Ratio-contrast imaging of dual-energy absorption for element mapping with a scanning transmission X-ray microscope

Abstract

The detection of chemical mapping with a spatial resolution of 30 nm has been achieved with a scanning transmission X-ray microscope at the Shanghai Synchrotron Radiation Facility. For each specimen, two absorption images were scanned separately with energies E(1) and E(2): E(1) was focused on the absorption edge of the chosen element and E(2) was focused below the edge. A K-edge division method is proposed and applied to obtain the element mapping. Compared with the frequently used K-edge subtraction method, this ratio-contrast method is shown to be more accurate and sensitive in identifying the elements of interest, where the definition of the contrast threshold is simple and clear in physics. Several examples are presented to illustrate the effectiveness of the method.

Chromium immobilization by extra- and intraradical fungal structures of arbuscular mycorrhizal symbioses

“…A dual-energy ratio contrast analysis was conducted to investigate the spatial distribution of different Cr species in the chosen regions of the samples [36]. The detailed STXM analytic methods are described in the Supplementary information.…”

A Unique Feature of Iron Loss via Close Adhesion of Helicobacter pylori to Host Erythrocytes

“…It is suitable for analysis of multiple elements. It has already been used in the initial analysis of many biological samples, including botanical samples [11], [27], [28]. To date, there has been no report of any analysis of human red blood cells and H. pylori at a synchrotron radiation facility.…”

“…Previously, we used the new technique to study the imaging of biological samples and element distribution [10], [11]. In the current study, we examined the interactions between H. pylori and human erythrocytes from ABO blood groups and to examine the distribution of iron.…”

Differential expression of extracellular thiol groups of moderately thermophilic Sulfobacillus thermosulfidooxidans and extremely thermophilic Acidianus manzaensis grown on S0 and Fe2+

“…The STXM images of the samples were scanned in two dimensions with a step of 30 nm and a dwell time of 20 ms at E1 and E2 under ultrahigh vacuum (<10 −5 Torr). The distribution of iron species was obtained by digital division of two absorption-contrast images at dual photon energies of E1 and E2 using IDL 7.06 (Exelis Visual Information Solutions, Inc. Boulder, CO, USA) software (Xue et al 2010;Zhang et al 2010).…”