Line Shape of Mössbauer Hyperfine Spectra

A general theory of the line shape of Mössbauer hyperfine spectra is developed within the framework of a new operator space formulation. In the present paper, this theory is applied to hyperfine spectra in the paramagnetic region. The phenomenological Wickman equations are derived from a microscopic quantum mechanical starting point. Explicit expressions for the relaxation terms are obtained, which make possible their discussion and evaluation and a comparison of Mössbauer results with the results of other measurements, especially those of the longitudinal susceptibility χ ‖ . It is suggested that the discrepancies so far reported between Mössbauer and paramagnetic relaxation experiments are caused by the use of concentrated samples in the latter case.