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6 - NMR Polarization Measurement

Published online by Cambridge University Press:  03 February 2020

Tapio O. Niinikoski
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Summary

The principles of the continuous-wave (CW) NMR techniques is reviewed, as applied to the measurement of the nuclear polarization in polarized targets. The circuit theory of the series-tuned Q-meter is then described in detail in view of calculating precisely the CW NMR absorption signal and its integral, the signal-to-noise ratio, the probe coupling and sampling, and the signal saturation. Optimization of the series-tuned Q-meter circuit is discussed on the basis of the circuit theory. Improved Q-meter circuits will be reviewed, including the capacitively coupled Q-meter, the crossed-coil NMR circuit, and the introduction of quadrature mixer that enables the measurement of the real and imaginary parts of the RF signal simultaneously. Calibration and measurement of very small NMR signals then follows. We also treat the signal-to-noise issues, the electromagnetic interferences, and the NMR circuit drift issues.

Keywords

Transverse susceptibilityabsorption lineLiverpool series Q-metercircuit theorysignal-to-noise ratiosaturationoptimization of Q-meterTE calibrationsuperradiance.
Type
Chapter
Information
The Physics of Polarized Targets , pp. 245 - 282
Publisher: Cambridge University Press
Print publication year: 2020

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