Soft x-ray spectroscopy and imaging of interfacial chemistry in environmental specimens

Abstract

Interfaces between minerals and water, and minerals and microbes, are chemically complex and have traditionally been considered beyond the capabilities of surface science techniques, except for model systems under controlled laboratory conditions. We report on some advances in soft xray spectroscopy and imaging that make it possible to extract meaningful chemical information about interfaces of specimens that have complex histories, involving environmental exposure. These measurements utilize x-ray absorption spectroscopy, in combination with spatial resolution, in a technique called x-ray spectro-microscopy. Examples are drawn from attempts at Mn and Fe speciation of biologically produced minerals, bio-corrosion deposits, and clays.

Feasibility tests of transmission x-ray photoelectron emission microscopy of wet samples

“…Other non-UHV spectromicroscopy techniques, including the full-field and scanning approaches, have already demonstrated their performances on wet samples. [8][9][10] To our knowledge, the present data represent the first evidence of the feasibility of wet sample X-PEEM in UHV.…”

MANGANESE STAINING OF ARCHAEOLOGICAL GLASS: THE CHARACTERIZATION OF Mn-RICH INCLUSIONS IN LEACHED LAYERS AND A HYPOTHESIS OF ITS FORMATION

“…This might be the result of the presence of Mn(II) and Mn(IV) in close proximity. Between the Mn(IV) inclusions, insoluble Mn(II) hydroxides or carbonates might be present as well (Tonner et al . 1999).…”

The Organic-Mineral Interface in Biominerals

“…Another article analyzed the changes in elemental concentrations between adhering and suspended bacteria using hard X-ray fl uorescence spectromicroscopy (Kemner et al 2004). Other studies used XANES or STXM-XANES spectromicroscopy, to analyze the oxidation states of biomineral products (Grush et al 1996;Tonner et al 1999;Toner et al 2005). The latter studies, being all in the soft-X-ray region have the potential of analyzing both the mineral and the organic components of biominerals.…”