| 摘要 |
Compensation rather than direct suppression removes the effects of acoustic ringing as encountered in pulsed nuclear magnetic resonance experiments. Single and double spin-echo excitation, combined with several alternative schemes for phase cycling both transmitter and receiver, is one type of compensatory technique. Another technique consists of acquiring free induction decay signals in pairs, with the second preceded by an inversion pulse a short time prior to the normal excitation pulse, and with the second acquisition acquired subtractively, assuring phase coherence of the signals and phase opposition and hence cancellation of the acoustic ringing. Phase cycling of the inversion pulse may also be employed in the latter technique to suppress acoustic ringing stimulated by the inversion pulse.
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