NMR Imaging Using Second Order Quadrupole Broadened Resonances.
Theoretical and experimental results for NMR imaging measurements of powdered materials using the +(1/2) to -(1/2) transition of (1/2)-integerspin nuclei in the presence of a very large second-order electric quadrupolar broadening are presented. An "effective spin-(1/2)" formalism is developed to account for additional effects due to the presence of quadrupolar interactions comparable in size to the Zeeman interaction. A large (7.9 mT/cm-A, with a maximum current of approximately 20 A), rapid ( approximately 30 µs) pulsed linear gradient field is used with echoes and phase encoding techniques to obtain images in the limit gammaH1 is much narrower than the NMR linewidth. A one-dimensional projection of the second-order quadrupolar perturbed, 4-MHz-wide, +(1/2) left and right arrow -(1/2) transition for 63Cu in Cu2O powder is presented as an example. An experimental one-dimensional projection of a sample containing Cu2O and YBa2Cu3O6.7 is also presented. Copyright 1998 Academic Press.