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 .nu..sub.1.sup.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.gtoreq.4, each block comprising an
N-fold repetition of a pair of pulses with pulse width .tau..sub.p and
phases whereby .tau..sub.p is equal for all pulses, whereby the phase of
the pulse pair of the (i+1)-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 favourably with CW, TPPM,
SPINAL and XiX decoupling methods at medium and high RF amplitudes,
particularly under rotary resonance conditions.