrast to the “solid” echo the 90°‐τ‐β0° echo is observed not at 2τ but is shifted. The value and sign of this shift depend both on τ and on parameters characterising the geometry and orientation of the three‐spin system in a magnetic field. The experiments on polycrystalline (CH3)4NBr are in good agreement with theory.

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