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Title: Measurement of the Full XAFS Spectrum of MgO Using Nonresonant Inelastic X-ray Scattering

Abstract

We present non-resonant inelastic x-ray scattering measurements (NRIXS) of the contribution of each initial state orbital in MgO to the dynamic structure factor. We find good agreement with previous x-ray absorption fine structure (XAFS) measurements and with previous electron energy loss spectroscopy (EELS) measurements for the corresponding edges. We also find good agreement with ab initio calculations when the interaction between the core hole and the photoelectron is treated properly. These measurements demonstrates the flexibility of a new user facility dedicated to measurement of NRIXS from core-shell electrons, the lower energy resolution inelastic x-ray scattering (LERIX) spectrometer located at sector 20 PNC-XOR of the Advanced Photon Source. The LERIX user facility provides a bulk-sensitive alternative to, and in some cases extension of, soft x-ray XAFS measurements.

Authors:
; ; ; ;  [1];  [2];  [2]
  1. (UWASH)
  2. (
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
USDOE
OSTI Identifier:
1009012
Resource Type:
Conference
Resource Relation:
Conference: 13th International Conference on X-ray Absorption Fine Structure-XAFS13;9-14 July 2006;Stanford, California, USA
Country of Publication:
United States
Language:
ENGLISH
Subject:
43 PARTICLE ACCELERATORS; ABSORPTION; ADVANCED PHOTON SOURCE; ELECTRONS; ENERGY RESOLUTION; ENERGY-LOSS SPECTROSCOPY; FINE STRUCTURE; FLEXIBILITY; SCATTERING; SPECTROMETERS; STRUCTURE FACTORS

Citation Formats

Fister, T.T., Seidler, G.T., Cross, J.O., Rehr, J.J., Soininen, J.A., APS), and Helsinki). Measurement of the Full XAFS Spectrum of MgO Using Nonresonant Inelastic X-ray Scattering. United States: N. p., 2007. Web.
Fister, T.T., Seidler, G.T., Cross, J.O., Rehr, J.J., Soininen, J.A., APS), & Helsinki). Measurement of the Full XAFS Spectrum of MgO Using Nonresonant Inelastic X-ray Scattering. United States.
Fister, T.T., Seidler, G.T., Cross, J.O., Rehr, J.J., Soininen, J.A., APS), and Helsinki). Thu . "Measurement of the Full XAFS Spectrum of MgO Using Nonresonant Inelastic X-ray Scattering". United States. doi:.
@article{osti_1009012,
title = {Measurement of the Full XAFS Spectrum of MgO Using Nonresonant Inelastic X-ray Scattering},
author = {Fister, T.T. and Seidler, G.T. and Cross, J.O. and Rehr, J.J. and Soininen, J.A. and APS) and Helsinki)},
abstractNote = {We present non-resonant inelastic x-ray scattering measurements (NRIXS) of the contribution of each initial state orbital in MgO to the dynamic structure factor. We find good agreement with previous x-ray absorption fine structure (XAFS) measurements and with previous electron energy loss spectroscopy (EELS) measurements for the corresponding edges. We also find good agreement with ab initio calculations when the interaction between the core hole and the photoelectron is treated properly. These measurements demonstrates the flexibility of a new user facility dedicated to measurement of NRIXS from core-shell electrons, the lower energy resolution inelastic x-ray scattering (LERIX) spectrometer located at sector 20 PNC-XOR of the Advanced Photon Source. The LERIX user facility provides a bulk-sensitive alternative to, and in some cases extension of, soft x-ray XAFS measurements.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Jan 18 00:00:00 EST 2007},
month = {Thu Jan 18 00:00:00 EST 2007}
}

Conference:
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  • We present non-resonant inelastic x-ray scattering measurements (NRIXS) of the contribution of each initial state orbital in MgO to the dynamic structure factor. We find good agreement with previous x-ray absorption fine structure (XAFS) measurements and with previous electron energy loss spectroscopy (EELS) measurements for the corresponding edges. We also find good agreement with ab initio calculations when the interaction between the core hole and the photoelectron is treated properly. These measurements demonstrates the flexibility of a new user facility dedicated to measurement of NRIXS from core-shell electrons, the lower energy resolution inelastic x-ray scattering (LERIX) spectrometer located at sectormore » 20 PNC-XOR of the Advanced Photon Source. The LERIX user facility provides a bulk-sensitive alternative to, and in some cases extension of, soft x-ray XAFS measurements.« less
  • We present non-resonant inelastic x-ray scattering measurements (NRIXS) of the contribution of each initial state orbital in MgO to the dynamic structure factor. We find good agreement with previous x-ray absorption fine structure (XAFS) measurements and with previous electron energy loss spectroscopy (EELS) measurements for the corresponding edges. We also find good agreement with ab initio calculations when the interaction between the core hole and the photoelectron is treated properly. These measurements demonstrates the flexibility of a new user facility dedicated to measurement of NRIXS from core-shell electrons, the lower energy resolution inelastic x-ray scattering (LERIX) spectrometer located at sectormore » 20 PNC-XOR of the Advanced Photon Source. The LERIX user facility provides a bulk-sensitive alternative to, and in some cases extension of, soft x-ray XAFS measurements.« less
  • We report measurements of the nonresonant inelastic x-ray scattering (NRIXS) from the O 1s orbitals in ice Ih, and also report calculations of the corresponding spectra for ice Ih and several other phases of water ice. We find that the intermediate-energy fine structure may be calculated well using an ab initio real-space full multiple scattering approach and that it provides a strong fingerprint of the intermediate-range order for some ice phases. Both experiment and theory find that the intermediate-range fine structure, unlike the near-edge structure, is independent of momentum transfer (q) to very high q. These results have important consequencesmore » for future NRIXS measurements of high-pressure phases of ice.« less
  • 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 threemore » 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.« less