On the influence of coherent inelastic resonance scattering on the Mössbauer absorption spectra

Abstract

It is shown that an unusual angular distribution in coherent inelastic Mössbauer scattering (MCIS) manifests itself in Mössbauer absorbtion spectra (MAS). This is due to the fact that MCIS connected with the phonon assisted processes is concentrated in the direction of the incident Mössbauer beam propagation. The manifestation of MCIS in MAS in the case of MAS hyperfine splitting is analyzed. The effect reveals itself in the ratios of hyperfine line intensities in MAS due to the fact that the MCIS cross-section is different for different MAS hyperfine lines. In particular, for the case of thick nuclear resonance absorber the dips in MAS are different for the different hyperfine lines. (Usually it is assumed that for thick absorber the amplitudes of the dips are the same for all lines.) The general expressions for the intensity ratios for different MAS hyperfine lines which take into account MCIS are given in the case of hyperfine magnetic splitting. Estimates show that the corrections to the conventionally assumed ratios of line intensities in MAS are usually not large but quite measurable. However in the favorable cases (isotopes with low values of internal conversion coefficients) they can be as large as ten percent.