Simulating a Gradient-Selective COSY experiment with 3 spins
Pulse Program: COSYGS
J couplings: 1-2=30Hz, 1-3=20Hz, 2-3=40Hz.
Parameters set manually: cnst21 = 20, cnst22 = 20, p0 = p1.
Gradient strengths are of same sign (cnst21 = cnst22 = 20%), hence N-peaks selection. Selection of P-peaks is illustrated below.
td1=128, td2=128, ns=1, p90=10 usec, PL=0 dB, SWp1=2.2 ppm, SWp2=2.2 ppm
Optimization: Selection of optimal number of layers and minimal sample length:
Step 1: Click on the "Simulation parameters" button in the Main panel. The Simulation Parameters panel will pop up:
Step 2: Click on "Salami optimizer" to start prerun:
Step 3: Click on "Update" to accept the displayed optimal simulation params:
Now close the Simulation params window and start the simulation by clicking on the ZG button.
Data Processing has to be done in the magnitude mode:
This is the resulting GS-COSY spectrum for 3 spins:
Here is how it looks in a 3D-View window.
This spectrum is a result of a selection of N-peaks.
Selection of P-peaks
For P-peaks selection, the gradients have to be of opposite signs,
e.g. cnst21 = 20, cnst22 = - 20.
All other paremeters remain same, including experimental parameters, optimal simulation params for gradients,
The resulting spectrum with P-peaks selection should look like:
No coherence selection:
When both N- and P-coherences are present (neither one is selected), the resulting spectrum looks like this:
This spectrum was obtained by setting cnst21 = cnst22 = 0. The axial noise is present because the number
of scans was 1 and no coherence selection was achieved.
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This manual page was designed by David Fushman & Olivier Walker.
Last updated 01/20/04
(c) Copyright 2004 by David Fushman, University of Maryland.