scholarly journals Ptychography Reduces Spectral Distortions Intrinsic to Conventional Zone-Plate-Based X-Ray Spectromicroscopy

2021 ◽  
pp. 1-6
Author(s):  
Matthew A. Marcus ◽  
David A. Shapiro ◽  
Young-Sang Yu
Keyword(s):  
Spatial Resolution ◽  
Image Data ◽  
Coherent Scattering ◽  
Zone Plate ◽  
X Ray ◽  
Spatially Resolved ◽  
Probe Size ◽  
Scanning Transmission ◽  
Long Tails ◽  
Conventional Microscopy

Scanning transmission X-ray microscopy is a powerful method for mapping chemical phases in nano-materials. The point spread function (PSF) of a conventional zone-plate-based microscope limits the achievable spatial resolution and also results in spatially resolved spectra that do not accurately reflect the spatial heterogeneity of the samples when the scale of the detail approaches the probe size. X-ray ptychography, a coherent-scattering-based imaging scheme that effectively removes the probe from the image data, returns accurate spectra from regions smaller than the probe size. We show through simulation how the long tails on the PSF of an x-ray optic can cause spectral distortion near a boundary between two spectrally distinct regions. The resulting apparent point spectra can appear mixed, with the species on one side of the boundary seeming to be present on the other even at a distance from the boundary equal to several times the spatial resolution. We further demonstrate the effect experimentally and show that ptychographic microscopy can return the expected spectra from a model system, whereas conventional microscopy does not.

Applications of high spatial resolution hicroanalysis to materials problems using dedicated STEM

1978 ◽  
Vol 36 (1) ◽  
pp. 418-419
Author(s):  
Ernest L. Hall ◽  
John B. Vander Sande
Keyword(s):  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Profile Analysis ◽  
Scanning Transmission Electron Microscope ◽  
Dramatic Improvement ◽  
X Ray ◽  
Transmission Electron ◽  
Probe Size ◽  
Scanning Transmission ◽  
Compositional Variations

The scanning transmission electron microscope has afforded a dramatic improvement in the spatial resolution of X-ray microanalysis of thin specimens, allowing the investigation of extremely localized compositional variations in materials systems. In this paper, the results of high resolution composition profile analysis in several materials are presented. The materials were analyzed in a 100 kV field emission STEM manufactured by VG Microscopes, Ltd., and fitted with an energy dispersive X-ray spectrometer. The specimens were held in a double-tilt graphite cartridge which allowed X-ray detection in the tilt range 0°-20° about each axis. The vacuum in the specimen chamber was ∿ 2 x 10-9 torr during analysis. Electron probe spot sizes of 5-10 Å were used, corresponding to probe currents in the range of 10-10-10-9 amps.For a given specimen composition, the spatial resolution of X-ray microanalysis in thin specimens is a function of probe size, accelerating voltage, specimen atomic number, and thickness.

Quantitative Chemical Speciation of Multi-Phase Polymers Using Zone Plate x-ray Microscopy

1998 ◽  
Vol 4 (S2) ◽  
pp. 808-809
Author(s):  
A.P. Hitchcock ◽  
S.G. Urquhart ◽  
H. Ade ◽  
E.G. Rightor ◽  
W. Lidy
Keyword(s):  
Chemical Analysis ◽  
Spatial Resolution ◽  
Phase Segregation ◽  
Zone Plate ◽  
Quantitative Chemical Analysis ◽  
X Ray ◽  
Scanning Transmission ◽  
Complex Polymers ◽  
Multi Phase ◽  
Quantitative Chemical

Phase segregation is important in determining the properties of many complex polymers, including polyurethanes. Achieving a better understanding of the links between formulation, chemical nature of segregated phases, and physical properties, has the potential to aid development of improved polymers. However, the sub-micron size of segregated features precludes detailed chemical analysis by most existing methods. Zone-plate based, scanning transmission X-ray microscopes (STXM) at NSLS and ALS provide quantitative chemical analysis (speciation) of segregated polymer phases at ∼50 nm spatial resolution. Image sequences acquire much more data with less radiation damage, than spot spectra. After alignment, they provide high quality near edge spectra, and thus quantitative analysis, at full spatial resolution.Fig. 1 shows an image and spectra acquired with the NSLS STXM of a macro-phase segregated TDI polyurethane. Spectral decomposition using model polymer spectra is used to measure the local urea, urethane and polyether content.

High spatial resolution x-ray microanalysis of interfaces

1995 ◽  
Vol 53 ◽  
pp. 284-285
Author(s):  
J. R. Michael
Keyword(s):  
Spatial Resolution ◽  
Electron Probe ◽  
Solid Angle ◽  
Collection Efficiency ◽  
Spatial Scales ◽  
Energy Dispersive Spectrometer ◽  
X Rays ◽  
X Ray ◽  
Probe Size ◽  
Brightness Field

X-ray microanalysis in the analytical electron microscope (AEM) refers to a technique by which chemical composition can be determined on spatial scales of less than 10 nm. There are many factors that influence the quality of x-ray microanalysis. The minimum probe size with sufficient current for microanalysis that can be generated determines the ultimate spatial resolution of each individual microanalysis. However, it is also necessary to collect efficiently the x-rays generated. Modern high brightness field emission gun equipped AEMs can now generate probes that are less than 1 nm in diameter with high probe currents. Improving the x-ray collection solid angle of the solid state energy dispersive spectrometer (EDS) results in more efficient collection of x-ray generated by the interaction of the electron probe with the specimen, thus reducing the minimum detectability limit. The combination of decreased interaction volume due to smaller electron probe size and the increased collection efficiency due to larger solid angle of x-ray collection should enhance our ability to study interfacial segregation.

