Dipolar order mediated (1)H → (13)C cross-polarization for dissolution-dynamic nuclear polarization

Magnetic resonance imaging and spectroscopy often suffer from a low intrinsic sensitivity, which can in some cases be circumvented by the use of hyperpolarization techniques. Dissolution-dynamic nuclear polarization offers a way of hyperpolarizing [Formula: see text] spins in small molecules, enhancing their sensitivity by up to 4 orders of magnitude. This is usually performed by direct [Formula: see text] polarization, which is straightforward but often takes more than an hour. Alternatively, indirect [Formula: see text] polarization followed by [Formula: see text] polarization transfer can be implemented, which is more efficient and faster but is technically very challenging and hardly implemented in practice. Here we propose to remove the main roadblocks of the [Formula: see text] polarization transfer process by using alternative schemes with the following: (i) less rf (radiofrequency) power; (ii) less overall rf energy; (iii) simple rf-pulse shapes; and (iv) no synchronized [Formula: see text] and [Formula: see text] rf irradiation. An experimental demonstration of such a simple [Formula: see text] polarization transfer technique is presented for the case of [1- [Formula: see text] ]sodium acetate, and is compared with the most sophisticated cross-polarization schemes. A polarization transfer efficiency of [Formula: see text] with respect to cross-polarization was realized, which resulted in a [Formula: see text] polarization of [Formula: see text] % after [Formula: see text] min of microwave irradiation and a single polarization transfer step.