Core-exciton absorption in the FKabsorption spectra of 3dtransition-metal fluorides

Near-edge structure in the F K absorption spectra of 3d transition-metal fluorides, ${\mathrm{MnF}}_2$, ${\mathrm{FeF}}_2$, ${\mathrm{CoF}}_2$, ${\mathrm{NiF}}_2$, ${\mathrm{CuF}}_2$, and ${\mathrm{ZnF}}_2$, are measured. The shoulder structures or weak peaks located at the absorption threshold are observed. The origin of these peaks is attributed to the core-exciton absorption. This core-exciton absorption is accompanied by the transition from the 1s orbitals of fluorides to the 3d orbitals of the metal ion which hybridized with the anion 2p orbitals. Chemical shifts of the first peak are clearly observed and discussed in terms of the ionization potentials of the metal ions. It is found that the F K absorption spectra of the 3d transition-metal fluorides are quite similar to the Cl K absorption spectra of the 3d transition-metal chlorides.