Simulating a Gradient-Selective COSY experiment with 3 spins

Pulse Program: COSYGS

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Spin System:

J couplings: 1-2=30Hz, 1-3=20Hz, 2-3=40Hz.

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Program Parameters:

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.

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Experimental Parameters:

td1=128, td2=128, ns=1, p90=10 usec, PL=0 dB, SWp1=2.2 ppm, SWp2=2.2 ppm

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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.

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Data Processing has to be done in the magnitude mode:

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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.

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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, processing params.

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The resulting spectrum with P-peaks selection should look like:

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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.