Fig. 2.

Simulated dependencies of ¹³C–¹³C polarization transfer efficiencies on RF field strength and the resonance frequency difference, for the following experiments: a fpRFDR_xy16, b CORD_xy4, and c CORD–RFDR. A C₂H₂ spin model was used for the simulations; the MAS frequency was 40 kHz and the magnetic field strength 14.1 T. The fpRFDR and CORD mixing times were 2.4 and 150 ms, respectively. The colored dashed lines in (d–f) indicate the polarization transfer pathways operational in U-¹³C,¹⁵N-MLF tripeptide during each experiment