Scientific Program

Research Techniques

X-Ray Microprobe and Spectroscopy

X-ray fluorescence (XRF) microprobe allows non-destructive determination of elemental composition of samples, especially for heavy elements (Z>16).  By scanning a sample in a micron-scale X-ray beam, images of elemental distribution can be made.  X-ray absorption fine structure (XAFS) probes the local atomic and chemical environment of a selected atomic species by scanning the X-ray energy across the binding energy of a core electron of a selected element.  X-ray absorption near-edge spectra (XANES) is sensitive to the valence state of the selected element. The extended XAFS (EXAFS) modulations in the absorption well above the X-ray absorption edge threshold give quantitative information about coordination species, number and distance of the selected element.

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Interface, Surface Studies & Powder Diffraction

Surface and interface diffraction techniques are used to obtain fundamental knowledge on the structures of surfaces, how these surfaces are modified during hydroxylation and dehydroxylation processes, sorption reactions that occur on these surfaces and the role of biota in controlling the stabilization of toxins and contaminants on these surfaces.

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High Pressure / High Temperature Diamond Anvil Cell

The main goal of the diamond anvil cell program is to address geochemical and geophysical problems across the entire pressure- temperature range of the Earth and other terrestrial planets.

High pressure research using diamond anvil cells (DACs) provide access to the sample volume for x-rays as low as 15 keV, allowing powder and single crystal diffraction measurements to be made. These measurements will help to unravel the chemical and physical secrets of the deep Earth including phase transitions of mantle minerals and core alloys and dynamics of core formation.

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High Pressure / High Temperature Large Volume Press

The Large Volume Press (LVP) facilities hosts the following devices:

• 1000 ton multi-function press at 13-ID-D
• 250 ton multi-function press at 13-BM-D
• 230 ton Paris-Edinburgh press at 16-BM-B of HPCAT

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Tomography

Tomographic imaging techniques are used to study the internal microstructures of complex materials. At GSECARS, computed microtomography is used to study a variety of geological samples. These range from the internal structures of precious samples like fossils, the distribution and location of inclusions in diamonds, the porosity and density of weathered rocks, studies of granular flow, and the transport of fluids such as water and oils in porous media.

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