I study actinide interactions with environmental matrices. Basic
scientific knowledge of the interactions controlling the transport and
migration of actinides is required. Especially important are interfacial
reactions at the boundary between aqueous radionuclide solutions and
minerals, organic and biological substances to accurately model and
predict the ultimate fate of the radionuclides stored in repositories.
My research interests include the use of the following techniques:
• Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy, a
spectroscopy method which uses X-rays to probe the nearest neighbors of
a specific element. Using this technique one can probe bonding around a
particular element regardless of the phase in which the sample is in.
This allows the experimenter to gain knowledge about bond distances,
oxidation states, and coordination numbers of non-crystalline materials
around a central atom, something which is extremely difficult, if not
impossible to do with other methods.
• High Energy X-ray Scattering (HEXS), a relatively new method of
structural determination which is well suited for actinide research. The
scattering of X-rays is proportional to the number of electrons that a
scattering element contains which means that actinides (Z > 90) scatter
X-rays much better than lighter elements. HEXS also allows the
experimenter to probe non-crystalline material in solution.
• Computational modeling, an often used method of confirming and guiding
experimental work as well as calculating possible structures from data
taken from EXAFS and HEXS. Computational modeling in actinide research
is still quite young and has not been as fully applied to actinides as
it has been to the lighter elements of the periodic table. Much of the
difficulty in applying computational modeling to the actinides is due to
the relativistic effects of the actinide electrons which greatly change
the chemistry of these elements.
Both EXAFS and HEXS are spectroscopic methods which probe the molecular
structure of actinide elements, an approach which is greatly needed to
better understand the individual molecular interaction of actinides at
environmental interfaces and in solutions.
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