Resonant Gamma-Ray Absorption in Potassium Ferrate

The Mössbauer spectrum in a potassium ferrate absorber has been determined at 78° and 298°K using a source of Co57 in stainless steel. A single resonance line is observed with a full width at half-maximum of 0.43 mm sec—1. This linewidth is known to arise mainly in the stainless-steel source, which indicates that the quadrupole splitting of the resonance peak is less than 1 Mc sec—1. The isomer shift is —0.69 mm sec—1 at 78°K and —0.79 mm sec—1 at 298°K. This shift is smaller than that predicted for a 3d2 electron configuration, presumably because the 3d electron density is augmented by d3s hybridization in the tetrahedral ferrate ion.