scholarly journals Overview of nanoscale NEXAFS performed with soft X-ray microscopes

2015 ◽  
Vol 6 ◽  
pp. 595-604 ◽  
Author(s):  
Peter Guttmann ◽  
Carla Bittencourt
Keyword(s):  
Energy Storage Devices ◽  
Catalytic Systems ◽  
Full Field ◽  
X Ray ◽  
Nanoscale Structures ◽  
Advantages And Disadvantages ◽  
Nexafs Spectroscopy ◽  
Scanning Transmission ◽  
Functionalized Materials ◽  
Spectroscopy Studies

Today, in material science nanoscale structures are becoming more and more important. Not only for the further miniaturization of semiconductor devices like carbon nanotube based transistors, but also for newly developed efficient energy storage devices, gas sensors or catalytic systems nanoscale and functionalized materials have to be analysed. Therefore, analytical tools like near-edge X-ray absorption fine structure (NEXAFS) spectroscopy has to be applied on single nanostructures. Scanning transmission X-ray microscopes (STXM) as well as full-field transmission X-ray microscopes (TXM) allow the required spatial resolution to study individual nanostructures. In the soft X-ray energy range only STXM was used so far for NEXAFS studies. Due to its unique setup, the TXM operated by the Helmholtz-Zentrum Berlin (HZB) at the electron storage ring BESSY II is the first one in the soft X-ray range which can be used for NEXAFS spectroscopy studies which will be shown in this review. Here we will give an overview of the different microscopes used for NEXAFS studies and describe their advantages and disadvantages for different samples.

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.

scholarly journals Quantitative capabilities of STXM to measure spatially resolved organic volume fractions of mixed organic ∕ inorganic particles

2019 ◽  
Vol 12 (3) ◽  
pp. 1619-1633
Author(s):  
Matthew Fraund ◽  
Tim Park ◽  
Lin Yao ◽  
Daniel Bonanno ◽  
Don Q. Pham ◽  
...  
Keyword(s):  
Sodium Chloride ◽  
Ammonium Sulfate ◽  
Volume Fraction ◽  
Equal Mass ◽  
Three Solutions ◽  
Inorganic Particles ◽  
X Ray ◽  
Spatially Resolved ◽  
Nexafs Spectroscopy ◽  
Scanning Transmission

Abstract. Scanning transmission X-ray microscopy coupled with near-edge X-ray absorption and fine structure (STXM-NEXAFS) spectroscopy can be used to characterize the morphology and composition of aerosol particles. Here, two inorganic ∕ organic systems are used to validate the calculation of organic volume fraction (OVF) and determine the level of associated error by using carbon K-edge STXM data at 278, 285.4, 288.6, and 320 eV. Using the mixture of sodium chloride and sucrose as one system and ammonium sulfate and sucrose as another, three solutions were made with 10:1, 1:1, and 1:10 mass ratios (inorganic to organic). The OVFs of the organic-rich aerosols of both systems deviated from the bulk OVF by less than 1%, while the inorganic-rich aerosols deviated by approximately 1 %. Aerosols from the equal mass mixture deviated more (about 4 %) due to thick inorganic regions exceeding the linear range of Beer's law. These calculations were performed after checking the data for poor image alignment, defocusing issues, and particles too thick to be analyzed. The potential for systematic error in the OVF calculation was also tested by assuming the incorrect composition. There is a small (about 0.5 %) OVF difference if the organic is erroneously assumed to be adipic acid rather than the known organic, sucrose. A much larger difference (up to 25 %) is seen if sodium chloride is assumed instead of ammonium sulfate. These results show that the OVF calculations are fairly insensitive to the organic while being much more sensitive to the choice of inorganic.

scholarly journals Spatial distribution of starch, proteins and lipids in maize endosperm probed by scanning transmission X-ray microscopy

2019 ◽  
Author(s):  
Camille Rivard ◽  
Benedicte Bakan ◽  
Claire Boulogne ◽  
Khalil Elmorjani ◽  
Sufal Swaraj ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Maize Endosperm ◽  
Maize Breeding ◽  
X Ray ◽  
Nexafs Spectroscopy ◽  
Scanning Transmission ◽  
High Resolution Images ◽  
Ultrathin Sections ◽  
Main Components ◽  
X Ray Absorption

