Simulating a simple 1D experiment with 5 spins: Bromoethane
Pulse Program: zg 

Here we will give explicit step-by-step instructions for simulating a 1D proton spectrum for a spin system similar to that in bromoethane.


We assume that you have launched the Virtual NMR Spectrometer. Next, enter the spin system. This can be done manually, as illustrated below, or you can load the bromoethane spin system by pressing the ‘load’ button at the bottom of the main panel. When loading the spin system, be sure to select ‘spin system’ and not ‘all’.

STEP 1: Define the Spin System:


The spin system selected for this example consists of 5 protons, coupled with each other by a scalar coupling set to 7 Hz.
Use the pull-down panel to select 5 spins. 
Then click on the ‘spin setup’ button. This brings up the spin setup dialogue. Select the ‘Graph Mode’ button.

 

The graph mode is a user-friendly way to input chemical shifts and couplings. Pressing that button opens the graph mode window shown below.


Spin Setup: Graph Mode
The boxes numbered 1 through 5 represent the 5 spins in your spin system.

 

Enter 1.231 for the chemical shift value for the first nucleus. 
Here you can also define the type of the nucleus, its spin-relaxation rates, and the concentration of the molecular species that this atom belongs to -- here we use default values for all these parameters.

Now let us define resonance frequencies for all other nuclei. Click on the box for the first atom once to remove the blue highlight. 

 

Click on the box for the second atom (it should become blue).

 

Enter 1.232 for the chemical shift. Continue entering the chemical shifts for the rest of the atoms. Here’s a table of the chemical shifts: 

Atom

Chemical Shift

1

1.231

2

1.232

3

1.233

4

2.631

5

2.632

 

 

 

 

Remember to deselect one atom (click it so it isn’t blue) before moving to the next.

Once all of the chemical shifts have been entered, define scalar couplings between spins.

Deselect the atoms so that none are highlighted. Now select atom one (highlighting it) and then select atom two.

  

A line will form between them. Enter a coupling of 7Hz in the box under ‘J’.

Continue selecting pairs of atoms and Input 7 Hz for couplings for scalar coupling for all possible pairs of atoms. Once finished the ‘Graph Mode’ window will look like this:

Finally, click on the ‘Update’ button to save/input your data into VNMR. This takes you back to the ‘spin setup’ window.


STEP 2: Experimental Setup

Now we are ready to set up experimental conditions for the simulation.

Open Experimental Setup Panel and set experiment dimension to 1D:

 

Return to the Main Panel, select pulse sequence zg, and then click on the XLATE button to translate it. If the translation is successful, the ZG button will turn green.

 

Open Program Parameters panel and set pulse sequence parameters: in this case the only parameter that is not assigned and requires to be set is the recycling delay d1.

Program Parameters:


Set d1 to 1s.


Experimental Parameters:

Open Experimental Setup Window and set the carrier position (Op(1)=2 ppm in this example), the number of acquired experimental points you wish to simulate (td1 = 2048), and the desired spectral width (SWp1=2ppm) :All relevant entries in the program parameter window will be updated automatically.


STEP 3: Run Simulation

Click on the ZG (green) button -- this will start the simulation.

 


STEP 4: Data Processing.


Open Data Processing window, set zero-order phase correction PHC0=180 and check out the Phase Correction button.

Click on the Process button to process the simulated FID, and then on the REAL button to display real part of the resulting spectrum.


 The resulting spectrum should look like this one:



Here is a zoom on the up-field region of the spectrum:


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This manual page was designed by David Fushman & Charlie Geraghty.
(c) Copyright 2003 by David Fushman, University of Maryland.