Dresden 2003 – wissenschaftliches Programm

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O: Oberflächenphysik

O 40: Elektronische Struktur V

O 40.6: Vortrag

Freitag, 28. März 2003, 12:30–12:45, M\"UL/ELCH

Ab initio DFT cluster studies of NEXAFS spectra of V₂O₅(010) and V₂O₃(0001) surfaces — •Christine Kolczewski and Klaus Hermann — Fritz-Haber-Institut der Max-Planck Gesellschaft, Faradayweg 4-6, 14195 Berlin

At the (010) surface of the structurally complex vanadium pentoxide, V₂O₅, there are differently coordinated oxygen centers (1-, 2-, 3-fold) which can participate as active sites in specific surface reactions. In the present work we use ab initio density functional theory (DFT) together with cluster models to calculate the core level spectra of the three different oxygen sites of the V₂O₅(010) surface. We obtain characteristic differences for the spectra. Excitation energies and intensities are determined by details of the local V-O binding but also by electronic relaxation. The angular dependency of the core level spectra is computed as well. A comparison of our theoretical spectra with experimental NEXAFS data is rather satisfactory.

The V₂O₃(0001) surface allows three ideal terminations, two metal and one oxygen topped, while two additional terminations, vanadyl and oxygen stabilized metal, have been proposed on chemical grounds. Here we use the same methods as described above to evaluate the NEXAFS spectra. By comparison with experimental angle resolved NEXAFS spectra of the V₂O₃(0001) surface we might be able to assign the experimental surface termination.

This work is supported by SFB 546 No-dqTransitionmetalaggregatesNo-dq.