COMPOZER-based longitudinal cross-polarization via dipolar coupling under MAS.

We propose a cross polarization (CP) sequence effective under magic-angle spinning (MAS) which is tolerant to RF field inhomogeneity and Hartmann-Hahn mismatch. Its key feature is that spin locking is not used, as CP occurs among the longitudinal (Z) magnetizations modulated by the combination of two pulses with the opposite phases. We show that, by changing the phases of the pulse pairs synchronized with MAS, the flip-flop term of the dipolar interaction is restored under MAS.