Mössbauer Effect in Iron (III) Acetylacetonate and Chemical Consequences of K Capture in Cobalt (III) Acetylacetonate

Abstract

The resonance absorption of 14.4 keV gamma rays in Fe⁵⁷ (Mössbauer effect) has been observed in Fe(III) and Co(III) acetylacetonate, the former used as an absorber against a source of Co⁵⁷ diffused into metallic chromium, the latter as a Co⁵⁷ labeled source against an K₄Fe(CN)₆ (38%Fe⁵⁷) absorber. The Fe(III) acetylacetonate absorber spectrum shows a single broad line (Γ_½=1.83±0.09 mm sec^—1) with an isomer shift of 0.50±0.09 mm sec^—1. The Co(III) acetylacetonate source shows a complex spectrum which can be resolved into a single peak assigned to Fe(III) and a quadrupole split pair of lines assigned to Fe(II). These data are interpreted in terms of the chemical consequences following K capture in Co⁵⁷, and suggest a twofold preference for the stabilization of the higher charge state in the Co(III) acetylacetonate matrix. No evidence for ionic charge states higher than 3+ is observed, and it is assumed that these species—if formed as a consequence of the prior nuclear event—have been reduced to the observed states in times short compared to 10^—7 sec.