Spin-locking in one pulse NMR experiment

The response of a spin system to a long (in comparison to spin–spin relaxation time T₂) radiofrequency pulse has been studied. We observed that the magnetization after the long pulse does not fall to zero at time tT₂ for both on-resonance and off-resonance conditions. The dependencies of the magnetization on frequency offset, linewidth and radiofrequency power are investigated, both theoretically and experimentally. The question of the effective field direction is also discussed.