Off-Resonance Decoupling

Off-Resonance Decoupling Definition:

In NMR spectroscopy, a technique in which only the one-bond couplings are observed. CH3
groups appear as quartets, CH2 groups appear as triplets, CH groups appear as doublets, and quaternary carbon atoms appear as singlets.

Off-Resonance Decoupling Explained:

Decoupling is the process of removing specific kinds of J-coupling interactions in order to simplify a spectrum or identify which pairs of nuclei are involved in the J-coupling. In order to understand how decoupling works, you must first Understand what causes J-coupling in the first place. Decoupling is accomplished by irradiating at the frequency of one nucleus (Hb) with continuous, low-power RF. This irradiation causes the Hb nucleus to “flip” from the lower energy (aligned) to the higher-energy (opposed) state and back again very rapidly. Because the NMR “time scale” or “shutter speed” that it is taken which  is relatively slow (in this case on the order of 1/J or more than 100 milliseconds),