SREL Reprint #2389

Micro-XAS studies with sorbed plutonium on tuff

Martine C. Duff1, Matthew Newville2, Douglas B. Hunter1, Paul M. Bertsch1, Stephen R. Sutton2,
Ines R. Triay3, David T. Vaniman3, Peter Eng2, and Mark L. Rivers2

1The University of Georgia, Drawer E, Savannah River Ecology Laboratory, Aiken, SC 29802, USA
2Dept. Geophysical Sciences and Center for the Advanced Radiation Sources (GSE-CARS),
University of Chicago, Chicago, IL 60637, USA
3Los Alamos National Laboratory, Los Alamos, NM 87545, USA

Abstract: The bonding environment of sorbed species at rock-water interfaces provides information on their mobility in natural systems. To investigate Pu sorption at a natural surface on a microscopic scale, we studied the bonding environment of sorbed Pu on zeolitic tuff with micro-XAS techniques. Using a focused 4 by 7 µM2 beam, XAS spectra were taken at Mn-smectite regions where high levels of sorbed Pu were found. The Pu did not sorb to Fe-rich regions. XANES spectra show the presence of Pu(VI), based on edge energy. Preliminary analyses of the micro-EXAFS spectra indicate the absence of a first shell splitting of axial and equatorial Pu-O bonds—an environment unlike what is observed for most hexavalent actinides.

Keywords: micro-EXAFS; micro-XANES; micro-XRF; sorption; plutonium.

SREL Reprint #2389

Duff, M.C., M. Newville, D.B. Hunter, P.M. Bertsch, S.R. Sutton, I.R. Triay, D.T. Vaniman, P. Eng, and M.L. Rivers. 1999. Micro-XAS studies with sorbed plutonium on tuff. Journal of Synchrotron Radiation 6:350-352.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).