Optimizing the polarization matrix for ex situ dynamic nuclear polarization.

Although recent advances in dynamic nuclear polarization techniques have boosted the otherwise low sensitivity of NMR spectroscopy, the efficiency of the hyperpolarization process depends on the composition of the polarization matrix, in particular on the contact between the radical and the target molecule and the capability of the matrix to transfer polarization through spin diffusion. A concept for optimal matrix design is presented, applied to obtain two-dimensional heterocorrelated spectra of small drug-like molecules in 1-2 min after 90 min of hyperpolarization.