A two-dimensional experiment that separates decoupling sidebands from the main peaks

Broadband decoupling techniques generate undesirable cycling sidebands. The new two-dimensional technique described here allows separation of these sidebands from the main peaks by spreading the sideband responses in the indirectly detected dimension (F(1)) according to their frequency separations from the parent peaks, leaving the main resonances at zero frequency in F(1). This trace at zero frequency shows a thousandfold suppression of the residual sidebands, making possible the detection of very weak signals from dilute constituents of the sample. The experimental results can be displayed as one-dimensional "quiet decoupling" spectra without any significant loss of sensitivity. The new technique (DESIRE-decoupling sideband resolved spectroscopy) is simple, robust, and straightforward to implement.