Cross-correlations in NMR

Abstract

The phenomenon of nuclear magnetic resonance (NMR) involves placing magnetically active nuclear spins embedded in a gas, liquid or solid phase in a constant, large and uniform magnetic field, causing a splitting of magnetic energy levels.Energy can be absorbed by these spins from a resonant radiofrequency (RF) field causing transitions between these levels. Immediately following this absorption, the spins start to exchange this energy among themselves and also pass it on to other degrees of freedom, that is, the spins start to relax. Relaxation is central to the NMR phenomenon as a necessary prerequisite for its detection. It is also used as a probe for obtaining information on the local environment of the spins and about the dynamics of the molecules in which the spins are embedded.