Generating Novel Spin Echoes Using the Internal Structure of Strong Pi-Pulses

Conventionally, strong pulses used to control coherent evolution are approximated as instantaneous, perfect rotations. However, recent experiments have shown a surprising departure from the conventional theory in standard multipulse NMR experiments using strong pi-pulses. Using our understanding of the role that the finite time duration of any real pulse plays in these effects, we design and experimentally demonstrate new classes of spin echoes.