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Title: | X-ray spectroscopic investigations of fluids in the hydrothermal diamond anvil cell: The hydration structure of aqueous La3+ up to 300 ∞C and 1600 bars |
Authors: | Anderson, J. Jayanetti, J. K. D. S. Mayanovic, Robert A. Bassett, William A. Chou, I-Ming |
Issue Date: | 2002 |
Citation: | American Mineralogist, Volume 87, pages 262–268, 2002 |
Abstract: | The first direct measurements are reported for the structure of the hydrated La3+ ion in an aqueous solution (containing 0.007 m La) over a range of temperatures from 25 to 300 ∞C and pressures up to 1600 bars. The radial distribution of atoms around the La3+ ion was measured using the X-ray absorption fine structure (XAFS) technique. La L3-edge spectra were collected in the fluorescence mode from nitrate solutions in a modified hydrothermal diamond anvil cell using the PNC-CAT Xray microprobe at the Advanced Photon Source, Argonne National Laboratory. Analysis of the XAFS spectra collected at all temperatures indicates that each La3+ ion has a hydration number of nine and that the solvating waters surround the ion in a tricapped trigonal prismatic arrangement. As temperature is increased from 25 to 300 ∞C, the bond distance between the equatorial-plane O atoms and the La3+ ion increases from 2.59 ± 0.02 to 2.79 ± 0.04 Å, whereas the bond distance between La3+ and the O atoms at the ends of the prism decrease to 2.48 ± 0.03 Å. This study also demonstrates the unique capability of the modified hydrothermal diamond anvil cell for in situ low energy X-ray spectroscopic analysis of elements in dilute aqueous solutions at elevated temperatures and pressures. |
URI: | http://archive.cmb.ac.lk:8080/xmlui/handle/70130/225 |
Appears in Collections: | Department of Physics |
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