Nuclear quadrupole resonance

The nuclear quadrupole resonance spectroscopy (or tomography, in the English Nuclear quadrupole resonance, abbreviated as NQF) is one of the nuclear magnetic resonance imaging (MRI ) -derived ( depending on the procedure, imaging ) examination technique in materials science, safety engineering and medicine. It is used to represent atoms whose nuclei have a quadrupole moment ( for example, nitrogen -14, chlorine -35 or copper -63 ). In contrast to NMR, the NQF does not require a static external magnetic field, which is why this method is also sometimes called zero-field NMR ( zero- field NMR). A problem of nuclear quadrupole resonance spectroscopy is that many of the studied transition frequencies depend strongly on the temperature, which makes the use of nuclear quadrupole resonance spectroscopy outside the material science difficult. Another is the low signal strengths of the resonance radio signals.

Worldwide, there are several research groups are currently working because the nuclear quadrupole resonance spectroscopy for detection of explosives (mostly nitrogen compounds ) or drugs use. The first devices to detect landmines and bombs in baggage have been tested, the first such detectors have been already used in the 1996 Olympics in Atlanta. Another application is the measurement of the composition of water, oil and gas at oil wells in real time in order to control the delivery process better. The system itself is made of a radio wave transmitter, a coil ( quadrupole ) to generate the magnetic excitation field, and a radio wave receiver, which evaluates the NQR responses of the atoms. With a double or multiple resonance conditions of the resonance method further signals transmitted by different atoms are considered to (for example, TNT) to achieve even with compounds which supply very low resonance signals a good sensitivity.