Fig. 3. Pulse sequence used for DNP/CP/MAS measurements. The conditions are as follows. Gyrotron: FU CW GOI apparatus was used, at an electron acceleration voltage of 18 kV and a beam current of 270 mA. NMR: a JEOL ECA 700 spectrometer was used with a 3.2 mm HC probe and a TPPM decoupling sequence.²².