| AVS 60th International Symposium and Exhibition | |
| Actinides and Rare Earths Focus Topic | Tuesday Sessions |
| Session AC+AS+SS-TuM |
| Session: | The Surface Science of Actinides and Rare Earths |
| Presenter: | P.S. Bagus, University of North Texas |
| Authors: | P.S. Bagus, University of North Texas E.S. Ilton, Pacific Northwest National Laboratory C.J. Nelin, Consultant |
| Correspondent: | Click to Email |
The covalent character of ionic metal compounds, in particular oxides, may lead to substantial departures from nominal oxidation states. [1, 2] Since this covalent character changes the effective charge of the cation, it contributes to the chemical and physical properties of these compounds. We present a new and novel method of determining the degree of the covalent mixing by projection of cation and ligand orbitals [2, 3] on the total wavefunctions for clusters used to model the electronic structure of these compounds. An important advantage of this method is that it provides estimates of the uncertainties of the assignments of effective charges to the cations and anions. Such estimates of the uncertainty directly reflect the overlap of cation and anion orbitals and, hence, their potential for chemical bonding; estimates of the uncertainty of charge assignments are not generally available. There is evidence that the properties of the spectra from X-Ray photoemission spectroscopy, XPS, [2] and X-Ray Adsorption spectroscopy, XAS, [4] reflect the extent of the covalent mixing of the cation and anion orbitals. We will consider how the covalent character changes between the initial and final state configurations in these spectroscopies, which arise from the screening of the core-hole, affect the interpretation of the core-level spectroscopies.
1. P. S. Bagus and E. S. Ilton, Phys. Rev. B 73, 155110 (2006).
2. P. S. Bagus, E. S. Ilton, and C. J. Nelin, Surf. Sci. Rep. (in press).
3. C. J. Nelin, P. S. Bagus, and M. R. Philpott, J. Chem. Phys. 87, 2170 (1987).
4. S. G. Minasian, J. M. Keith, E. R. Batista, K. S. Boland, D. L. Clark, S. D. Conradson, S. A. Kozimor, R. L. Martin, D. E. Schwarz, D. K. Shuh, G. L. Wagner, M. P. Wilkerson, L. E. Wolfsberg, and P. Yang, J. Am. Chem. Soc. 134, 5586 (2012).