Bloch-Siegert shift compensated and cyclic irradiation sidebands eliminated, double-adiabatic homonuclear decoupling...

A Gaussian-shaped, offset-independent adiabatic decoupling is adopted to decouple 13CO from 13C alpha or vice versa for 13C- and 15N-double-labeled proteins, together with a compensating decoupling applied on the opposite side of the 13C alpha resonance frequency. In a quite broad range, the double-adiabatic decoupling eliminates efficiently the cyclic sidebands caused by direct irradiation of the adiabatic decoupling and reduces significantly the Bloch-Siegert shift. The remaining Bloch-Siegert shift, which is almost a linear function of offset, can be removed by a dilated evolution time. The decoupling sequence is also quite insensitive to the RF field intensity or inhomogeneity due to the reduced transverse components of RF field at 13C alpha, leading to an efficient decoupling even under unfavorable conditions.