Enhanced double quantum signals in nuclear magnetic resonance

Abstract

A suggestion by Yatsiv for enhancing the strength of double quantum signals in high resolution nuclear magnetic resonance by use of radio-frequency sidebands is examined and shown to be practical. The theory shows that double quantum techniques can be extended to weakly coupled systems of nuclei (including systems of nuclei of different isotopic species). The AX part (with J _AX=5·4 c/s, δ_AX/2π=99·2 c/s) of the proton magnetic resonance spectrum of maltol (3-hydroxy-2-methyl-γ-pyrone) serves to confirm experimentally the quantitative theoretical treatment for weakly coupled systems. An enhancement factor of eight was observed as can be seen in figure 2.