Effect of interaction of electromagnetic fields with a resonant medium in epr when the saturating field is small compared with the local field

We propose a system of Bloch equations, modified to take into account the presence of a dipole-dipole reservoir (DDR), for the case when the saturating magnetic field is small compared with the local field. We take into account the transverse and longitudinal magnetizations in the equation for the DDR, in contrast to our previous papers in which we took into account only the longitudinal magnetization. Using the system obtained, we solve the problem of the interaction of three fields, where one is the saturating field, the second is the probe field, and the third is a combination field that is the result of the interaction of the first two fields in a resonant medium. We have studied the imaginary and real parts of the susceptibility of the system at the probe field frequency, both when the interacting waves have different frequencies and when they have matching frequencies (the degenerate case). We have compared the results with those we obtained previously. For the degenerate case, we consider the frequency dependence of the parametric coupling coefficient of the waves. We show that weak waves can be enhanced as they pass through a layer of a resonant absorbing medium. © 2006 Springer Science+Business Media, Inc.