An Introduction to Nuclear Magnetic Resonance Spectroscopy

Professor Jonathan Parr By submitting this essay, I attest that it is my own work, completed in accordance with University regulations.—Andrew Yang An Introduction to Nuclear Magnetic Resonance Spectroscopy by Andrew Yang Nuclear Magnetic Resonance Spectroscopy, or NMR Spectroscopy, is a powerful nondestructive research technique that uses the magnetic properties of nuclei to investigate the corresponding molecules and their interactions. The phenomenon of nuclear magnetic resonance was first measured by Isidor Rabi in 1938 using molecular beams, and in 1946 Felix Bloch and Edward Mills Purcell expanded the technique to study liquids and solids, for which they were award the 1952 Nobel Prize for Physics. NMR Spectroscopy has become one of the most widely used spectroscopic techniques, seeing application from the investigation of organic molecules to the resolution of protein structure in studies of structural biology. NMR Spectroscopy is based on detecting transitions between nuclear spin states, where nuclei in a magnetic field absorb and re-emit electromagnetic energy at specific resonance frequencies. NMR spectroscopy can generally be reduced to two fundamental steps: (1) alignment of the nuclear spins in a constant applied magnetic field, and (2) perturbation of the alignment with an applied frequency pulse. This is possible due to the fact that nucleons possess spin angular momentum, which can give rise to magnetic moments, meaning that their energies depend on their orientation in an applied magnetic field. The energy of a magnetic dipole in an