A THEORETICAL AND EXPERIMENTAL INVESTIGATION OF MULTIPLET SPLITTING FOR TRANSITION METAL AND URANIUM SPECTRA GENERATED BY XPS AND XANES
EMSL Project ID
3058a
Abstract
Abstract updated 10/15/2005This work involves developing strict ab initio many body models for the XPS of open shell metals, including the 3d transition metals and uranium. We have recently extended our work to include modeling the L-edge of transition metals and the O K-edge for XANES. The objectives are to use the theory to help elucidate information about oxidation state and bonding environment that is contained in the fine structures of the XPS and L-edge spectra of these elements.
We have made advances in the interpretation of XPS fine structures in transition metals. For Mn, we have identified new many-body effects that correctly give the energetic separation of the exchange-split doublet in the 3s XPS(Bagus et al. 2004a). For Cr, we have established the roles and importance of intra-atomic and inter-atomic effects for the 2p and 3p XPS of Cr2O3. (Ilton et al., 2003 and Bagus et al., 2004b) Further, we have shown that the XPS reflects the chemical interactions between the metals and the ligands; this analysis of the chemical bonding has become possible because of the unique theoretical capabilities that we have developed (Bagus and Ilton, in review a). These initial studies, while of interest in themselves, demonstrate that we have theoretical tools to study complex structures of TMs and of actinides. Indeed, in support of the experimental efforts to characterize and to establish the stability of pentavalent U, we have determined the first ab initio predictions of the atomic contributions to the 4f XPS of U(IV) and U(V)(Ilton and Bagus, 2005). We have also explored the potential implications of Rydberg orbitals on the O K-edge XANES spectru for H2O (Bagus and Ilton , in review b).
In summary, we have made major advances in the development of programs to accurately calculate the XPS intensities for many-body relativistic wavefunctions; these programs give us unique capabilities to study XPS spectra where spin-orbit splitting is important. Future applications will establish the systematics of one-body and many-body contributions to the 2p XPS (and L-edge XANES)of embedded transition metal cations as functions of oxidation state and environment.
Ilton E.S. and Bagus P.S. (2005) Many body effects in the 4f XPS of the U5+ and U4+ free ions. Phys. Rev. B. 71, 195121.
Bagus P.S., Broer R. and Ilton E.S. (2004a) A new near degeneracy effect for photoemission in transition metals. Chem. Phys. Letters 394, 150.
Bagus P.S., Ilton E.S., and Rustad J.R. (2004b) Ligand field effects for the 3p photoelectron spectra of Cr2O3. Phys. Rev. B 69, 205112.
Ilton E.S, DeJong W., and Bagus P.S. (2003) Intra-atomic many-body effects for the p-shell photoelectron spectra of the Cr3+ ions. Phys. Rev. B. 68, 125106.
Bagus P.S. and Ilton E.S. (In review a)The effect of covalency on the p-shell photoemission of transition metal: MnO. Submitted to Phys. Rev. B.
Bagus P.S. and Ilton E.S. (In review b) A Definitive Analysis of the Rydberg and Valence Anti-bonding Character of the O K-edge of H2O. Submitted to Chem. Phys. Lett.
Project Details
Project type
Exploratory Research
Start Date
2005-11-25
End Date
2007-03-22
Status
Closed
Released Data Link
Team
Principal Investigator