a method for heteronuclear decoupling in fast magic - angle spinning nmr measurements comprises application of a decoupling rf - pulse sequence with a decoupling - field amplitude ν 1 i on spins of a first nucleus and of an excitation pulse on spins of a second nucleus , the sequence comprising m blocks of pulses , with m ≧ 4 , each block comprising an n - fold repetition of a pair of pulses with pulse width τ p and phases whereby τ p is equal for all pulses , whereby the phase of the pulse pair of the - th block is inverted with respect to the pulse pair of the i - th block , with i = 1 . . . m − 1 and i is an odd number , whereby the pulses within each pair are phase inverted , whereby a phase shift is carried out after each j - th block , with j is an even number . the efficiency of the inventive method compares favorably with cw , tppm , spinal and xix decoupling methods at medium and high rf amplitudes , particularly under rotary resonance conditions .