Interpretation of Oxygen Near-Edge Absorption Spectrum of CsO2 by Means of Multiple- Scattering Analysis

The codeposition of O2 and Cs on different substrates has been studied by means of near-edge X-my absorption fine-structure (NEXAFS) experiments. A multiple-scattering analysis shows that the material formed has a tetragonal CsO2 structure with an O-O distance between 1.35 and 140 angstrom. About 19 shells (52 atoms) are necessary to reproduce the oxygen K-edge absorption spectrum of this superoxide, in contrast with recent results by Ruckman et al. (Phys. Rev. Lett., 67 (1991) 2533) which are based on a free-ion calculation.