Mössbauer diffraction. III. Emission of Mössbauerγrays from crystals. B. Dynamical solutions

Abstract

The dynamical solutions for the emission of Mössbauer $\gamma$ rays from crystals are examined. It is found that enhanced-intensity "anomalous-emission" Kossel lines occur in the early development of an active source as a consequence of the fact that the electronic scattering absorption of the lattice is predominantly $E1\mathrm{}$, while most Mössbauer transitions correspond to the emission of higher-order-multipole waves. The sensitivity of the Mössbauer scattering to the magnetic field and electric-field-gradient tensor at the nucleus gives rise to "magnetic Kossel cones" which uniquely exhibit the structure of the internal fields when it differs from the chemical structure of the crystal. Faraday effects are also important in describing the polarization state of the emitted $\gamma$ quanta. The phase of the x-ray structure factor of (molecular) crystals can be determined by Kossel-cone analysis. Applications of the theory to the problems of obtaining enhanced highly collimated Mössbauer-$\gamma$-ray sources, and the problems of magnetic and chemical structure determinations by Kossel-cone analysis are presented.