In short, the peaks we can observe in a 1H-NMR are just a small fraction of the actual transition resonances which are not observable because of the limited digital resolution. Nonetheless, there is an additional limiting factor, and whose importance is generally underestimated which has to do with the generally large number of transitions in 1H-NMR spectra. spatial uniformity of the applied magnetic field, etc).

On the other hand, there are instrumental shortcomings (e.g. For example, if T2 is about 1 second, the peak linewidth at half height cannot be less than 0.32 Hz (remember, line width at half height = 1 / (pi * T2) = 1 / 3.1415 = 0.32) no matter how powerful is our NMR instrument or the field homogeneity. First, we have the natural line width limitation imposed by the T2 (spin-spin relaxation). Overlapping peaks and new ways to get around it will be the subject of this post.Īs it is well known, there are two principal factors limiting the resolution power in a spectrum. Nevertheless, I have often found that many organic chemists do not always try to get the most out of 1H-NMR spectra (which is the cheapest experiment), in particular when some multiplets are complex to interpret (strong coupling) or when peaks overlap prevents valuable information to be detected in some multiplets.

Coupling constants mestrenova