NMR cogwheel phase cycling determination with web tools: Amplitude-modulated z-filter MQMAS sequence

Our recent method based on the use of web tools (XML and XSLT) for constructing cogwheel phase cycles is extended to the selection of two symmetrical coherence transfer pathways in the case of an amplitude-modulated z-filter MQMAS sequence. For all spins (I=3/2, 5/2, 7/2 and 9/2) and all MQ experiments we compare cogwheel phase cycling with the traditional “nested” phase cycling. The principal difference in the number of phase cycling steps lies in the use of digitizer phase. For nested phase cycling, this number depends on the use of reference receiver phase or digitizer phase, while cogwheel phase cycling does not. As an illustration we consider the case of a±3QMAS experiment for spin I=7/2 system applied to cobalt-59 in [Co(NH3)6]Cl3 powder. We also explore the selection of two non-symmetrical coherence transfer pathways in the case of an amplitude-modulated shifted-echo MQMAS sequence.