Below NMR pulse program describes the z-filter with cogwheel phase cycling for (1D and 2D) +3QMAS experiment applied to nuclei with 3/2 spin.
Fig. 1: Z-filter 3QMAS NMR pulse sequence and coherence transfer pathway.
The echo amplitude and the antiecho amplitude have the same sign.
This NMR pulse program is for Bruker Avance spectrometers.
A pure absorption 2D spectrum is obtained with the shearing transformation.
; YM-3qzfil1_5-cog24p.av ; cog24(0,4,19,7) = cog24(23,3,18,6) ; receiver phase for cogwheel with standard values: ; ph31 = (360/24)*6*m = 90*m ; ; I = 3/2 3QMAS pulse program ; 3-pulse experiment with zero quantum filter: ; excitation(±3Q) - conversion(0Q) - tau - 90° selective - ACQ(-1Q) ; 90° selective pulse should be determined first using Hahn-echo, ; determination by single pulse excitation is also possible ; Then optimise P2 and finally P1, 2 or more iterations for P1 and P2 ; may be needed. ; For processing shearing transformation may be requested, ; use AU program xfshear ; ;ns : 24*n ;d1 : recycle delay ;p1 : excitation pulse at pl11 ;p2 : conversion pulse at pl11 ;p3 : 90 degree selective pulse at pl13 ;pl1 : = 120 db ;pl11 : power level for excitation and conversion pulses ;pl13 : power level for selective pulse ;d4 : = 20u, delay for z-filter ;d0 : = 3u ;in0 : 1 rotor period for synchronised experiment ;td1 : number of t1-experiments ;FnMODE : States ;MC2 : States ze ; clear memory, new data replace old data, ; switch AD converter to replace mode, ; perform DS before next acquisition, 1 d1 ; recycle delay, 10u pl11:f1 ; 10 microsecond delay, ; set high power in f1 channel, (p1 ph1):f1 ; high-power excitation pulse, d0 ; delay between pulses, t1 increment, (p2 ph2):f1 ; high-power conversion pulse, d4 pl13:f1 ; set low power in f1 channel, (p3 ph3):f1 ; low-power 90° pulse, go=1 ph31 ; signal acquisition, ; loop to 1, ns times for averaging, d1 mc #0 to 1 F1PH(ip1, id0) ; delay for disk I/O, store signal, ; increase FID number, ; delete memory data, ; do not perform dummy scans ; with next acquisition, ; increment p1 pulse phase by 360°/12 ; for States procedure, ; increment time d0 by in0, exit ; end of the pulse program ph10=(24) 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 ph1=(12) ph10*23 ; excitation pulse phase ph2= ph10*3 ; conversion pulse phase ph3= ph10*18 ; 90° selective pulse phase ph31= ph10*6 ; receiver phase :(360/24)*6*m=90*m
This pulse program remains valid for the third pulse with strong amplitude for better excitation of off-resonance nuclei.