Transverse-Magnetization Recovery in the Rotating Frame

Abstract

The transverse relaxation of ${\mathrm{F}}^{19}$ nuclei in Teflon in the rotating frame at exact resonance has been studied by using rf fields large compared to the local field in this solid. Various pulse sequences are explored which serve to trace out the decay of the magnetization in the rotating frame and, further, to recover the magnetization lost under the action of secular dipolar terms and of the inhomogeneity of the rf magnetic field. It is found theoretically, and partially confirmed experimentally, that the rotary free-induction decay can be refocussed even after the spin system has presumably attained a steady state in the rotating frame, contrary to the assumption of the spin-temperature approximation.