Suggested Workflow for J-Resolved Spectra
In most 2-D experiments the scales on orthogonal axes both measure a chemical shift. They are called correlation experiments. J-Resolved Spectroscopy is different; here one of the scales measures the coupling constants. The processing workflow is similar, albeit with a few additions. At the end, the projection along f-2 contains a single peak per nucleus, as if they had been decoupled, while the traces along f-1 contain the multiplet patterns. The total number of peaks is the same as in the 1-D spectrum, but they are resolved across two dimensions.
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Open the Edit > Metadata dialog.
In the first column (f-1), set the nucleus to “0-J” and the observe frequency to 1 MHz.
This first step is a matter of taste and you can skip it. After the suggested modification, you'll have no problem with the projections and the scales. -
Fourier Transform twice.
Use a squared sine bell (shift = 0°) in both dimensions. Normally you'll want to increase the resolution: zero-fill in both dimensions, but more in f-1 than in f-2. The classical version of the experiment is not displayed in absorption mode: select “Magnitude” in the final FT. -
Open the Reference Spectrum.
You certainly have the traditional 1-H spectrum of the same sample, possibly acquired with an identical spectral width. Keep it open. We'll use it as an external projection and also to reference the frequency scale of our 2-D plot. Now let's return to the 2-D spectrum. - Calibrate the Frequency Scale.
After the second FT, the X dimension of our 2-D experiment corresponds to the J-dimension. Open the dialog: Format > Axes & Scales. Set the central frequency to zero. Click on “set”. Move to the last panel and transpose the plot. Return to the first panel to calibrate the other scale. You can use the command “Copy Reference from: select an open window” and select the 1-D reference. This trick will work if the frequency range is identical in both cases. - Tilt.
Each component of each multiplet appears at its natural frequency, given by the sum of the chemical shift and of the coupling constants divided by 2. However, we want all components to be realigned at the central frequency of each multiplet, removing the J contribution. The command for the task is Process > Symmetrize > Tilt. - Symmetrize.
After tilting, the peaks acquire an oblique shape. You can make them symmetric and sharper with Process > Symmetrize > Sym J resolved. Like all non-linear methods, it removes a lot of nasty signals and artifacts but could, at the same time, create its own artifacts. This operation is optional, and often convenient. - Add the external projection.
Use the Overlay Manager. - Zoom and Cut.
Hide the empty regions around and between the important peaks, using the tools “zoom” and “cut”. - Adjust the Contour Plot.
Open the dialog Format > Levels & Colors. Set the spacing to approximately 1.2, remove the negative levels, increase the number of positive levels until all splittings become visible.