Nuclear Magnetic Double Resonance Spectra of Three Spin Systems

The nuclear magnetic double resonance spectra of general three-spin systems are analyzed in detail by using a Hamiltonian that is made stationary by transformation to a rotating coordinate system, and by diagonalization of the complete Hamiltonian in the rotating frame. The double resonance spectra for ``field-sweep'' conditions are obtained from a plot of the ``frequency-sweep'' transition frequencies versus the frequency of the strong radio-frequency field. The double resonance spectra of the ring protons of 2-amino, 3-picoline are in close agreement with the results of the above analysis. It is also shown that the methyl protons in 2-amino, 3-picoline are coupled to the 4-proton.