Overview of nanoscale NEXAFS performed with soft X-ray microscopes

Guttmann,; Bittencourt, Luiz F.

doi:10.1515/nano.bjneah.6.61

Cited by 5 publications

(4 citation statements)

References 37 publications

(40 reference statements)

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“…General X-Ray Microscopy Modes. Current state-of-art X-ray microscopy includes full-view transmission X-ray microscopy and scanning transmission X-ray microscopy [97,98]. The full-view transmission X-ray microscopy is similar in principle to that of optical bright-field microscopy.…”

Section: X-ray Microscopymentioning

confidence: 99%

Recent Development in X-Ray Imaging Technology: Future and Challenges

Chen

et al. 2021

Research

111

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X-ray imaging is a low-cost, powerful technology that has been extensively used in medical diagnosis and industrial nondestructive inspection. The ability of X-rays to penetrate through the body presents great advances for noninvasive imaging of its internal structure. In particular, the technological importance of X-ray imaging has led to the rapid development of high-performance X-ray detectors and the associated imaging applications. Here, we present an overview of the recent development of X-ray imaging-related technologies since the discovery of X-rays in the 1890s and discuss the fundamental mechanism of diverse X-ray imaging instruments, as well as their advantages and disadvantages on X-ray imaging performance. We also highlight various applications of advanced X-ray imaging in a diversity of fields. We further discuss future research directions and challenges in developing advanced next-generation materials that are crucial to the fabrication of flexible, low-dose, high-resolution X-ray imaging detectors.

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Section: X-ray Microscopymentioning

confidence: 99%

Recent Development in X-Ray Imaging Technology: Future and Challenges

Chen

et al. 2021

Research

111

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“…Some areas on mineral particles displayed the absence of C(K) signal, high absorption (probably significantly saturated), and by negative peaks at 284 and 290 eV (Figures 3b and 5b). The latter are a consequence of rapid changes in 1st and 2nd order light at these energies, due to carbon contamination of the beamline optics (Guttmann & Bittencourt, 2015; Hanhan et al, 2009). On the thinner areas of the particles, the NEXAFS signature of C could be recorded (Figures 3a,c and 4).…”

Section: Resultsmentioning

confidence: 99%

Nanoscale chemical mapping of exometabolites at fungal–mineral interfaces

et al. 2022

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Mineral‐associated organic matter is an integral part of soil carbon pool. Biological processes contribute to the formation of such organo‐mineral complexes when soil microbes, and in particular soil fungi, deposit a suite of extracellular metabolic compounds and their necromass on the mineral surfaces. While studied in bulk, micro‐ to nanoscale fungal–mineral interactions remain elusive. Of particular interest are the mutual effects at the interface between the fungal exometabolites and proximal mineral particles. In this work, we have grown saprotrophic and symbiotic fungi in contact with two soil minerals with contrasting properties: quartz and goethite, on top of X‐ray transparent silicon nitride membrane windows and analyzed fungal hyphae by synchrotron‐based scanning transmission X‐ray microscopy in combination with near edge X‐ray fine structure spectroscopy at C(K) and Fe(L) absorption edges. In the resultant chemical maps, we were able to visualize and differentiate organic compounds constituting the fungal cells, their extracellular metabolites, and the exometabolites adsorbing on the minerals. We found that the composition of the exometabolites differed between the fungal functional guilds, particularly, in their sugar to protein ratio and potassium concentration. In samples with quartz and goethite, we observed adsorption of the exometabolic compounds on the mineral surfaces with variations in their chemical composition around the particles. Although we did not observe clear alteration in the exometabolite chemistry upon mineral encounters, we show that fungal–mineral interaction result in reduction of Fe(III) in goethite. This process has been demonstrated for bulk systems, but, to our knowledge, this is the first observation on a single hypha scale offering insight into its underlying biological mechanisms. This demonstrates the link between processes initiated at the single‐cell level to macroscale phenomena. Thus, spatially resolved chemical characterization of the microbial–mineral interfaces is crucial for an increased understanding of overall carbon cycling in soil.

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“…Thirteen different rock varnish samples from different environments and locations worldwide, containing diverse structures and compositions, were investigated (for details, see Macholdt et al, 2015Macholdt et al, , 2017a. The soft X-rays in the STXM-NEXAFS analysis generate comparatively low radiation damage, provide a high penetration depth (Guttmann and Bittencourt, 2015), and allow investigating comparatively rich spectroscopic features for a variety of elements (Hitchcock, 2015). Among the accessible elements are C, N, and O -and, thus, the composition of organic matter inside the varnish -as well as the L-shell absorption edges of high-Z elements, such as the varnish-relevant elements Mn and Fe (Cosmidis and Benzerara, 2014).…”

Section: Introductionmentioning

confidence: 99%

Artifacts from manganese reduction in rock samples prepared by focused ion beam (FIB) slicing for X-ray microspectroscopy

Macholdt

Förster

Müller

et al. 2019

Geosci. Instrum. Method. Data Syst.

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Abstract. The spatial distribution of transition metal valence states is of broad interest in the microanalysis of geological and environmental samples. An example is rock varnish, a natural manganese (Mn)-rich rock coating, whose genesis mechanism remains a subject of scientific debate. We conducted scanning transmission X-ray microscopy with near-edge X-ray absorption fine-structure spectroscopy (STXM-NEXAFS) measurements of the abundance and spatial distribution of different Mn oxidation states within the nano- to micrometer thick varnish crusts. Such microanalytical measurements of thin and hard rock crusts require sample preparation with minimal contamination risk. Focused ion beam (FIB) slicing was used to obtain ∼100–1000 nm thin wedge-shaped slices of the samples for STXM, using standard parameters. However, while this preparation is suitable for investigating element distributions and structures in rock samples, we observed artifactual modifications of the Mn oxidation states at the surfaces of the FIB slices. Our results suggest that the preparation causes a reduction of Mn4+ to Mn2+. We draw attention to this issue, since FIB slicing, scanning electron microscopy (SEM) imaging, and other preparation and visualization techniques operating in the kilo-electron-volt range are well-established in geosciences, but researchers are often unaware of the potential for the reduction of Mn and possibly other elements in the samples.

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Overview of nanoscale NEXAFS performed with soft X-ray microscopes

Cited by 5 publications

References 37 publications

Recent Development in X-Ray Imaging Technology: Future and Challenges

Recent Development in X-Ray Imaging Technology: Future and Challenges

Nanoscale chemical mapping of exometabolites at fungal–mineral interfaces

Artifacts from manganese reduction in rock samples prepared by focused ion beam (FIB) slicing for X-ray microspectroscopy

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