Proton assisted insensitive nuclei cross polarization

This Communication presents a solid-state NMR N-15-C-13 polarization transfer scheme applicable at high B-0 and high MAS frequencies, requiring moderate rf powers and mixing time (1-6 ms). The sequence, PAIN-CP, involves the abundant nearby protons in the heteronuclear recoupling dynamics and provides a new tool for obtaining long distance N-15-C-13 contacts. It should be of major interest for biomolecular structural studies.