Moessbauer spectroscopy of ferromagnets in radio-frequency magnetic fields

We considered the transmission of Moessbauer radiation through a soft ferromagnetic crystal placed in the radio-frequency (rf) magnetic field, which gives rise to periodical reversals of the magnetization of the crystal. The dynamical scattering theory is presented. The energy distribution of ? rays, transmitted through a crystal FeBO3 in the rf field, is measured experimentally. The data coincide with our calculations. It is shown that the spectrum of these γ rays consists of equidistant lines spaced by twice the frequency of the applied rf field in contrast with well-known absorption spectra. This effect results from the interference of transition nuclear amplitudes.