Enhanced NMR detection appts. for explosives - has transmitter and receiver connected to RF coil surrounding sample holder near magnet

摘要

The apparatus comprises a magnet to produce a magnetic field acting on the comingled first and second atomic elements of the samples which magnetic field has a intensity. A RF coil acts at right angles to the magnetic field acting on the sample. A transmitter is connected to the RF coil to produce a transmitted pulse burst of specified frequency, amplitude and duration acting on the sample. A receiver connected to the RF coil forms an output voltage proportional to the nuclear magnetic resonance response of the nuclei of the first element. A device is for controlling the magnetic field intensity of the magnet to achieve a level selected such that the resonant frequency of the first element in the nuclear magnetic resonance mode is approximately equal to the second element nuclear quadrupole resonance so that the NMR signal at the receiver is enhanced.