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MAGNETIC NUCLEAR RESONANCE
| Dynamic polarisation
The nuclear magnetization, proportional to the Erath magnetic field B0 is too week to be measured.
The Abragam Effect allows an amplification of the nuclear signal by a coupling between the spins of the protons of a solvent and the spins of free electrons of a free radical in solution. 
Hyperfine structure of the free radical energy spectrum | The energy spectrum of the free electron of the selected free radical shows four levels of energy in presence of a field B0. and due to its coupling with the spin of a nitrogen nucleus, the electronic resonance can be achieved using a RF field.
A suitable selection of two frequencies for the same solution is done to allows a positive protonic polarization (1_2) for the lower frequency and a negative protonic polarization (1_4) for the upper frequency. | |
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