The homonuclear decoupling (homodecoupling) allows to simplify multiplet structures by irradiating a specific ¹H resonance. Inambiguous assignments and measurement of ¹H-¹H coupling constants can be performed by analyzing the resulting residual multiplets.

Easy implementation on AVANCE spectrometers.

During an homoedecoupling experiment, a conventional ¹H spectrum is recorded. From a second channel, low-power irradiation is applied on a predefined frequency during the acquisition period (see homodecoupling building block).

The homodecoupling experiment can be acquired, processed and plotted in a fully automated way. Minor changes from a predefined parameter set are required. Important parameters to consider are the offset and the power level of the irradiation. It is useful to have a calibration of the field strength delivered from the decoupler in order to optimize the required selectivity and to minimize Bloch-Siegert shift effects.

For further details on practical implementation on AVANCE spectrometers see Tutorial: Homodecoupling

The homodecoupling experiment affords a conventional ¹H spectrum in which the irradiated signal is missing and all protons J-coupled to this irradiated ¹H will show residual multiplet structure (the corresponding J coupling splitting has also been removed). Comparison between multiplet structure of the conventional ¹H spectrum and the homodecoupling spectrum allows to measure and to assign coupling constants values.
See Homodecoupling Test

A 2D COSY experiment can be a more useful alternative to trace out all J-connectivities from a single spectrum.