The main storage components of the maize endosperm are starch, proteins and lipids. Starch and proteins are heterogeneously deposited, leading to the formation of vitreous and floury regions at the periphery and at the centre of the endosperm. The vitreous/floury mass ratio is a key physical parameter of maize end-uses for the food, feed and non-food sectors, as well as for the resistance of seeds to environmental aggressions. To improve maize breeding for vitreousness, one of the main issues is to finely delineate the molecular and physicochemical mechanisms associated with the formation of endosperm texture. In this context, we use scanning transmission X-ray microscopy at the C K-edge on maize endosperm resin-embedded ultrathin sections. The combination of local near edge X-ray absorption fine structure (NEXAFS) spectroscopy and high-resolution images enable us to achieve a quantitative fine description of the spatial distribution of the main components within the endosperm.

Chemical Speciation by NEXAFS Spectromicroscopy: Insights from Molecular Modelling of Polymers

1996 ◽  
Vol 437 ◽  
Author(s):  
S. G. Urquhart ◽  
A. P. Hitchcock ◽  
E. G. Rightor ◽  
A. P. Smith ◽  
H. Ade
Keyword(s):  
Chemical Speciation ◽  
Soft Segment ◽  
Phase Segregation ◽  
Molecular Spectra ◽  
Excitation Spectra ◽  
X Ray ◽  
Nexafs Spectroscopy ◽  
Scanning Transmission ◽  
Structural Isomerization ◽  
Imaging Mode

AbstractNear Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy of polymers performed in a scanning transmission X-ray microscope (STXM) can provide chemical speciation with <0.1 gm spatial resolution in imaging mode. The core excitation spectra of molecular compounds that are structural analogues of polymers help interpret the NEXAFS spectra of polymers. The effect of nt-delocalization on polymer NEXAFS is discussed and illustrated by comparison to molecular spectra. Extended Htickel calculations are particularly useful for providing insight into the relationship between chemical structure and the molecular and polymer spectra. We report the interpretation of experimental NEXAFS spectra of polyethylene terephthalate (PET). Molecular models indicate that NEXAFS will be sensitive to structural isomerization in polyester polymers. We demonstrate the capability of NEXAFS to distinguish hard-segment and soft-segment phase segregation in polyurethanes.

scholarly journals Electron-beam induced deposition and autocatalytic decomposition of Co(CO)3NO

2014 ◽  
Vol 5 ◽  
pp. 1175-1185 ◽  
Author(s):  
Florian Vollnhals ◽  
Martin Drost ◽  
Fan Tu ◽  
Esther Carrasco ◽  
Andreas Späth ◽  
...  
Keyword(s):  
Electron Beam ◽  
Iron Pentacarbonyl ◽  
X Ray ◽  
Nexafs Spectroscopy ◽  
Novel Approach ◽  
Scanning Transmission ◽  
Layered Nanostructures ◽  
Electron Beam Induced Deposition ◽  
Autocatalytic Growth ◽  
Seed Layers

The autocatalytic growth of arbitrarily shaped nanostructures fabricated by electron beam-induced deposition (EBID) and electron beam-induced surface activation (EBISA) is studied for two precursors: iron pentacarbonyl, Fe(CO)5, and cobalt tricarbonyl nitrosyl, Co(CO)3NO. Different deposits are prepared on silicon nitride membranes and silicon wafers under ultrahigh vacuum conditions, and are studied by scanning electron microscopy (SEM) and scanning transmission X-ray microscopy (STXM), including near edge X-ray absorption fine structure (NEXAFS) spectroscopy. It has previously been shown that Fe(CO)5 decomposes autocatalytically on Fe seed layers (EBID) and on certain electron beam-activated surfaces, yielding high purity, polycrystalline Fe nanostructures. In this contribution, we investigate the growth of structures from Co(CO)3NO and compare it to results obtained from Fe(CO)5. Co(CO)3NO exhibits autocatalytic growth on Co-containing seed layers prepared by EBID using the same precursor. The growth yields granular, oxygen-, carbon- and nitrogen-containing deposits. In contrast to Fe(CO)5 no decomposition on electron beam-activated surfaces is observed. In addition, we show that the autocatalytic growth of nanostructures from Co(CO)3NO can also be initiated by an Fe seed layer, which presents a novel approach to the fabrication of layered nanostructures.

