Different approaches have been proposed to minimize/suppress the undesired diagonal peaks in NOESY-type spectra, in order to observe helpful NOE cross-peaks near to diagonal. Some references:

• Clean 3D 1H-15N TROSY-NOESY experiment ( 00JMR195-142 and 02CONC1 )
• 99JMR499-140
• 3D NOESY-[1H,15N,1H]-ZQ TROSY ( 99PNAS9607 )
• 2D and 3D TROSY-NOESY experiments ( 99JB377-14 )
• 97MRC877

Other experiments have been also proposed to minimize strong and undesired diagonal signals, as for instance, the HCCH experiment ( 01JB69-19 and 00JMR171-144 ).