The evolution of magnetization and the wave sequence during the SQUID NMR experiment. (a) The magnetization is nearly along the axis with the prepolarization field of along the axis and the measuring field along the direction; (b) the magnetization is along the axis after turn off the ; (c) a pulse field is applied to rotate the magnetization to direction; (d) the NMR signal is processed about the measuring field direction; and (e) the pulse sequences with , , and and the NMR signal as a function of time.
(a) FID of the NMR signal of 20 ml of water in a lower measuring field of after 2500 averages. The corresponding NMR spectrum is shown in (b). The prepolarization is 10 mT, the polarizing time is 5 s, and the time delay is 0.1 s.
The SNR and the linewidth of NMR spectrum as a function of the field strength of prepolarization field in a static magnetic field of .
Normalized NMR intensity as a function of the polarizing duration time,
Normalized NMR intensity as a function of the delay time, .
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