Transient nutations decay: The effect of field-modified dipolar interaction

The anomalous behavior of transient nutations is experimentally investigated in a set of two-level (S=1/2) spin systems differing only in spin concentration. Our results show that the non-Bloch power dependence of the decay rate of transient nutations is a concentration-dependent effect, which is more and more pronounced in more and mon concentrated samples. The experimental results are interpreted in the framework of the recent theory by Shakhmuratov et al. [Phys. Rev. Lett. 79, 2963 (1997)] and support the hypothesis that the anomalous decay of transient nutations in solids originates from radiation-induced changes of the dipolar field, rather than from residual fluctuations of the nominally coherent field. [S1050-2947(99)03905-0].