Practical Importance of Spatial Resolution and Analytical Sensitivity in AEM X-ray Microanalysis

1990 ◽  
Vol 48 (2) ◽  
pp. 432-433
Author(s):  
J. Zhang ◽  
D.B. Williams ◽  
J.I. Goldstein
Keyword(s):  
Spatial Resolution ◽  
Practical Importance ◽  
Beam Current ◽  
Specimen Thickness ◽  
Analytical Sensitivity ◽  
Related Factors ◽  
X Ray ◽  
Probe Size ◽  
Excitation Volume ◽  
Two Parameters

Analytical sensitivity and spatial resolution are important and closely related factors in x-ray microanalysis using the AEM. Analytical sensitivity is the ability to distinguish, for a given element under given conditions, between two concentrations that are nearly equal. The analytical sensitivity is directly related to the number of x-ray counts collected and, therefore, to the probe current, specimen thickness and counting time. The spatial resolution in AEM analysis is determined by the probe size and beam broadening in the specimen. A finer probe and a thinner specimen give a higher spatial resolution. However, the resulting lower beam current and smaller X-ray excitation volume degrade analytical sensitivity. A compromise must be made between high spatial resolution and an acceptable analytical sensitivity. In this paper, we show the necessity of evaluating these two parameters in order to determine the low temperature Fe-Ni phase diagram.A Phillips EM400T AEM with an EDAX/TN2000 EDS/MCA system and a VG HB501 FEG STEM with a LINK AN10 EDS/MCA system were used.

Phase composition depth profiles using spatially resolved energy dispersive X-ray diffraction

2004 ◽  
Vol 37 (6) ◽  
pp. 967-976 ◽  
Author(s):  
Andrew C. Jupe ◽  
Stuart R. Stock ◽  
Peter L. Lee ◽  
Nikhila N. Naik ◽  
Kimberly E. Kurtis ◽  
...  
Keyword(s):  
Phase Composition ◽  
Spatial Resolution ◽  
Zinc Coating ◽  
High Energy ◽  
Sulfate Attack ◽  
Energy Dispersive ◽  
X Ray Diffraction ◽  
X Ray ◽  
Spatially Resolved ◽  
Composition Profiles

Spatially resolved energy dispersive X-ray diffraction, using high-energy synchrotron radiation (∼35–80 keV), was used nondestructively to obtain phase composition profiles along the radii of cylindrical cement paste samples to characterize the progress of the chemical changes associated with sulfate attack on the cement. Phase distributions were acquired to depths of ∼4 mm below the specimen surface with sufficient spatial resolution to discern features less than 200 µm thick. The experimental and data analysis methods employed to obtain quantitative composition profiles are described. The spatial resolution that could be achieved is illustrated using data obtained from copper cylinders with a thin zinc coating. The measurements demonstrate that this approach is useful for nondestructively visualizing the sometimes complex transformations that take place during sulfate attack on cement-based materials. These transformations can be spatially related to microstructure as seen by computed microtomography.

scholarly journals An ultrahigh-resolution soft x-ray microscope for quantitative analysis of chemically heterogeneous nanomaterials

2020 ◽  
Vol 6 (51) ◽  
pp. eabc4904
Author(s):  
David A. Shapiro ◽  
Sergey Babin ◽  
Richard S. Celestre ◽  
Weilun Chao ◽  
Raymond P. Conley ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
High Performance ◽  
Ultrahigh Resolution ◽  
High Brightness ◽  
X Ray ◽  
Correlative Analysis ◽  
Scanning Transmission ◽  
Chemical States ◽  
Scanning Mechanism ◽  
Performance Computing

The analysis of chemical states and morphology in nanomaterials is central to many areas of science. We address this need with an ultrahigh-resolution scanning transmission soft x-ray microscope. Our instrument provides multiple analysis tools in a compact assembly and can achieve few-nanometer spatial resolution and high chemical sensitivity via x-ray ptychography and conventional scanning microscopy. A novel scanning mechanism, coupled to advanced x-ray detectors, a high-brightness x-ray source, and high-performance computing for analysis provide a revolutionary step forward in terms of imaging speed and resolution. We present x-ray microscopy with 8-nm full-period spatial resolution and use this capability in conjunction with operando sample environments and cryogenic imaging, which are now routinely available. Our multimodal approach will find wide use across many fields of science and facilitate correlative analysis of materials with other types of probes.

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.

Quantification Of Segregation Levels Using Xeds In The Stem

1999 ◽  
Vol 5 (S2) ◽  
pp. 146-147
Author(s):  
V. J. Keast ◽  
D. B. Williams
Keyword(s):  
Grain Boundary ◽  
Boundary Segregation ◽  
Scanning Transmission Electron Microscope ◽  
Factor V ◽  
X Ray ◽  
Interaction Volume ◽  
Probe Size ◽  
Scanning Transmission ◽  
The Matrix ◽  
Image Position

The quantification of grain boundary segregation levels, as measured with X-ray energy dispersive spectroscopy (XEDS) in a scanning transmission electron microscope (STEM), is dependent on the size and shape of the interaction volume. The segregation level T (in atoms/nm2) is related to the intensities of the characteristic peaks in the X-ray spectrum, Is and Im, bywhere ρ is the density of the matrix in atoms/nm3, Am and As are the atomic masses of the matrix and segregant respectively and ksm is the usual k-factor. The geometric factor, V/A, is the ratio of the volume of interaction to the area of the grain boundary inside in the interaction volume. Different models have been used to describe the interaction volume and these are illustrated in Fig. 1 and the appropriate expression for V/A is given in each case. In the simplest case, beam broadening is neglected and the interaction volume can be described as a cylinder with diameter equal to the probe size, d.

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.

Sign in / Sign up

Export Citation Format

Share Document