scholarly journals Coincidence Detection of EELS and EDX Spectral Events in the Electron Microscope

2021 ◽  
Vol 11 (19) ◽  
pp. 9058
Author(s):  
Daen Jannis ◽  
Knut Müller-Caspary ◽  
Armand Béché ◽  
Jo Verbeeck
Keyword(s):  
Electron Microscope ◽  
Reference Sample ◽  
Time Correlation ◽  
Coincidence Detection ◽  
Time Of Arrival ◽  
X Rays ◽  
Silicon Drift Detector ◽  
Recording Time ◽  
X Ray ◽  
Digital Pulse

Recent advances in the development of electron and X-ray detectors have opened up the possibility to detect single events from which its time of arrival can be determined with nanosecond resolution. This allows observing time correlations between electrons and X-rays in the transmission electron microscope. In this work, a novel setup is described which measures individual events using a silicon drift detector and digital pulse processor for the X-rays and a Timepix3 detector for the electrons. This setup enables recording time correlation between both event streams while at the same time preserving the complete conventional electron energy loss (EELS) and energy dispersive X-ray (EDX) signal. We show that the added coincidence information improves the sensitivity for detecting trace elements in a matrix as compared to conventional EELS and EDX. Furthermore, the method allows the determination of the collection efficiencies without the use of a reference sample and can subtract the background signal for EELS and EDX without any prior knowledge of the background shape and without pre-edge fitting region. We discuss limitations in time resolution arising due to specificities of the silicon drift detector and discuss ways to further improve this aspect.

X-ray micro tomography in the scanning electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 106-107 ◽  
Author(s):  
W. Brünger
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Target Surface ◽  
The Body ◽  
X Rays ◽  
Cross Sectional ◽  
X Ray ◽  
Micro Tomography ◽  
Scanning Electron

Reconstructive tomography is a new technique in diagnostic radiology for imaging cross-sectional planes of the human body /1/. A collimated beam of X-rays is scanned through a thin slice of the body and the transmitted intensity is recorded by a detector giving a linear shadow graph or projection (see fig. 1). Many of these projections at different angles are used to reconstruct the body-layer, usually with the aid of a computer. The picture element size of present tomographic scanners is approximately 1.1 mm2.Micro tomography can be realized using the very fine X-ray source generated by the focused electron beam of a scanning electron microscope (see fig. 2). The translation of the X-ray source is done by a line scan of the electron beam on a polished target surface /2/. Projections at different angles are produced by rotating the object.During the registration of a single scan the electron beam is deflected in one direction only, while both deflections are operating in the display tube.

PHAX-SCAN: Functional integration of a Scanning Electron Microscope and an energy-dispersive x-ray analyser

1989 ◽  
Vol 47 ◽  
pp. 56-57
Author(s):  
Marc H. Peeters ◽  
Max T. Otten
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
High Speed ◽  
High Performance ◽  
Functional Integration ◽  
Energy Dispersive ◽  
X Rays ◽  
X Ray ◽  
High Speed Analysis ◽  
Scanning Electron

Over the past decades, the combination of energy-dispersive analysis of X-rays and scanning electron microscopy has proved to be a powerful tool for fast and reliable elemental characterization of a large variety of specimens. The technique has evolved rapidly from a purely qualitative characterization method to a reliable quantitative way of analysis. In the last 5 years, an increasing need for automation is observed, whereby energy-dispersive analysers control the beam and stage movement of the scanning electron microscope in order to collect digital X-ray images and perform unattended point analysis over multiple locations.The Philips High-speed Analysis of X-rays system (PHAX-Scan) makes use of the high performance dual-processor structure of the EDAX PV9900 analyser and the databus structure of the Philips series 500 scanning electron microscope to provide a highly automated, user-friendly and extremely fast microanalysis system. The software that runs on the hardware described above was specifically designed to provide the ultimate attainable speed on the system.

scholarly journals Testing the disk-corona interplay in radiatively-efficient broad-line AGN

2019 ◽  
Vol 628 ◽  
pp. A135 ◽  
Author(s):  
R. Arcodia ◽  
A. Merloni ◽  
K. Nandra ◽  
G. Ponti
Keyword(s):  
Accretion Disk ◽  
Reference Sample ◽  
Selection Effect ◽  
Galactic Nuclei ◽  
Theoretical Explanation ◽  
X Rays ◽  
Broad Line ◽  
Coronal Emission ◽  
X Ray ◽  
Intrinsic Scatter

