Atomic multiplets at theL2,3edge of 3dtransition metals and the ligand K edge in x-ray absorption spectroscopy of ionic systems

Abstract

Experimental X-ray absorption spectra at the fluorine K and transition metal $L$${}_{2,3}$ absorption edges of the $M$F${}_{2}$ ($M=\text{Cr}$-Ni) family are presented. Ligand field calculations in D${}_{4h}$ symmetry show very good agreement with the transition metal $L$${}_{2,3}$ XAS spectra. To successfully explain nominal Cr${}^{2+}$ $L$${}_{2,3}$ XAS spectrum in CrF${}_{2}$, the inclusion of Cr${}^{+}$ and Cr${}^{3+}$ was needed implying the presence of a disproportionation reaction. The multiplet calculations were then modified to remove the structure of the 2$p$ hole in the calculated $M$ $2p\ensuremath{\rightarrow}3d$ absorption spectra. These results for the $3{d}^{n+1}$ states are in one to one correspondence with the leading edge structures found at the fluorine K edge. A direct comparison with the metal $L$${}_{2,3}$ edges also indicates that there is evidence of the metal multiplet at the fluorine K pre-edge structures.