Experimental and Theoretical Comparison of the O K-Edge Nonresonant Inelastic X-ray Scattering and X-ray Absorption Spectra of NaReO[subscript 4]

Journal Article · Tue Dec 07 04:00:00 EST 2010 · J. Am. Chem. Soc.

DOI:https://doi.org/10.1021/ja1040978· OSTI ID:1002910

Bradley, Joseph A; Yang, Ping; Batista, Enrique R; Boland, Kevin S; Burns, Carol J; Clark, David L; Conradson, Steven D; Kozimor, Stosh A; Martin, Richard L; Seidler, Gerald T; Scott, Brian L; Shuh, David K; Tyliszczak, Tolek; Wilkerson, Marianne P; Wolfsberg, Laura E ^[1]

---

1. PNNL

Accurate X-ray absorption spectra (XAS) of first row atoms, e.g., O, are notoriously difficult to obtain due to the extreme sensitivity of the measurement to surface contamination, self-absorption, and saturation affects. Herein, we describe a comprehensive approach for determining reliable O K-edge XAS data for ReO{sub 4}{sup 1-} and provide methodology for obtaining trustworthy and quantitative data on nonconducting molecular systems, even in the presence of surface contamination. This involves comparing spectra measured by nonresonant inelastic X-ray scattering (NRIXS), a bulk-sensitive technique that is not prone to X-ray self-absorption and provides exact peak intensities, with XAS spectra obtained by three different detection modes, namely total electron yield (TEY), fluorescence yield (FY), and scanning transmission X-ray microscopy (STXM). For ReO{sub 4}{sup 1-}, TEY measurements were heavily influenced by surface contamination, while the FY and STXM data agree well with the bulk NRIXS analysis. These spectra all showed two intense pre-edge features indicative of the covalent interaction between the Re 5d and O 2p orbitals. Density functional theory calculations were used to assign these two peaks as O 1s excitations to the e and t{sub 2} molecular orbitals that result from Re 5d and O 2p covalent mixing in T{sub d} symmetry. Electronic structure calculations were used to determine the amount of O 2p character (%) in these molecular orbitals. Time dependent-density functional theory (TD-DFT) was also used to calculate the energies and intensities of the pre-edge transitions. Overall, under these experimental conditions, this analysis suggests that NRIXS, STXM, and FY operate cooperatively, providing a sound basis for validation of bulk-like excitation spectra and, in combination with electronic structure calculations, suggest that NaReO{sub 4} may serve as a well-defined O K-edge energy and intensity standard for future O K-edge XAS studies.

• Research Organization: Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, IL (US)
• Sponsoring Organization: USDOE
• OSTI ID: 1002910
• Journal Information: J. Am. Chem. Soc., Journal Name: J. Am. Chem. Soc. Journal Issue: (39) ; 10, 2010 Vol. 132; ISSN JACSAT; ISSN 0002-7863
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ABSORPTION SPECTRA
ATOMS
DETECTION
ELECTRONIC STRUCTURE
ELECTRONS
EXCITATION
FLUORESCENCE
FUNCTIONALS
MICROSCOPY
SATURATION
SCATTERING
SELF-ABSORPTION
SENSITIVITY
SPECTRA
SURFACE CONTAMINATION
SYMMETRY
VALIDATION