Polarization enhancement of NQR signals for explosive detection

This paper presents first experiments on using Zeeman polarization-enhanced nuclear quadrupole resonance (NQR) method in detecting explosive substance pentaerythritoltetranitrate (PETN). The NQR signals were detected on nitrogen nuclei at room temperature using a multi-pulse spin-locking sequence after the sample was kept in a very inhomogeneous magnetic field. The dependence of enhancement factor on the time of protons polarization in the magnetic field was studied.