The molecular KLL Auger spectra of fluorine have been measured from HF
, LiF, NaF, and KF. The change in the ionic character of the chemical
bond is clearly seen as narrowing of the KL(2,3)L(2,3) structure on go
ing from HF to KF. Theoretical calculations using the multiconfigurati
onal CASSCF method are also found to predict well these changes. Compa
rison with the calculated KLL Auger spectrum of the fluorine ion F- ve
rifies the conclusions.