NMR Spinning Sideband and Spin Echoes. Imaging of Couette Flow

The sidebands generated by a cylindrical sample spinning in a linear gradient under Hahn spin-echo conditions are examined experimentally and theoretically. Explicit expressions are developed for the phase and intensity of the magnetization as a function of time. When the signals are sampled stroboscopically with the echo time matched to multiples of the rotation period, a standard spinning-sideband pattern is observed. Intermediate pulse delays result in a decrease in sideband intensity and nonlinear phase distortions across the pattern. The stroboscopic sampling technique is applied to Couette shear flow to selectively detect slices from the fluid on the basis of angular velocity. The imaged annular slices may then be analyzed spectroscopically.