On the validity of a Fe-57 hyperfine magnetic field distribution measured by a monochromatic, circularly polarized Mossbauer source

It is demonstrated that when in a standard Mossbauer spectroscopy experimen t two different hyperfine magnetic field distributions describe experimenta l data equally well, measurements by means of a monochromatic circularly po larized source lead to the correct choice of the solution. The problem of t he asymmetry of the spectrum in the case of a polarized source and pure mag netic interaction is discussed and constraints for the line intensities are given.