Energy bands and final-state effects inK0.30MoO3

An x-ray photoemission spectroscopy study of the blue molybdenum bronze ${\mathrm{K}}_{0.30}$ ${\mathrm{MoO}}_3$ shows a conduction band of Mo 4d character extending 2 eV below the Fermi level. The valence band lies between 2 and 10 eV. The Mo 3d core-electron spectrum has components at binding energies previously identified with ${\mathrm{Mo}}^{5+}$ and ${\mathrm{Mo}}^{6+}$ ions in related molybdenum oxide compounds. In this metallic system these two states are, however, of final-state origin, representing alternate screening channels and do not indicate that discrete valences are present in the initial state.