The correlation observed between monochromatic X-ray and UV luminosities in radiatively-efficient active galactic nuclei (AGN) lacks a clear theoretical explanation despite being used for many applications. Such a correlation, with its small intrinsic scatter and its slope that is smaller than unity in log space, represents the compelling evidence that a mechanism regulating the energetic interaction between the accretion disk and the X-ray corona must be in place. This ensures that going from fainter to brighter sources the coronal emission increases less than the disk emission. We discuss here a self-consistently coupled disk-corona model that can identify this regulating mechanism in terms of modified viscosity prescriptions in the accretion disk. The model predicts a lower fraction of accretion power dissipated in the corona for higher accretion states. We then present a quantitative observational test of the model using a reference sample of broad-line AGN and modeling the disk-corona emission for each source in the LX − LUV plane. We used the slope, normalization, and scatter of the observed relation to constrain the parameters of the theoretical model. For non-spinning black holes and static coronae, we find that the accretion prescriptions that match the observed slope of the LX − LUV relation produce X-rays that are too weak with respect to the normalization of the observed relation. Instead, considering moderately-outflowing Comptonizing coronae and/or a more realistic high-spinning black hole population significantly relax the tension between the strength of the observed and modeled X-ray emission, while also predicting very low intrinsic scatter in the LX − LUV relation. In particular, this latter scenario traces a known selection effect of flux-limited samples that preferentially select high-spinning, hence brighter, sources.

scholarly journals Non-equilibrium processes in martensitic phase transformations by X-ray photon correlation spectroscopy

2015 ◽  
Vol 1754 ◽  
pp. 141-146
Author(s):  
Michael Widera ◽  
Uwe Klemradt
Keyword(s):  
Photon Correlation Spectroscopy ◽  
Time Correlation ◽  
Correlation Spectroscopy ◽  
X Rays ◽  
Photon Correlation ◽  
X Ray ◽  
Equilibrium Dynamics ◽  
Speckle Patterns ◽  
Martensitic Phase Transformations ◽  
Non Equilibrium

ABSTRACTThrough undulator sources at 3rd generation synchrotrons, highly coherent X-rays with sufficient flux are nowadays routinely available, which allow carrying over photon correlation spectroscopy (PCS) from visible light to the X-ray regime. X-ray photon correlation spectroscopy (XPCS) is based on the auto-correlation of X-ray speckle patterns during the temporal evolution of a material and provides access both to equilibrium and non-equilibrium properties of materials at the Angstrom scale. Owing to technical limitations (detector readout), XPCS has typically been used for the detection of slow dynamics on the scale of seconds. The variety of scattering geometries employed in conventional X-ray analysis can be combined with XPCS. In this work, we report on bulk diffraction (XRD) used to study the prototypical shape memory alloy Ni63Al37 undergoing a structural, diffusionless (martensitic) transformation. Two-time correlation functions reveal non-equilibrium dynamics superimposed with microstructural avalanches.

Compton Scattering Artifacts in Electron Excited X-Ray Spectra Measured with a Silicon Drift Detector

2011 ◽  
Vol 17 (6) ◽  
pp. 903-910 ◽  
Author(s):  
Nicholas W.M. Ritchie ◽  
Dale E. Newbury ◽  
Abigail P. Lindstrom
Keyword(s):  
Trace Element ◽  
Compton Scattering ◽  
Trace Element Analysis ◽  
X Rays ◽  
Silicon Drift Detector ◽  
Element Analysis ◽  
X Ray ◽  
Peak Absorption ◽  
Small Feature ◽  
Nonideal Behavior

AbstractArtifacts are the nemesis of trace element analysis in electron-excited energy dispersive X-ray spectrometry. Peaks that result from nonideal behavior in the detector or sample can fool even an experienced microanalyst into believing that they have trace amounts of an element that is not present. Many artifacts, such as the Si escape peak, absorption edges, and coincidence peaks, can be traced to the detector. Others, such as secondary fluorescence peaks and scatter peaks, can be traced to the sample. We have identified a new sample-dependent artifact that we attribute to Compton scattering of energetic X-rays generated in a small feature and subsequently scattered from a low atomic number matrix. It seems likely that this artifact has not previously been reported because it only occurs under specific conditions and represents a relatively small signal. However, with the advent of silicon drift detectors and their utility for trace element analysis, we anticipate that more people will observe it and possibly misidentify it. Though small, the artifact is not inconsequential. Under some conditions, it is possible to mistakenly identify the Compton scatter artifact as approximately 1% of an element that is not present.

