During nuclear magnetic resonance observations,<unk>  is the mechanism by which the longitudal component of the total nuclear magnetic moment vector (parallel to the constant magnetic field) exponentially relaxes from a higher energy, non-equilibrium state to thermodynamic equilibrium with its surroundings (the<unk> "). It is characterized by the<unk>  time, a time constant known as T1. There is a different parameter, T2, the<unk> -spin<unk>  time, which concerns the exponential<unk>  of the transverse component of the nuclear magnetization vector ( to the external magnetic field). Measuring the variation of T1 and T2 in different materials is the basis for some magnetic resonance imaging techniques.
Spin–lattice relaxation
Elastic recoil
Co-stimulation
Isobaric counterdiffusion
Uncoupling 
Fragmentation 
Haldane effect
Neural adaptation