The electronic structure of stoichiometric and substoichiometric titanium nitride (TiN) and zirconium nitride (ZrN) have been studied with ultraviolet and x-ray photoelectron spectroscopy. The valence-band spectrum of stoichiometric TiN is compared with calculations of the density of states. Peak positions and widths agree quite well, whereas photon-energy-dependent intensity variations do not seem to follow the trends expected from the atomic photoionization cross sections. The more tightly bound metal core lines are shifted to higher binding energies by about 1.4 eV in the compounds compared to those in the pure metals. In contrast to earlier investigations of similar compounds, no difference in the binding energies of the metal core lines could be detected as a function of stoichiometry. Discrepancies were found between the experimental results and a coherent-potential-approximation calculation of the effects of substoichiometry in TiN. Neither the strong increase of states at the Fermi level nor the predicted shift of the valence-band peak could be detected. An extra peak around 2-eV binding energy was found in the substoichiometric TiN and ZrN samples and assigned to an occupied defect state. For $\mathrm{Ti}{\mathrm{N}}_{1\ensuremath{-}x}$ the peak intensity is comparable to that of the peak at the Fermi level, whereas for $\mathrm{Zr}{\mathrm{N}}_{1\ensuremath{-}x}$ this peak is broader and less pronounced.

Photoemission study of the electronic structure of stoichiometric and substoichiometric TiN and ZrN

Vibrational properties of carbon nitride films by Raman spectroscopy

The valence band structures (VBS) of eight transition metals (Fe, Co, Ni, Cu, Pd, Ag, Pt, Au) were investigated by photoelectron spectroscopy (PES) using He I, He II, and monochromatized Al Kα excitation. The influence of final states, photoionization cross-section, and adsorption of residual gas molecules in an ultrahigh vacuum environment are discussed in terms of their impact on the VBS. We find that VBSs recorded with monochromatized Al Kα radiation are most closely comparable to the ground state density of states (DOS) derived from quantum mechanics calculations. We use the Al Kα-excited PES measurements to correct the energy scale of the calculated ground-state DOS to approximate the “true” ground-state d-band structure. Finally, we use this data to test the d-band center model commonly used to predict the electronic-property/catalytic-activity relationship of metals. We find that a simple continuous dependence of activity on d-band center position is not supported by our results (both experimentall...

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Using Photoelectron Spectroscopy and Quantum Mechanics to Determine d-Band Energies of Metals for Catalytic Applications

Electron spectroscopy. X-ray and electron excitation

XPS-spectra of iron metal with special emphasis on the valence band region are reported. The valence band spectrum is in qualitative agreement with that obtained from UPS measurements with 21 eV photons. A comparison with theoretical density of states curves shows reasonable agreement, if the matrix element modulation, lifetime broadening, the inelastic scattering of electrons, the production of electron hole pairs by the photohole, and the instrumental resolution are taken into account. The production of electron hole pairs by a photohole in the valence band seems to be smaller than by a photohole in a core level. This is not unexpected in view of the delocalized nature of these valence electrons.

V.G. Aleshin

Papers

Electron structure and chemical binding in the titanium and vanadium compounds

The effect of transition probability on the shape of X-ray photoelectron spectra of diamond and silicon

Transition probability effect on the shape of electron energy distribution in X-ray electron spectra of copper, silver and palladium

X-Ray photoelectron spectra of III-IV and II-VI crystals and the bond-orbital model