scholarly journals Quantitative capabilities of STXM to measure spatially resolved organic volume fractions of mixed organic/inorganic particle

2018 ◽  
Author(s):  
Matthew Fraund ◽  
Tim Park ◽  
Lin Yao ◽  
Daniel Bonanno ◽  
Don Q. Pham ◽  
...  
Keyword(s):  
Sodium Chloride ◽  
Ammonium Sulfate ◽  
Volume Fraction ◽  
Equal Mass ◽  
Quality Data ◽  
Three Solutions ◽  
X Ray ◽  
Spatially Resolved ◽  
Nexafs Spectroscopy ◽  
Scanning Transmission

Abstract. Scanning Transmission X-ray Microscopy coupled with Near-Edge X-ray Absorption and Fine Structure (STXM/NEXAFS) spectroscopy can be used to characterize the morphology and composition of aerosol particles. Here, two inorganic/organic systems are used to validate the determination of Organic Volume Fraction (OVF) from STXM data and to determine the level of associated error. Using the mixture of sodium chloride and sucrose as one system and ammonium sulfate and sucrose as another, three solutions each were made with 10:1, 1:1, and 1:10 mass ratios (inorganic to organic). The OVF of the organic rich aerosols of both systems deviated from the bulk OVF by less than 1 %, while the inorganic rich aerosols deviated by approximately 1 %. Aerosols from the equal mass mixture deviated more (about 4 %) due to thick inorganic regions exceeding the linear range of Beer’s Law. These calculations were performed after checking the data for image alignment, defocusing issues, and particles too thick to be analyzed. The potential for systematic error in the OVF calculation was also tested by assuming the incorrect composition. There is a small (about 0.5 %) OVF difference if adipic acid is assumed rather than sucrose, and a much larger (up to 25 %) difference if sodium chloride is assumed instead of ammonium sulfate. These results show that, with attention paid to ensuring quality data, an OVF value within 1 % of the theoretical value can be determined.

Multi-elemental scanning transmission X-ray microscopy–near edge X-ray absorption fine structure spectroscopy assessment of organo–mineral associations in soils from reduced environments

2015 ◽  
Vol 12 (1) ◽  
pp. 64 ◽  
Author(s):  
Chunmei Chen ◽  
Donald L. Sparks
Keyword(s):  
Fine Structure ◽  
X Ray ◽  
Fe Oxides ◽  
Absorption Fine ◽  
Nexafs Spectroscopy ◽  
Mineral Associations ◽  
Fundamental Process ◽  
Scanning Transmission ◽  
Mineral Components ◽  
X Ray Absorption

Environmental context Organo–mineral associations represent a fundamental process for stabilising organic carbon in soils. In this study, we employed scanning transmission X-ray microscopy–near edge X-ray absorption fine structure (STXM-NEXAFS) spectroscopy at C, Al and Si K-edges as well as Ca and Fe L-edges to conduct submicrometre-level investigations of the associations of C with mineral components in soils from reduced environments. This study provides the first insights into organo–mineral associations in reduced environments and shows progress towards examining, at the submicrometre level, compositional chemistry and associative interactions between organic matter and soil mineral components. Abstract Organo–mineral associations represent a fundamental process for stabilising organic carbon (OC) in soils. However, direct investigation of organo–mineral associations has been hampered by a lack of methods that can simultaneously characterise organic matter (OM) and soil minerals, and most investigations have focussed only on well drained soils. In this study, we employed scanning transmission X-ray microscopy–near edge X-ray absorption fine structure (STXM-NEXAFS) spectroscopy at C, Al and Si K-edges as well as Ca and Fe L-edges to conduct submicrometre-level investigations of the associations of C with mineral components in soils from reduced environments. Soils were collected from a forest footslope that is periodically poorly drained as well as a waterlogged wetland. OM was coated on mineral particles as thin films. Part of the mineral surface did not show detectable OM coverage with OC loadings of ≥1.3mg C m–2 determined for the clay fractions from these soils. C was not preferentially associated with Fe oxides in the footslope soil. A generally good C–Ca association was found in the anoxic wetland soil, which is free of Fe oxides. It was demonstrated for the first time that OM composition varied spatially at the submicrometre scale in the reduced soils free of Fe oxides. The composition of OM in the organo–mineral interface in the anoxic environments was highly complex and composed of aromatic, phenolic, aliphatic, carboxyl, carboxylamide and O-alkyl C functional groups. There was no consistent pattern for the association of certain types of organics with specific mineral components in both soils. The anoxic conditions resulted in the reduction of Fe in the aluminosilicates. This study provides the first insights into organo–mineral associations in reduced environments.

