Net magnetic moment per unit volume (a vector quantity) of a sample in a given region, considered as the integrated effect of all the individual microscopic nuclear magnetic moments.

(AFP) Adiabatic fast passage is a NMR technique of producing rotation of the macroscopic magnetization vector by shifting the frequency of RF energy pulses (or the strength of the magnetic field) through resonance (the Larmor frequency) in a time short compared to the relaxation times. Particularly used for inversion of the spins between high and low energy states with an excess of spins in the higher energy level. A continuous wave NMR technique used in e.g., MR spectroscopy.

Phenomenological (classical) equations of motion for the macroscopic magnetization vector. They include the effects of precession about the magnetic field (static and RF) and the T1 and T2 relaxation times.

A nonequilibrium state in which the macroscopic magnetization vector is oriented opposite to the magnetic field; usually produced by adiabatic fast passage or 180° RF pulses.

See Macroscopic Magnetization Vector.