X-ray emission analysis in the electron microscope

1982 ◽  
Vol 305 (1491) ◽  
pp. 535-543 ◽  
Keyword(s):  
Electron Microscope ◽  
Atomic Number ◽  
Critical Examination ◽  
X Rays ◽  
Emission Analysis ◽  
X Ray ◽  
Analytical Precision

The technique by which sample-emitted X-rays are recorded in the electron microscope is assessed. Although the method is relatively insensitive for elements of low atomic number, its applicability in the field of s imultaneous structural and compositional investigations is discussed, together with a critical examination of the analytical precision possible. Various examples of its use are described, including some where structure and stoichiometry can be determined in crystals containing fewer than 10 10 atoms.

Nanocrystallite model for amorphous calcium carbonate

2014 ◽  
Vol 47 (5) ◽  
pp. 1651-1657 ◽  
Author(s):  
P. Rez ◽  
S. Sinha ◽  
A. Gal
Keyword(s):  
Electron Microscope ◽  
Calcium Carbonate ◽  
Electron Diffraction ◽  
Relative Intensity ◽  
Ir Spectrum ◽  
X Rays ◽  
High Angle ◽  
Amorphous Calcium Carbonate ◽  
Optical Birefringence ◽  
X Ray

Amorphous calcium carbonate phases, either synthesized artificially or generated biogenically, can be identified from broadened peaks in X-ray or electron diffraction profiles. It is conceivable that randomly oriented nanocrystals, approximately 1 nm in size, could give rise to coherent diffraction profiles that are characterized as amorphous. The coherent diffraction profiles for 200 keV electrons, as might be used in an electron microscope, and Cu Kα X-rays were calculated for needle-shaped calcite crystals bounded by \{ {11\overline 21}\} facets and rhomb-shaped crystals bounded by \{ {10\overline 14} \} facets. Crystals of about 1.0 nm in size gave a profile that is consistent with the X-ray measurements of amorphous calcium carbonate. The relative intensity of high-angle broadened peaks and changes in the IR spectrum are best explained by disorder in the nanocrystallites. The presence of randomly oriented nanocrystallites also explains the lack of optical birefringence.

X-Ray Safety of Electron Microscopes

1972 ◽  
Vol 30 ◽  
pp. 414-417
Author(s):  
D. F. Parsons ◽  
V. A. Phillips ◽  
J. S. Lally
Keyword(s):  
Electron Microscope ◽  
Atomic Number ◽  
Health Hazards ◽  
X Rays ◽  
X Ray ◽  
Metal Parts ◽  
Voltage Electron ◽  
Two Factors ◽  
Electron Microscopes ◽  
Acceleration Voltage

This investigation was initiated to provide the first assessment, from the users viewpoint, of the health hazards of X-ray leakages from conventional (40-200 Kv acceleration voltage) electron microscopes. Scanning microscopes were not considered at this point.X-rays are produced in the electron microscope when the beam strikes metal parts of the instrument. The degree of X-ray leakage depends on two factors--the intensity of the X-ray source and the amount of metal shielding surrounding it. The efficiency of total (continuous and characteristic) X-ray production is approximately proportional to the atomic number of the metal and to the acceleration voltage (platinum apertures are three times as efficient as the iron of pole pieces). However, the fraction of beam striking the metal has to be taken into account and the efficiency of the shielding. The thickness (number of Half Value Layers), the effect of absorption edges on X-ray transmission, and the cracks or openings in the shielding all have to be taken into account.

Routine Determination of X-Ray Detector Efficiencies Using Submicron Spheres of Pure Materials

1985 ◽  
Vol 43 ◽  
pp. 416-417
Author(s):  
Thomas F. Kelly
Keyword(s):  
Electron Microscope ◽  
Energy Range ◽  
Transmission Electron Microscope ◽  
Weight Fraction ◽  
Characteristic Line ◽  
X Rays ◽  
Detector Efficiency ◽  
X Ray ◽  
Transmission Electron

The purpose of this paper is to outline an approach to routine determination of x-ray detector efficiencies over the entire applicable energy range that may be used on any transmission electron microscope.BACKGROUNDThe quantification of x-ray intensities using the ratio technique can be accomplished [see, for example, 1] using a relation of the form:Here, for element A, CA is the composition in the sample as a weight fraction, kA is the x-ray generation constant (see below) which contains only sample-dependent information, eA is the detector efficiency for characteristic x-rays which contains only detector-dependent information, and lA is the measured x-ray intensity in a characteristic line.

Sign in / Sign up

Export Citation Format

Share Document