Spin–Spin Coupling
The splitting of an NMR signal into multiple lines caused by interaction with neighbouring non-equivalent nuclei.
Formula / equation
n + 1 rule
Unit
Hz
In depth
A proton with n equivalent neighbours gives a signal split into n + 1 lines with intensities following Pascal's triangle. The separation between lines, the coupling constant, is independent of field strength and reveals the geometric relationship between the coupled nuclei.
Examples in the real world
The ethyl group of ethanol showing a triplet for CH₃ and a quartet for CH₂.