Shown below are the pulse sequence and coherence transfer pathway for triple-quantum filtered COSY.

Grouping the first two pulses together, devise a six-step phase cycle which will select the required pathway (i.e. step the pulse phase in increments of 60° and determine the correct receiver phase shifts). Once this pathway has been selected, is any further phase cycling necessary?
Without further detailed calculations explain what other pathways are selected by your phase cycle, and comment on whether or not they are a matter for concern in practical spectroscopy.
Write an alternative six-step phase cycle for the above experiment in which just the phase of the last pulse, and the receiver, are shifted; you will need receiver phase shifts which are not multiples of 90°.

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