Temperature-dependent After-Effects of the Cobalt-57-Iron-57 Electron-Capture Reaction in Cd3[57Co(CN)6]2,12H2O

The Mössbauer emission spectrum of Cd3[57Co(CN)6]2,12H2O was measured at temperatures between 78 and 323 K. Above 200 K the spectra can be resolved into two doublets; one is ascribed to 57Fe(CN)63– and one to 57Fe(CN)52–; it is suggested that the pentacyanide is formed by a Coulomb explosion following an Auger process associated with the 57Co(EC)57Fe-decay. Below 200 K a third species is detected; it may be Fe2+ formed by cyanide linkage isomerism. Measurements of the total intensity of the spectrum and the relative intensities of the individual doublets as a function of temperature permit in principle a determination of the f-factors for the species formed. It is estimated that the 57Fe(CN)52– has a formal Debye temperature of 170 K; at room temperature it is detected with a probability of only 50% of that of the 57Fe(CN)63–.