Current status of the TwinMic beamline at Elettra: a soft X-ray transmission and emission microscopy station

2016 ◽  
Vol 23 (6) ◽  
pp. 1526-1537 ◽  
Author(s):  
Alessandra Gianoncelli ◽  
George Kourousias ◽  
Lucia Merolle ◽  
Matteo Altissimo ◽  
Anna Bianco
Keyword(s):  
Materials Science ◽  
Current Status ◽  
Diffractive Imaging ◽  
Edge Structure ◽  
Full Field ◽  
X Ray ◽  
Differential Phase ◽  
Research Fields ◽  
Scanning Transmission ◽  
Phase Interference

The current status of the TwinMic beamline at Elettra synchrotron light source, that hosts the European twin X-ray microscopy station, is reported. The X-ray source, provided by a short hybrid undulator with source size and divergence intermediate between bending magnets and conventional undulators, is energy-tailored using a collimated plane-grating monochromator. The TwinMic spectromicroscopy experimental station combines scanning and full-field imaging in a single instrument, with contrast modes such as absorption, differential phase, interference and darkfield. The implementation of coherent diffractive imaging modalities and ptychography is ongoing. Typically, scanning transmission X-ray microscopy images are simultaneously collected in transmission and differential phase contrast and can be complemented by chemical and elemental analysis using across-absorption-edge imaging, X-ray absorption near-edge structure or low-energy X-ray fluorescence. The lateral resolutions depend on the particular imaging and contrast mode chosen. The TwinMic range of applications covers diverse research fields such as biology, biochemistry, medicine, pharmacology, environment, geochemistry, food, agriculture and materials science. They will be illustrated in the paper with representative results.

DIFFERENTIAL INTERFERENCE CONTRAST FOR X-RAY MICROSCOPY: FABRICATION AND CHARACTERIZATION OF TWIN ZONE PLATE OPTICS

2002 ◽  
Vol 09 (01) ◽  
pp. 243-248 ◽  
Author(s):  
ENZO DI FABRIZIO ◽  
BURKHARD KAULICH ◽  
THOMAS WILHEIN ◽  
JEAN SUSINI
Keyword(s):  
Photon Energy ◽  
Differential Interference Contrast ◽  
X Rays ◽  
Full Field ◽  
X Ray ◽  
Nomarski Differential Interference Contrast ◽  
Scanning Transmission ◽  
Imaging Performance ◽  
Dic Technique

A novel X-ray technique for converting the phase information of weakly absorbing specimen into strong image contrast similar to Nomarski differential interference contrast (DIC) is presented. DIC for X-rays is accomplished by the fabrication of a novel X-ray optic (TZP) consisting of two zone plates (ZPs) on both sides of the same substrate, laterally shifted by about one outermost zone width. The feasibility of DIC for X-rays was proven at the ID 21 X-ray microscopy beamline at the ESRF using a full-field imaging microscope and a scanning transmission X-ray microscope, which were operated at 4 keV photon energy. In both microscopes, we observe a tremendous contrast enhancement of up to a factor of 25. Though first experiments were carried out at 4 keV photon energy, this X-ray DIC technique can be adapted to any photon energy where ZPs with appropriate parameters and imaging performance can be designed and manufactured.

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