Analytical description of the effect of adiabatic pulses on IS, I2S, and I3S spin systems.

An analytical description of the evolution of magnetization in InS spin systems (1 </= n </= 3) during the course of an adiabatic pulse applied on spin S is provided. Calculations show that multiple-quantum terms are created during the pulse and that the rate at which in-phase and antiphase I-spin magnetization components interchange during spin-echo-based pulse sequences is decreased relative to the case where a hard inversion pulse is substituted for the adiabatic pulse. This has important consequences for purging schemes making use of such frequency-swept pulses. Simulations demonstrate that the evolution of in-phase I magnetization is essentially independent of n. Copyright 1998 Academic Press.