Diagonal Suppresion

Diagonal Suppression (Not available in Mnova Lite):

In the 1D NMR Processing section, we described the real-time frequency domain processing concept. Diagonal Suppression of homonuclear 2D experiments represents another example of this concept. This technique is typically carried out in the mixed time-frequency domain (interferogram). However, this is something you do not need to know in Mnova. You can suppress the diagonal while the transformed spectrum is on the screen.

For example, the figure below shows a 2D magnitude spectrum:

To suppress the diagonal, just select Diagonal Suppression command under the 'More Processing' scroll down menu:

This option offers a couple of well known traditional algorithms (Convolution and Shifted Convolution) as well as a new, in-house developed algorithm based on Wavelets to remove the diagonal from homonuclear spectra. Once you select the 'diagonal suppression' on the FT scroll menu, a dialog box like this will open:

As you can see, you can select the desired algorithm and also the selectivity of the diagonal supression. In the case where you choose the in-house algorithm based on Wavelets, you will be able to set the 'Dyadic Levels' and the 'Daubechies Coefficients'.

In this example we will select the Wavelet method; and this is the resulting diagonal-free spectrum.

Note that in the figure above there are two pages, the first one containing the 2D spectrum with its original diagonal, and the second one after the diagonal has been removed.