Magnetic resonance imaging of electroconvection in a polar organic solvent

Molecular motion in the polar organic solvent nitrobenzene induced by an el ectric field is studied by magnetic resonance imaging. Rf pulse sequences t hat correlate images obtained at two different times under conditions of bo th continuous and pulsed electric fields are introduced. The resultant imag e correlation spectra indicate that the time scale of motion in a 9.6 kV/cm electric held is tens of milliseconds. Comparison of the results to an ana lytic solution for the Fokker-Planck probability function for one-dimension al bounded diffusion yields an electric field dependent effective diffusion coefficient for perdeuterated nitrobenzene of D = 1.08 x 10(-5) cm(2)/s (3.33 x 10(-3) cm(4)/kV(2)s) E-2 at room temperature. Characteristics of th is electroconvection and its consequences for combining multidimensional nu clear magnetic resonance with electrical orientation are also discussed. (C ) 2000 Academic Press.