Observations and interpretation of x-ray absorption edges in iron compounds and proteins.

X-ray absorption spectra near the Kalpha edge have been measured in various iron group compounds using the intense synchrotron radiation at the Stanford Synchrotron Research Project. In the cubic compounds KMF3 where M = Mn+2, Fe+2, Co+2, Ni+2, and Zn+2, well resolved lines were observed and assigned to the 1s leads to 3d, 1s leads to 4s, and 1s leads to 4p transitions. The observed energies agreed rather well with the spectroscopic energy levels of the Z + 1 ion and the intensities are shown to agree with those expected on the basis of one electron transitions of the form Z 1s2dn(L,S) leads to (Z + 1)1s2dnn'l'(L",S).