The Mössbauer Effect and its Significance in Chemistry

Abstract

Abstract Resonance fluorescence of recoil‐free γ‐rays from atomic nuclei depends on the state of the chemical bonding of the atoms. The latter influences the position of the energy level of the atomic nuclei, so that the energy required for excitation of resonance fluorescence is somewhat smaller or greater than the energy of the γ‐quanta emitted by the radiation source. In order to obtain resonance fluorescence, therefore, the radiation source and absorber have to be kept moving relative to each other. If the intensity of the resonance fluorescence is plotted against this relative velocity, Mössbauer spectra are obtained. The positions of the lines in these spectra make it possible to draw conclusions about the nature of the atom's bonds. The efficiency of this method is demonstrated by illustration with numerous iron compounds. It was shown, for instance, that the iron atoms in “insoluble Prussian Blue” have well‐defined oxidation levels. “Turnbull's Blue” shows the identical spectrum. A structure could be ascribed to tri‐iron dodecacarbonyl that also explains the diamagnetism of the compound.