THE ELECTRONIC-STRUCTURE OF CAMNOX WITH LESS-THAN-OR-EQUAL-TO-X-LESS-THAN-OR-EQUAL-TO-3.00

We studied the electronic structure of CaMnOx with 2.66 less than or e qual to x less than or equal to 3.00 by means of soft X-ray absorption spectroscopy (XAS). The Mn 2p XAS spectra present changes in the shap e of the multiplets and chemical shifts. The chemical shifts indicate a decrease of the Mn 3d count as the oxygen content increases. The Mn 2p XAS spectra are calculated projecting the atomic multiplet on the a ppropriate crystal field. The O 1s XAS spectra show an increase in the absorption intensity just above the bottom of the conduction band. Th is effect indicates an increase of unoccupied O 2p states for larger o xygen contents. The O 1s XAS spectra are calculated using cluster mode l calculations which include charge transfer processes. We conclude th at the doped holes in the CaMnOx system contain a mixture of metal and ligand character. (C) 1997 Elsevier Science Ltd.