Kim, Y.J., et al., Polarization enhancement technique for nuclear quadrupole resonance detection. Solid State Nucl Magn Reson, 2014. 61-62: p. 35-8.
http://www.ncbi.nlm.nih.gov/pubmed/24882748
We demonstrate a dramatic increase in the signal-to-noise ratio (SNR) of a nuclear quadrupole resonance (NQR) signal by using a polarization enhancement technique. By first applying a static magnetic field to pre-polarize one spin subsystem of a material, and then allowing that net polarization to be transferred to the quadrupole subsystem, we increased the SNR of a sample of ammonium nitrate by one-order of magnitude.