Second-Order Coupling Effects
When the shift difference between coupled nuclei is not much larger than J (delta-nu/J below ~10), first-order rules break down: multiplets lean toward each other (roofing), extra lines appear, and AB quartets replace clean doublets. Higher-field spectrometers restore first-order appearance by increasing delta-nu in Hz while J stays fixed.
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When the shift difference between coupled nuclei is not much larger than J (delta-nu/J below ~10), first-order rules break down: multiplets lean toward each other (roofing), extra lines appear, and AB quartets replace clean doublets. Higher-field spectrometers restore first-order appearance by increasing delta-nu in Hz while J stays fixed.
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