Limits on the Lifetime of Nonequilibrium Fe3+ Ions in Some Ionic Solids from the Mössbauer Effect

The lifetime of higher valence states produced by Auger effect can be obtained from the Mossbauer effect in the case of some favorable isotopes. It is shown that valence states higher than Fe2+ which are produced following the electron capture decay of divalent 57Co in ZnF2 have lifetimes less than 10−8 sec. A similar limit is obtained for the lifetimes of higher charge states of iron produced by divalent cobalt diffused into NaF with the aid of charge‐compensating sodium vacancies. Trivalent iron has lifetimes greater than 3×10−8 sec in NaF, if charge compensation is accomplished by oxygen. The lifetime in hydrated ferrous ammonium sulfate is 5×10−8 sec. The short lifetimes even of Fe3+ in some divalent lattices indicate that the lifetimes of higher valences will generally be too short to be observed with the present technique. It also suggests that valence states which do not occur in stable compounds will generally have short lifetimes and be difficult to detect.