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Abstract:
The problem of calculating dynamic deuterium quadrupole echo spectra in ordered systems in which exchange takes place between noninteracting nuclei with different quadrupole interactions and chemical shifts is solved. For the solution a specific set of basic spin I=1 matrices is chosen which allows casting the solution in a form having the same dimensionality as the Bloch–McConnell equations of spin I=1/2 nuclei. The theory is applied to two dynamic systems, viz., the ring inversion of cyclohexane and the Cope rearrangement in bullvalene, both in liquid crystalline solution. It is shown that even in ordered systems the time interval between the π/2 pulses in the quadrupole echo experiment may strongly affect the shape and intensity of the spectrum, thus providing an additional experimental variable for analyzing dynamic spectra. When large chemical shifts or off‐resonance pulses are involved, distorted spectra are obtained. This distortion can be removed by including π pulses in the quadrupole echo sequence which eliminate the dephasing effect of the chemical shift.
