Excitation and Detection of Coherence between Forbidden Levels in Three-Level Spin System by Multi-Step Processes

Abstract

The coherent superposition of the states between which magnetic dipole transition is forbidden has been excited and detected by means of a multi-step application of resonant rf pulses in a three-level NMR system. The experiment was carried out on ²⁷Al nuclei in Al₂O₃ where the quantization axes of the quadrupole and the magnetic coupling were parallel. Free decay and echo signals associated with the coherence were observed, and transfer of coherence between nonresonant pairs of levels was studied in detail.