Solid-state spin-echo Fourier transform NMR of ³⁹K and ⁶⁷Zn salts at high field

We have used a two-pulse spin-echo sequence (with appropriate phase cycling) to obtain relatively undistorted second-order powder pattern spectra of the nonintegral spin quadrupolar nuclei ³⁹K and ⁶⁷Zn, in solids. Using the spin-echo approach, central transition breadths of up to approximately 100 kHz may be readily investigated. Results on 18-crown-6 ether · ³⁹KNO₃ and ³⁹K⁺ · monensin^- yield e²qQ/h values of 1.80 and 3.20 MHz, with η = 0.37 and 0.52, respectively. For ⁶⁷Zn(OAc)₂ · 2H₂O, e²qQ/h = 5.3 MHz and η = 0.87 have been obtained. The spin-echo approach should permit investigation of a wide variety of nonintegral spin quadrupolar nuclei in solids using high-field Fourier transform methods.