VI. Homonuclear Decoupling

This section will explain what homonuclear decoupling does. Examples of homonuclear decoupled spectra taken on the Unity+300 and VXR-S 400 are given in Figure VI-1.

Homonuclear decoupling is a double-resonance experiment because it uses two RF fields to affect magnetically active nuclei. Homonuclear decoupling involves applying a second ¹H RF field to cause selective saturation of a nucleus A while observing all other nuclei in the molecule; B, C, D, etc. If nucleus A is spin-coupled to nucleus B and if the second RF field is strong enough, the result is that A is effectively prevented from spin-spin interacting with B. The observed B nucleus spectrum will appear as if it is not coupled to A. The A resonance commonly appears as a tall spike or glitch as a result of this experiment. In Figure VI-1, if the triplet is decoupled, the quartet collapses to a singlet. Similarly, if the quartet is decoupled, the triplet collapses to a singlet.