THE EFFECT OF ELECTRIC-FIELD GRADIENT ASYMMETRY ON MOTIONALLY AVERAGED SPIN-1 POWDER PATTERNS

The effect of an asymmetric electric field gradient tensor on anisotropic NMR spectra of spin-1 nuclei is investigated for fast molecular rotations and 2-site jump processes. When molecular rotations are fast, continuous, and complete, the peak-to-peak splitting of motionally averaged spin-1 NMR spectra can depend significantly on the inherent electric field gradient asymmetry, eta, for eta greater-than-or-equal-to 0.05. Parameters describing low-symmetry molecular motion which are extracted from fitting experimental data depend strongly upon eta. One implication of these phenomena is that even the modest electric field gradient asymmetry around deuterons in covalent bonds can contribute considerably to motionally averaged lineshapes, especially when molecular motions are not highly symmetric.