A new technique for cross polarization in solid-state NMR compatible with high spinning frequencies and high magnetic fields

The idea of integrated cross polarization which has been utilized for electron-to-nucleus polarization transfer is applied to nucleus-to-nucleus polarization transfer. Instead of using a π2 pulse followed by a π2 phase-shifted locking pulse like in the conventional cross polarization, irradiation with a single phase is applied together with adiabatic frequency sweep from far off-resonance toward on-resonance. This is capable of locking individual spin packets even in the presence of considerable spectral distribution and/or line broadening. Thus, this technique can provide efficient polarization transfer for spin species having large chemical shifts and experiments in high static fields.