An Improved Diffusion-Ordered Spectroscopy Experiment Incorporating Bipolar-Gradient Pulses

We report a study of BPPs (bipolar pulse pairs) in PFGNMR (pulsed field gradient NMR) that shows a drastic reduction in eddy currents for short (≃1 millisecond), closely spaced (<1 ms) gradient pulses. Improved resolution is obtained in LED-DOSY with reduced settling times (T e ) so that samplzs with shorter values of T 1 can be studied. The three gradient prepulses can be eliminated so that temperature control is improved and convection currents are reduced. Finaly, the 180° RF pulses in combination with the alternating gradients serve to restrict the observable volume so that only regions having a homogeneous B 1 field and a constant gradient are observed.