1. n. [Formation Evaluation]

In a nuclear magnetic resonance (NMR) measurement, the loss of synchronization of hydrogen atoms precessing at different speeds about the static magnetic field. When the signals from individual atoms are not synchronized, they are out of phase and the total signal is reduced. The dephasing occurs either because of inhomogeneities in the static magnetic field or through molecular processes. Dephasing due to inhomogeneities is known as the free-induction decay and is corrected by the CPMG sequence. Molecular dephasing is known as transverse relaxation.

See: echo spacing,  free-induction decay,  longitudinal relaxation,  nuclear magnetic resonance,  nuclear magnetic resonance measurement,  transverse relaxation