Electronics structures of Rb, Cs and some of their metallic oxides studied by photoelectron spectroscopy

Photoemission measurements with He and Ne resonance lines and Al Kα radiation are reported on bulk samples of the alkali metals Rb, Cs, their suboxides Cs7O, Cs11O3 and (Cs11O3)Rb7. For comparison, the Hel spectrum of the “normal” oxide Cs2O is added. The occurrence of ionic clusters in a metallic matrix is typical for the suboxides. Binding energies, Auger transitions, and electron concentrations are discussed. The spectra of the suboxides show a narrow non-bonding oxygen 2p band at 2.7 eV. Different binding energies are found for Cs atoms in the clusters and for the atoms in the metallic regions of (Cs11O3)Cs10. The compound Cs11O3 consists of ionic [Cs11O3]5− clusters, which are bound by 5 free electrons in accordance with the chemical bond model.