Temperature-dependent after-effects of the cobalt-57–iron-57 electron-capture reaction in Cd3[57Co(CN)6]2,12H2O

Abstract

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)₆^3– and one to ⁵⁷Fe(CN)₅^2–; 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)₅^2– 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)₆^3–.