Calibration of theFe57Isomer Shift

Abstract

The $s$-electron density at the iron nucleus in KFe${\mathrm{F}}_{3}$ is calculated as a function of the Fe-F distance, using the Heitler-London model and the Hartree-Fock ionic wave functions. By comparing the calculated "overlap-induced" $s$-electron density with the hydrostatic pressure isomer shift measurements in KFe${\mathrm{F}}_{3}$, the relative change of the ${\mathrm{Fe}}^{57}$ nuclear radius is found to be -5.2\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}4}$, which is to be compared with the value -1.8\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}3}$ derived previously by Walker et al.