NMR = Nuclear Magnetic Resonance is the resonance that occurs when a nucleus
(usually hydrogen, but any nucleus that has non-zero spin will work) is placed in a
magnetic field and is 'swept' by a radio frequency that causes the nuclei to
This causes the radio frequency to be absorbed, which is what is measured.
MRI = Magnetic Resonance Imaging is a more complex application of NMR in which the
geometric source of the resonances are detected and deconvoluted by Fourier
ESR = Electron Spin Resonance is also a resonance phenomenon, except in this case
it is the spin of an unpaired electron that is in resonance, rather than a nuclear
Answered by: Vince Calder, Ph.D., Physical Chemist, retired
'One cannot help but be in awe when he contemplates the mysteries of eternity, of life, of the marvelous structure of reality. It is enough if one tries merely to comprehend a little of this mystery every day.'