NMR IMAGING USING 2ND-ORDER QUADRUPOLE BROADENED RESONANCES

Theoretical and experimental results for NMR imaging measurements of p owdered materials using the +1/2 to -1/2 transition of 1/2-integer spi n nuclei in the presence of a very-large-second-order electric quadrup olar broadening are presented. An ''effective spin-1/2'' formalism is developed to account for additional effects due to the presence of qua drupolar interactions comparable in size to the Zeeman interaction. A large (7.9 mT/cm-A, with a maximum current of approximate to 20 A), ra pid (approximate to 30 mu s) pulsed linear gradient field is used with echoes and phase encoding techniques to obtain images in the limit ga mma H-1 is much narrower than the NMR linewidth. A one-dimensional pro jection of the second-order quadrupolar perturbed, 4-MHz-wide, +1/2 <- ---> -1/2 transition for Cu-63 in Cu2O powder is presented as an examp le. An experimental one-dimensional projection of a sample containing Cu2O and YBa2Cu3O6.7 is also presented. (C) 1998 Academic Press.