X-Ray Microprobe, Spectroscopy & Microtomography

Overview - XAFS / XANES

X-ray absorption fine structure (XAFS) probes the local atomic and chemical environment of a selected atomic species. By analyzing the modulations in the absorption coefficient at energies just above the x-ray absorption edge threshold, XAFS measurements give quantitative information about coordination species, number and distance. The x-ray absorption near-edge spectra (XANES) are also sensitive to the valence state of the probe atom.

Principal Techniques

  • Near edge XANES
  • Extended x-ray absorption (EXAFS)
  • Grazing incidence XAFS
  • Quick - XAFS

XAFS Experiments

  • Speciation of metals in soils, sediments and organisms
  • Grazing incidence studies of cations and anions on surfaces (model systems and natural crystallites)
  • Time-resolved studies of reactions on surfaces and interfaces
  • High temperature studies (trace elements in melts)
  • Oxidation states of planetary materials

Overview - X-ray Microprobe

Electron image of an interplanetary dust particle (~10 microns) collected in the Earth's stratosphere. The x-ray microprobe instrumentation is designed to be capable of fluorescence analysis (XRF), XAFS and microtomography. The undulator microprobe is designed for ultrahigh spatial resolution, high sensitivity and pencil-beam microtomography.

 

Microprobe Characteristics

  • Microfocused undulator radiation (KB Mirrors)
  • High-resolution fluorescence detection
  • Micro-XAFS

Microprobe Experiments

  • Compositions of buried components (fluid inclusions)
  • Trace element partitioning in natural and experimental samples
  • Compositional mapping (diffusion, zonation)
  • Sector zoning in minerals
  • Compositions of mocroparticles (soils, micrometeorites, aerosols)
  • Oxidation state mapping (microXAFS)

► GSECARS Staff - X-ray Spectroscopy and  Microprobe


► Links for Additional Information

XAFS.org
XAFS.org is a community site for x-ray absorption fine-structure (XAFS) and related spectroscopies.

EnviroSync
EnviroSync is an organization of environmental science users of synchrotron radiation facilities.

IUCr Commission on XAFS
This organization promotes the development and acceptance of XAFS standards, works ot increase the interaction among XAFS reseaqrchers and promotes the improvement of the XAFS experimental facilities at synchrotron sources.

Lunar and Planetary Institute
The Lunar and Planetary Institute is a research institute that provides support services to NASA and the planetary science community