Optical and Chemical Characterization of Uranium Dioxide (UO ₂ ) and Uraninite Mineral: Calculation of the Fundamental Optical Constants

Journal Article · Thu Aug 09 00:00:00 EDT 2018 · Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory

DOI:https://doi.org/10.1021/acs.jpca.8b05943· OSTI ID:1471225

DeVetter, Brent M.  ^[1]; Myers, Tanya L. ^[1]; Cannon, Bret D. ^[1]; Scharko, Nicole K. ^[1]; Kelly-Gorham, Molly Rose K. ^[1]; Corbey, Jordan F.  ^[1]; Schemer-Kohrn, Alan L. ^[1]; Resch, C. Tom ^[1]; Reilly, Dallas D. ^[1]; Johnson, Timothy J.  ^[1]

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1. Pacific Northwest National Laboratory, 902 Battelle Blvd., Richland, Washington 99352, United States

Quantitative infrared single-angle reflectance spectroscopic measurements using a calibrated Fourier transform infrared spectrometer were performed on synthetic uranium dioxide (UO2), high-purity crystalline uraninite, and massive uraninite mineral. The massive uraninite mineral was found to contain not only UO2 but also large amounts of calcite and silicates. From the experimentally measured reflectance spectra across two spectral domains (the far- and mid-infrared) the fundamental optical constants n and k were calculated using the Kramers-Kronig transformation for each species. We discuss both the derived n and k results for these species as well as the careful sample preparation needed in order to mount, polish, and measure such samples through a wide spectral range using modern instrumentation and data processing techniques. Our results for the optical constants n and k of synthetic UO2 differ significantly from previously published literature values. This is attributed to both improved spectroscopic resolution but also to a better understanding of potential surface oxidation effects on the measured reflectance values, and hence the calculated optical constants.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Office of Defense Nuclear Nonproliferation
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1471225
• Report Number(s): PNNL-SA-135514
• Journal Information: Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory, Vol. 122, Issue 35; ISSN 1089-5639
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English