Satellite structure of DNP enhanced C-13 NMR spectra in diamond

The P1 nitrogen defect centres in natural type Ia diamonds have been exploi ted in dynamic nuclear polarization (DNP) of the C-13 nuclei (1.1% abundant ) via the solid-effect. We have achieved sufficiently large C-13 polarizati ons in some diamonds to observe weak satellite lines in the C-13 NMR spectr a by using long microwave irradiation times. A study of the dependence of t he NMR spectra on the crystal orientation with respect to the applied magne tic field reveals that the satellite structure originates from the small fr action of C-13 nuclei that are involved in nearest neighbour dipole interac tions.