NMR Full Form

Nuclei in a strong constant magnetic field are agitated by a weak oscillating magnetic field (in the near field) and respond by creating an electromagnetic signal with a frequency characteristic of the magnetic field at the nucleus. When the oscillation frequency matches the intrinsic frequency of the nuclei, which is dependent on the strength of the static magnetic field, the chemical environment, and the magnetic properties of the isotope involved, this process occurs near resonance; in practical applications with static magnetic fields up to about 20 tesla, the frequency is similar to VHF and UHF television broadcasts (60–1000 MHz). The magnetic characteristics of certain atomic nuclei give rise to NMR. NMR spectroscopy is commonly used to determine the structure of organic molecules in solution, as well as to research molecular physics, crystals, and non-crystalline materials. Magnetic resonance imaging, for example, is a common application of NMR (MRI). 

History About Nuclear Magnetic Resonance:

Isidor Rabi first characterised and measured nuclear magnetic resonance in molecular beams in 1938[2] by expanding the Stern–Gerlach experiment, for which he was awarded the Nobel Prize in Physics in 1944. Felix Bloch and Edward Mills Purcell, who shared the Nobel Prize in Physics in 1952, improved the technique for use on liquids and solids in 1946.

Yevgeny Zavoisky probably discovered nuclear magnetic resonance in 1941, long before Felix Bloch and Edward Mills Purcell, but regarded the findings as unreliable. On July 24, 1951, Russell H. Varian filed U.S. Patent 2,561,490 for “Method and means for correlating nuclear characteristics of atoms with magnetic fields.” In 1952, Varian Associates created the first NMR machine, the NMR HR-30.

Nuclear Magnetic Resonance Spectroscopy:

Due to the chemical shift of the resonance frequencies of the nuclear spins in the sample, NMR spectroscopy is one of the most used techniques for obtaining physical, chemical, electrical and structural information about molecules. Peak splittings between nuclei caused by J- or dipolar couplings are also beneficial. The functional groups, topology, dynamics and three-dimensional structure of molecules in solution and solid state can all be studied using NMR spectroscopy. Peak integrals can be used to assess composition quantitatively because the area under an NMR peak is usually proportional to the number of spins involved.

Spectroscopy Techniques in Nuclear magnetic resonance 

• Resonant frequency: It relates to the absorption’s energy as well as the signal’s intensity, which is related to the magnetic field’s strength. When put in a magnetic field, NMR active nuclei absorb electromagnetic radiation at a frequency characteristic of the isotope.
• Acquisition of Spectra: A nuclear magnetic resonance response is acquired after the sample is excited with a radiofrequency pulse. It’s an extremely weak signal that only sensitive radio receivers can detect.

Application of NMR:

Magnetic resonance imaging, a type of NMR, is widely utilised in medicine. NMR is mostly utilised in organic chemistry and in industry for chemical analysis. The approach is also used to determine the water-fat ratio in foods, monitor the flow of corrosive fluids in pipelines, and investigate molecular structures such as catalysts.

• Medicine:

Magnetic resonance imaging for medical diagnosis and magnetic resonance microscopy in research settings are the most well-known applications of nuclear magnetic resonance to the general public. It is, however, commonly employed in biochemical research, particularly in NMR spectroscopy such as proton, carbon-13, deuterium, and phosphorus-31 NMR. In vivo magnetic resonance spectroscopy or chemical shift NMR microscopy can also be used to collect biochemical information from living tissue (such as human brain tumours).

• Chemistry:

Chemists can determine the structure of many substances by analysing the peaks of nuclear magnetic resonance spectra. It can be an extremely selective approach, differentiating between many atoms within a molecule or group of molecules of the same type but differing only in their immediate chemical environment. NMR spectroscopy is used to clearly identify known and novel chemicals, and it is frequently utilised by scientific publications to confirm the identity of newly created molecules. For further information, see the entries on carbon-13 NMR and proton NMR.

Conclusion:

The study of molecules by recording the interaction of radiofrequency (Rf) electromagnetic radiations with the nuclei of molecules put in a strong magnetic field is known as nuclear magnetic resonance (NMR) spectroscopy.