No abstract available

No abstract available

No abstract available

No abstract available

No abstract available

No abstract available

No abstract available

[en] A quadrupole Fe⁵⁷ polarimeter consisting of single crystals of LiNbO₃:Co⁵⁷ as source (polarizer) and of FeCO₃ (siderite) as absorber (analyzer) is described). The quadrupole interactions of the two materials are nearly equal in magnitude but opposite in sign and in addition the asymmetry parameter eta equal approximately 0

[en] ⁵⁷Fe Moessbauer absorption profiles were calculated supposting distributions of all hyperfine parameters: hyperfine magnetic fields, isomer shifts, and electric field gradients. The effect of mixed hyperfine interactions was taken into account in all orders of perturbation theory. The shapes of the spectra were systematically studied for varying average values and widths of the hyperfine magnetic field distributions (HMFD). From the simulated spectra, the shapes of the HMFD were reconstructed using standard techniques of Moessbauer spectra processing which neglect the effects of random isomer shifts and electric field gradients. It has been shown that the reconstructed shapes of the HMFD differ qualitatively from the original single-peaked distributions and exhibit a double-peaked structure similar to the distributions found in many experiments on amorphous alloys with low iron content. A brief reveiw of various mechanisms responsible for either apparent or real double-peaked structure of HMFD has been given. (orig.)

[en] A study of Fe³⁺ environments in alkali silicate glasses has been performed. The Moessbauer parameters indicate Fe in octahedral as well as in tetrahedral surroundings. The broad linewidth of the Moessbauer subspectra indicates a distribution of the hyperfine parameters due to local distortions. Using a distribution fitting program information was obtained about the distortions of octahedral and tetrahedral Fe ion surroundings from the distribution of the electric field gradient. (Auth.)