Аннотации:
The multiple scattering theory is developed for y-quanta, passing through a crystal of arbitrary thickness in the if field. It is found that the y-photon, being absorbed and then emitted by the nuclear exciton can exchange with the rf field only by couples of the rf photons. As a result, the corresponding FS spectra consist of equidistant lines spaced by twice the frequency Q. of the rf field in contrast to the absorption spectra with satellites spaced by Q.. In addition, the Mossbauer absorption and FS spectra are measured for the weak ferromagnet FeBO3 in the rf field, which are well reproduced by our calculations.