SINGLE-FREQUENCY-SHIFTED AND MULTIPLE-FREQUENCY-SHIFTED LAMINAR PULSES

A simple method of generating frequency-shifted pulses is demonstrated for any spectrometer which is capable of generating an extended series of amplitude- and phase-modulated RF pulses. This method can be combined with existing methods of selective excitation to produce single- or multiple-frequency-selective pulses, or can be combined with "hard" pulses for experiments in which it is desired to place the center of excitation at a location other than that of the receiver for part or all of a pulse sequence. Because the frequency "shifts" described here occur instantaneously with complete phase continuity and can excite multiple frequencies simultaneously, they offer strong advantages over methods involving actual frequency shifts. © 1992.