NEXAFS multiple scattering calculations of KO2

Since many years the oxidation of alkali metals has being attracted much in terest due to the catalytic properties of metal promoters and the simple el ectronic structure of alkali atoms. The alkali-oxides phase diagram indicat es that the interaction of oxygen with alkali metals can lead to the format ion of different atomic O2- ions and molecular O-2(-) and O-2(2-) ions. Pot assium superoxide has been prepared in situ and high resolution O k-edge ab sorption NEXAFS spectra have been measured at the VUV beam-line at ELETTRA facility. The experimental data have been analyzed by multiple scattering a pproach deriving many geometrical and electronic details. In particular, we have found that the growth material structure is of the KO2 type with an O -O distance of about 1.35 Angstrom and that the transition involving single pi molecular empty state of the superoxide O-2(-) anion has a fine structu re. Multiple Scattering self consistent calculation indicates that the bond between oxygen anion and K atom is totally ionic and that the fine structu re is essentially due to solid state effects.