  We performed a systematic study of soft X-ray absorption spectroscopy in
various manganese oxides and fluorides. Both Mn L-edges and ligand (O and F)
K-edges are presented and compared with each other. Despite the distinct
crystal structure and covalent/ionic nature in different systems, the Mn-L
spectra fingerprint the Mn valence and spin states through spectral lineshape
and energy position consistently and evidently. The clear O- and F- K pre-edge
features in our high resolution spectra enable a quantitative definition of the
molecular orbital diagram with different Mn valence. In addition, while the
binding energy difference of the O-1s core electrons leads to a small shift of
the O-K leading edges between trivalent and quadrivalent manganese oxides, a
significant edge shift, with an order of magnitude larger in energy, was found
between divalent and trivalent compounds, which is attributed to the spin
exchange stabilization of half- filled 3d system. This shift is much enhanced
in the ionic fluoride system. This work provides the spectroscopic foundation
for further studies of complicated Mn compounds.

Materials Science