Two-Dimensional Multiple-Quantum MAS NMR of Quadrupolar Nuclei. Acquisition of the Whole Echo

Abstract
Multiple-quantum MAS NMR experiments have recently been used to remove second-order quadrupolar broadening from the central transition of half-integer nuclear spins (I = 3/2, 5/2, etc.). The advantages of using symmetric or whole echo acquisition in these experiments are discussed and it is shown that this approach to pure absorption-mode lineshapes is especially suitable for use in combination with a split multiple-quantum/single-quantum evolution (t₁) period.