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Heavy Element Photophysics and Photochemistry
Gas
and Solution Phase Photophysics and Photochemistry
This effort is providing fundamental science knowledge that is essential
to generate and assess new options for addressing issues critical to the
Department of Energy (DOE) mission. Our work exploits laser-induced fluorescence
and related techniques to identify complexes of metal ions in solution,
probe the chemical consequences of photoexcitation of heavy metal fluorides,
and monitor the extent of photodestruction of complexants. We have gained
fundamental insight into the speciation of unusual solution phase complexes,
the ability of fission products to photocatalytically destroy organic
complexants, and the relative chemical and photochemical reactivity of
volatile heavy metal fluorides. In addition, our studies have the potential
to provide the basis for novel approaches for highly sensitive remote
detection of leaking uranium hexafluoride storage cylinders and cost-effectively
holding generated waste volumes to that of the removed radionuclides in
treatment of some nuclear wastes. Waste minimization, pollution prevention,
and cost avoidance are central themes of the DOE mission
 Our laser-based investigations on heavy element
compounds and complexes are generating the science knowledge base that
is essential to exploiting the unique characteristics of heavy elements.
We carry out time- and wavelength-resolved laser-induced fluorescence
(LIF) studies to speciate lanthanide and actinide metal ion complexes
in solution and probe the chemical consequences of photoexcitation of
volatile heavy metal fluorides, such as technetium hexafluoride. Our basic
research investigations are generating a predictive understanding of the
consequences of electronic excitation of heavy elements and provide a
basis to assess new options for achieving waste minimization, pollution
prevention, and cost avoidance in handling, treating, and storing nuclear
waste.
(Click on the image to see an animated depiction of some of our research.)
Recent
Program Accomplishments
Future
Research
To date, our research on the photophysics and speciation of excited uranyl
fluorides in aqueous hydrofluoric (HF) solutions has been conducted at
or near ambient temperature. Although no work on the temperature dependence
of the photophysics or speciation of excited uranyl fluorides in aqueous
solutions has been reported, it is known from past studies by others that
most uranyl complexes exhibit temperature dependent luminescence lifetimes
and emission spectra. We will determine the temperature dependence of
the photophysics and speciation of uranyl fluorides in aqueous HF solutions.
Our investigation of these important complexes will cover a range of temperature
limited by solidification at low temperature and rapid sample cell corrosion
or excessive pressure at high temperature. In addition we will examine
the influence of other metal ions, such as those resulting from corrosion
of steel, on uranyl luminescence in such solutions.
We expect to continue our work on functionalized silica gel as a means
of generating nanophase, metal-bearing regions within fused silica and
as a material capable of sorbing radionuclides from solution and, upon
thermal densification, serving as the final waste form for disposal of
such material. This work will center on characterization of thermally
processed (densified), metal-loaded Diphosil using a broad range of techniques
such as diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS)
to determine hydroxyl content, conventional and optically detected nuclear
magnetic resonance to characterize the local environment of metal ions,
and analytical electron microscopy to determine the presence of crystalline
nanophase regions and the chemical composition of such regions if they
are present.
Contact
For more information, contact
Dr. James V. Beitz.
Return to Heavy Element Photophysics and Photochemistry
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Glassblowing
Interfacial
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Materials Growth Facility
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Atomic Physics
Nanophotonics
Heavy
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f-Electron
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Actinide
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