Chemical shifts and fine structure of the cobalt K -absorption edge

We have measured the chemical shifts of the x‐ray K ‐absorption edge of cobalt in the compounds ${\mathrm{CoF}}_2,{\mathrm{CoO,\; Co}}_2{\mathrm{O}}_3,\mathrm{Co}({\mathrm{CH}}_3\mathrm{COO}{)}_2\text{· 4}{\mathrm{H}}_2{\mathrm{O,\; CoSO}}_4\text{· 7}{\mathrm{H}}_2{\mathrm{O,\; CoC}}_2{\mathrm{O}}_4\text{· 2}{\mathrm{H}}_2{\mathrm{O,\; CoCl}}_2\text{· 6}{\mathrm{H}}_2{\mathrm{O,\; CoBr}}_2,{\mathrm{CoS,\; CoCO}}_3$ , and Co₃(PO₄)₂ 8H₂O. The chemical shifts have been found to vary linearly with the product i m², where i is the ionicity and m the valence. We have also measured the fine structure observed on the high energy side of the edge in the metal and in the first six compounds. The positions of maxima and minima have been compared with theoretical predictions. The first absorption maximum in the metal has been interpreted as a plasma absorption. The bond lengths have been estimated from the fine structure.