Single-input double-tuned circuit for double resonance nuclear magnetic resonance experiments

A single-input double-tuned probe was designed for double resonance nuclear magnetic resonance (NMR) experiments, in which high radio frequency power irradiations were achieved at two closely spaced frequencies (such as 26.1 MHz for Al27 and 28.4 MHz for Cu65). The efficiency of the probe for both nuclei was determined to be about 80%, compared to that obtained with a single-tuned probe. The probe was used successfully for Al–6527Cu SEDOR experiments to derive the internuclear distance between Al and Cu in Cu-ZSM-5 zeolite. The circuit is ideal for SEDOR-type double resonance NMR experiments, when high power irradiation is required for nuclei with closely spaced resonance frequencies.