Mortar samples from the Abbey of Saint John at Müstair: a combined spatially resolved X-ray fluorescence and X-ray absorption (XANES) study

2015 ◽  
Vol 30 (3) ◽  
pp. 702-706 ◽  
Author(s):  
Josef Hormes ◽  
Qunfeng Xiao ◽  
Yongfeng Hu ◽  
Christine Bläuer ◽  
Anja Diekamp ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
X Ray ◽  
Spatially Resolved ◽  
Saint John ◽  
X Ray Absorption

Three mortar samples from the Abbey of Saint John, in the Swiss village of Mustair have been investigated using synchrotron radiation based techniques (XRF and XANES).

scholarly journals Sample Environment for Operando Hard X-ray Tomography—An Enabling Technology for Multimodal Characterization in Heterogeneous Catalysis

Catalysts ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 459
Author(s):  
Johannes Becher ◽  
Sebastian Weber ◽  
Dario Ferreira Sanchez ◽  
Dmitry E. Doronkin ◽  
Jan Garrevoet ◽  
...  
Keyword(s):  
Heterogeneous Catalysis ◽  
Synchrotron Radiation ◽  
Contrast Imaging ◽  
Co2 Methanation ◽  
Full Field ◽  
X Ray ◽  
Spatially Resolved ◽  
Oxidation Of Methane ◽  
Unique Source ◽  
Sample Environment

Structure–activity relations in heterogeneous catalysis can be revealed through in situ and operando measurements of catalysts in their active state. While hard X-ray tomography is an ideal method for non-invasive, multimodal 3D structural characterization on the micron to nm scale, performing tomography under controlled gas and temperature conditions is challenging. Here, we present a flexible sample environment for operando hard X-ray tomography at synchrotron radiation sources. The setup features are discussed, with demonstrations of operando powder X-ray diffraction tomography (XRD-CT) and energy-dispersive tomographic X-ray absorption spectroscopy (ED-XAS-CT). Catalysts for CO2 methanation and partial oxidation of methane are shown as case studies. The setup can be adapted for different hard X-ray microscopy, spectroscopy, or scattering synchrotron radiation beamlines, is compatible with absorption, diffraction, fluorescence, and phase-contrast imaging, and can operate with scanning focused beam or full-field acquisition mode. We present an accessible methodology for operando hard X-ray tomography studies, which offer a unique source of 3D spatially resolved characterization data unavailable to contemporary methods.

Machine Learning Powered by Principal Component Descriptors as the Key for Sorted Structural Fit of XANES

2021 ◽  
Author(s):  
Andrea Martini ◽  
Alexander A. Guda ◽  
Sergey A. Guda ◽  
Aram L. Bugaev ◽  
Olga V. Safonova ◽  
...  
Keyword(s):  
Machine Learning ◽  
Structural Analysis ◽  
Synchrotron Radiation ◽  
Free Electron Laser ◽  
Principal Component ◽  
Analytical Tool ◽  
X Ray ◽  
Radiation Sources ◽  
X Ray Absorption

Modern synchrotron radiation sources and free electron laser made X-ray absorption spectroscopy (XAS) an analytical tool for the structural analysis of materials under in situ or operando conditions. Fourier approach...

X-Ray Absorption Spectra of Uranium by Synchrotron Radiation

1981 ◽  
Vol 20 (8) ◽  
pp. L612-L614 ◽  
Author(s):  
Hirohiko Adachi ◽  
Kazumi Fujima ◽  
Kazuo Taniguchi ◽  
Chie Miyake ◽  
Shosuke Imoto
Keyword(s):  
Synchrotron Radiation ◽  
Absorption Spectra ◽  
X Ray ◽  
X Ray Absorption

scholarly journals Spatially Resolved Characterization of Biogenic Manganese Oxide Production within a Bacterial Biofilm

2005 ◽  
Vol 71 (3) ◽  
pp. 1300-1310 ◽  
Author(s):  
Brandy Toner ◽  
Sirine Fakra ◽  
Mario Villalobos ◽  
Tony Warwick ◽  
Garrison Sposito
Keyword(s):  
Careful Consideration ◽  
Bacterial Biofilm ◽  
Bacterial Cells ◽  
X Ray ◽  
Spatially Resolved ◽  
Nexafs Spectroscopy ◽  
Promising Tool ◽  
Scanning Transmission ◽  
X Ray Absorption

ABSTRACT Pseudomonas putida strain MnB1, a biofilm-forming bacterial culture, was used as a model for the study of bacterial Mn oxidation in freshwater and soil environments. The oxidation of aqueous Mn+2 [Mn+2 (aq)] by P. putida was characterized by spatially and temporally resolving the oxidation state of Mn in the presence of a bacterial biofilm, using scanning transmission X-ray microscopy (STXM) combined with near-edge X-ray absorption fine structure (NEXAFS) spectroscopy at the Mn L2,3 absorption edges. Subsamples were collected from growth flasks containing 0.1 and 1 mM total Mn at 16, 24, 36, and 48 h after inoculation. Immediately after collection, the unprocessed hydrated subsamples were imaged at a 40-nm resolution. Manganese NEXAFS spectra were extracted from X-ray energy sequences of STXM images (stacks) and fit with linear combinations of well-characterized reference spectra to obtain quantitative relative abundances of Mn(II), Mn(III), and Mn(IV). Careful consideration was given to uncertainty in the normalization of the reference spectra, choice of reference compounds, and chemical changes due to radiation damage. The STXM results confirm that Mn+2 (aq) was removed from solution by P. putida and was concentrated as Mn(III) and Mn(IV) immediately adjacent to the bacterial cells. The Mn precipitates were completely enveloped by bacterial biofilm material. The distribution of Mn oxidation states was spatially heterogeneous within and between the clusters of bacterial cells. Scanning transmission X-ray microscopy is a promising tool for advancing the study of hydrated interfaces between minerals and bacteria, particularly in cases where the structure of bacterial biofilms needs to be maintained.

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