Valence Determination by Electron Energy Loss Spectroscopy of the Multi-Valence Metal Chromium
Abstract
Chromium is a redox active 3d transition metal with a wide range of valences (-2 to +6) that control the geochemistry and toxicity of the element. A variety of Cr-bearing minerals are found in meteorites of all petrographic classes lunar basalts, Martian rocks, and the Earth, recording valuable information concerning geochemical conditions of mineralization. Natural weathering of Cr- bearing minerals and fallout of volcanic ash release Cr into the terrestrial environment. Furthermore, Cr compounds are widely used in numerous industrial processes which can discharge toxic Cr complexes in soils/sediments and surface/ground waters, as well as the atmosphere in the form of aerosols. Therefore, techniques that measure Cr valence are important biogeochemical tools. Until now, all established methods to determine Cr valence were bulk techniques with many specific to a single, or at best, only a few oxidation state(s). We report electron energy loss spectroscopy (EELS) techniques that, unlike other methods, can determine Cr valence at high-spatial resolution (nm-scale) over a wide valence range, Cr(O) to Cr(VI).
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 2005
- Accession Number
- ADA480622
Entities
People
- Brenda J. Little
- T. L. Daulton
Organizations
- United States Naval Research Laboratory