polarisation inversion and spin exchange at the magic angle frequency-switched Lee-Goldberg cross polarization A magic angle spinning NMR dipolar recoupling technique used to determine dipolar couplings between 1H and 13C nuclei. A FSLG sequence is used to remove homonuclear couplings (by spin-locking the 1H nuclei) and polarization transfer from the protons to the 13C via dipolar coupling manifests as a splitting of the detected 13C signal. FSLG-CP CHMO:0000929 frequency-switched Lee-Goldberg cross polarisation frequency switched Lee-Goldberg cross polarisation frequency switched Lee-Goldberg cross polarization