Spinning-sideband-free and spinning-sideband-only NMR spectra in spinning samples

Abstract

NMR spectra are needlessly confusing when spinning sidebands and isotropic peaks lie on the same curve. Qualitative analysis is impossible if these spinning sidebands cannot be distinguished from isotropic peaks and quantitative measurement is frustrated whenever any sideband overlaps any other peak. Resolving a spectrum into several curves, one containing only isotropic peaks, another only first higher frequency sidebands, still another only first lower, etc., eliminates these problems. These extra curves, which can be generated by an echo technique, do not require extra acquisition time. An ordinary echo spectrum refocused after two revolutions has the same S/N ratio as each curve in a separated spectrum which is made with the same total number of acquisitions.