I am using SIMPSON to simulate DQ signals generated by the pulse sequence SPC5. The input file of my simulation is modified from the input file of Post-C7, which is written in the original SIMPSON paper (Bak, M.; Rasmussen, J. T.; Nielsen, N. C. Journal of Magnetic Resonance 2011, 213 (2), 366–400.) My input file is as followed:
#Cb, Ca, C' in order
#parameters from Journal of Magnetic Resonance 164 (2003) 270–285 (for alanine)
spinsys {
channels 13C
nuclei 13C 13C 13C
dipole 1 2 -2147 0 69 111
dipole 2 3 -2117 0 0 0
dipole 1 3 -475 0 34 111
}
par {
spin_rate 25000
sw spin_rate/2.0
np 64
crystal_file rep100
gamma_angles 40
start_operator Inz
detect_operator -Inz
verbose 1101
}
proc pulseq {} {
global par
maxdt 1
#matrix set detect totalcoherence {2}
set rf [expr 5.0*$par(spin_rate)]
set t90 [expr 0.25e6/$rf]
set t270 [expr 0.75e6/$rf]
set t360 [expr 1e6/$rf]
reset
for {set i 0} {$i < 5} {incr i} {
set ph [expr $i*360.0/5.0]
pulse $t90 $rf $ph
pulse $t360 $rf [expr $ph+180]
pulse $t270 $rf $ph
}
store 1
acq $par(np) 1
}
proc main {} {
global par
fsave [fsimpson] $par(name).fid
}
I used "-Inz" first for detect_operator as in the original paper and got a build-up curve with intensity ~0.75 (as attached). But I want to obtain DQ signals so I change the detect_operator to be "–(I1p*I2p+I1m*I2m)", which stands for DQx. However I got a build-up curve with intensity ~0.0007, too low for the DQ conversion efficiency (as attached). I also tried "matrix set detect totalcoherence {2}" in the proc pulseq part to obtain DQ signals but had the intensity with similar intensity.
Does anyone know what’s wrong with my coding? Thanks in advance.
Hi!
Did you get a chance to solve your problem ? I am struggling with the simulation of DQ-DRAWS experimental results myself ... I would be thrilled if you could give me some insight if you managed to obtain good fits.
Thanks,
Ben
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