This phenomenon is called nuclear magnetic resonance, and it is used to look at the structural properties of a material’s atomic makeup. As a technique, it is widely used in organic chemistry, analytical chemistry, biology, quality control, medical analysis, and non-destructive testing. NMR applications include:

• Atomic-resolution structure determination of large biomolecules
• Determining the residual structures of unfolded proteins and the structures of folding intermediates
• Determining the chemical properties of functional groups in biomolecules
• Studying weak functional interactions between biomolecules
• Detecting hydrogen bonding interactions
• Identifying drug leads and determining the conformations of the compounds bound to enzymes, receptors, and other proteins
• Metabolite analysis
• Chemical identification and conformational analysis of chemicals
• In materials science research of polymer chemistry and physics

An essential factor for NMR is that the resonance frequency of a substance is directly proportional to the magnetic field that is applied to it. Typically, with the strong magnetic fields generated by the superconducting magnets, or coils, used in modern NMR instruments, proton resonance frequency falls within the radio-wave range, anywhere from 100 MHz to 800 MHz, depending on the strength of the magnet.

NMR imaging techniques can produce high-quality images because of this, and NMR spectroscopy is used to study molecular physics by providing information on the structure of organic molecules.

The nuclei produce an electromagnetic signal by placing an atom in a strong magnetic field and then exposing it to an oscillating magnetic field produced by the magnets. The signal made shares qualities with the magnetic field at the nucleus and provides a lot of information about the properties of the atom.

This process results in nuclear spin, where the atom is excited for a specific amount of time before returning to its equilibrium state by a process known as T1 and T2 relaxation. Measuring this relaxation behavior provides more information about the material being tested. There are three main steps involved in the NMR process:

• Alignment (polarization): A constant magnetic field is applied to the nuclear magnetic spins of the molecule.
• Perturbation: The oscillating magnetic field is applied to and perturbs the nuclear spins of the molecules. The oscillating magnetic field is also referred to as a radio-frequency pulse.
• Detection: The detection coil picks up the NMR signal due to the specific precession spin rate of the nuclei in the magnetic field.