Helium-cooling and -spinning dynamic nuclear polarization for sensitivity-enhanced solid-state NMR at 14Â T and 30Â K

► A new helium-cooling and -spinning DNP SSNMR system was developed. ► 395-GHz microwave was generated using a high-power, frequency-tunable gyrotron. ► DNP enhancement of ≈50 was observed at B0 = 14 T and T ≈ 30 K under MAS. ► Results highlight potential of DNP SSNMR technique under very high field conditions.