XES, XPS and NEXAFS studies of the electronic structure of cubic MoO1.9 and H1.63MoO3 thick films

X-ray emission spectroscopy (XES), X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) methods were used to study the electronic structure of cubic MoO1.9 and H1.63MoO3 thick films. For comparison, the orthorhombic form of molybdenum trioxide, MoO3, was also studied. XP valence-band and Mo 3d and O 1s core-level spectra, O Kalpha emission bands and NEXAFS O 1s spectra were measured. Half-widths of both the XP valence-bands and O Kalpha emission bands decreases in the sequence cubic H1.63MoO3 --> orthorhombic MoO3 --> cubic MoO1.9. The XPS and NEXAFS data reveal that the charge states of oxygen atoms do not change in the above sequence of compounds. The formation of an additional near-Fermi sub-band is characteristic for the XP valence-band spectra of cubic MoO1.9 and H1.63MoO3. The XES measurements indicate that the energy positions of maxima and of the centers of gravity of the O Kalpha bands remain constant within accuracy of the experiment for all the compounds studied. (C) 2003 Elsevier B.V. All rights reserved.