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  PROCESSING YOUR DATA
 

Operations on the NMR spectrum.

To access help with a specific NUTS operation, click here.
       
  Peak picking
  The positions of peaks provide important clues to the identity of your sample. For example, hydrogens or carbons bonded directly to oxygen appear only in certain regions of the spectrum; aromatics are in another area. Such chemical-shift correlations are well-established for the nuclides that are commonly observed.
   
  To label the peaks in your spectrum with their chemical shifts, type pp. To simulate peak peaking in the figures below, place your mouse over the image (click here for larger screens). Note that the labels are very small; this will be fixed in the next step.
 
   
 

Note that this operation has not found all the peaks in the spectrum (it has only picked the ones marked in red). By default, NUTS selects only those resonances whose height is 10% of the maximum or greater. In many cases, this is not satisfactory. To check the relative height of the smallest peak you are interested in, simply hold down the left mouse button and position the resulting crosshairs over that peak; its height is shown in the lower right corner of the screen. To reset the threshold (minimum height) value, type mh in the command line. You will see a window like the one shown below. Enter the lower value in the highlighted box, click OK and type pp again to regenerate the peak list with the lower threshold. Move your mouse over the figure below to see the difference between a peak pick with a threshold of 10% versus one at 5% (click here for a larger version):
 
 
  Type fv to change the label font size (10 is a good choice). Change any font characteristics and click OK. To see the effect of a font-size change below, move your mouse into the image area (click here for larger versions):
 
   
 

To paste a list of the peak positions onto the spectrum, type CTRL-b. The result is shown below (click here for a larger version). This list will be included when you print the spectrum. To toggle the labels on and off, press CTRL-p.