Sensitivity enhancement of NMR spectra of half-integer quadrupolar nuclei in the solid state via population transfer

Abstract

Three population transfer techniques for improving the sensitivity of the central transition of NMR spectra from half-integer quadrupolar nuclei in the solid state are described. Two of the methods attempt to invert the populations of energy levels associated with the satellite transitions either by employing double frequency sweeps (DFS) or hyperbolic secant (HS) pulses. The third method, rotor-assisted population transfer (RAPT), is designed to saturate the satellite transitions. The effect of various experimental parameters on the resulting sensitivity enhancement is discussed. We trust that novice solid-state NMR spectroscopists interested in acquiring NMR spectra of half-integer spin quadrupolar nuclei will find these notes helpful. © 2005 Wiley Periodicals, Inc. Concepts Magn Reson Part A 26A: 47–61, 2005