Symmetric phase-alternating composite pulses.

A. J. Shaka and A. Pines

Department of Chemistry, University of California, Berkeley, California 94720, USA.

Materials and Molecular Research Division, Lawrence Berkeley Laboratory, Berkeley, California 94720, USA.

We derive sequences of new composite pulses that can provide constant rotations of arbitrary flip angle in the presence of large resonance offset effects. These symmetric sequences use only 180° phase shifts, and have the same symmetry properties as a single radiofrequency pulse. For two-level systems, these composite pulses behave like ideal single rf pulses, making them of potential use in a wide variety of experimental situations.