Eliminating systematic error in multiple quantum diffusion measurements by bipolar gradient pulses

摘要

It is demonstrated that the systematic error in the measurements of self-diffusion coefficients using nuclear magnetic resonance multiple quantum spectroscopy method can be eliminated by bipolar composite gradient pulses that consists of a radio-frequency π pulse sandwiched by two gradient pulses with equal intensities but opposite polarities. Examples are given for heteronuclear double, triple and quadruple quantum diffusion measurements using the maximum quantum method. The effect of the gradient on the lock signal is clarified.