The Effect of a Second Radiofrequency Field on High Resolution Proton Magnetic Resonance Spectra

Abstract

A theory is developed to predict the energy levels and transition intensities of the A proton in an AX-type high-resolution spectrum when a strong radiofrequency field is applied near the X proton resonance. The results are expressed in a graphical form that clearly illustrates the two possible methods of investigating the decoupled A resonance pattern, the `field sweep' and the `frequency sweep' methods. Experimental results for dichloroacetaldehyde show close agreement with these predictions for both methods of investigation. Instrumentation based on a suggestion of Primas (1961) has been used to maintain a very high degree of stability in the electromagnet field during the `frequency sweep' experiments.