A method of carrying out DNP on a sample with a molecular structure containing at least two J-coupled non-integer spin nuclear species, the method comprising hyperpolarizing the sample in a cooled, solid form while it is exposed to a homogeneous magnetic field of suitable strength; dissolving or melting the hyperpolarized sample; subjecting the sample to a polarization holding RF pulse sequence while the sample is exposed to a suitably homogeneous magnetic field of sufficient strength to ensure the spin's chemical shift is greater than the J-coupling, the pulse sequence causing the nuclear spin populations in the sample to be re-distributed between a plurality of energy levels in a non-equilibrium manner; and then, following a time less than the T1, relaxation time constant of the molecular species, causing the nuclear spin populations to transfer adiabatically to stable, equilibrium levels.