COHERENT SUPPRESSION OF THE EPR-NUTATION SIGNAL IN QUARTZ

Bloch equations are used to derive an analytic expression for the inte gral nutation-signal decay rate in a two-level quantum system. It is f ound that when inhomogeneous line broadening is taken into account, th e temporal decay of the response is due not only to coherent suppressi on but also to additional decay whose rate depends on the ratio of the Rabi frequency to the inhomogeneous linewidth. The results are used t o explain the anomalous (Rabi-frequency-dependent) EPR-nutation decay detected in quartz in the experiments of R. Boscaino, F. M. Gelardi, a nd J. P. Corb [Phys. Rev. B 48, 7077 (1993)]. Contrary to the statemen t made by these researchers that this decay is non-Bloch, it is found that the process can be described by Bloch equations without any modif ication. (C) 1998 American Institute of Physics. [S1063-7761(98)00908- 1].