Nuclear Quadrupole Relaxation and Overhauser Effect

Nuclear quadrupole relaxation occurs only during nuclear spins with I 

The nuclear Overhauser effect (NOE) refers to the transfer of magnetization between spins coupled by the dipole-dipole interaction in a molecule. The dipole-dipole coupling is related to intemuclear distance and it undergoes Brownian motion in a liquid. In the process of equilibrium, the population (a-spins and (3-spins) transfers from one species to another species. For that reason, the NOE is a nuclear relaxation. It is a change in the intensity of one response to the other under perturbation. 

The NOE is observed in the interaction between H H neighbors, H— neighbors and also unpaired electrons, that is, in the presence of paramagnetic materials such as oxygen atoms. 

The chemical shift— for functional groups and the nuclei environment 

The J couplings— for the torsion angles to obtain information about the molecular backbone and side chains if any 

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