scholarly journals Исследование контаминационной пленки, формирующейся под действием электронного пучка

2019 ◽  
Vol 89 (9) ◽  
pp. 1412
Author(s):  
К.Н. Орехова ◽  
Ю.М. Серов ◽  
П.А. Дементьев ◽  
Е.В. Иванова ◽  
В.А. Кравец ◽  
...  
Keyword(s):  
Electron Beam ◽  
Absorption Coefficient ◽  
Electron Probe ◽  
Film Formation ◽  
Emission Lines ◽  
X Ray ◽  
Characteristic Emission ◽  
Carbon Coated ◽  
Hydrocarbon Film

During the study of materials on electron probe devices in the field of the electron beam, a contamination hydrocarbon film is formed, which influences the results of experiments. In this paper, we studied the effect of a contamination film formed on carbon-coated dielectric samples on the intensity of cathodoluminescence and X-ray characteristic emission lines. The absorption coefficient of the film for the visible and UV ranges was determined. The mechanism of film formation for various parameters of the electron beam is discussed.

Electron Probe X-Ray Analysis of Nanofilms at Off-Normal Incidence of the Electron Beam

2018 ◽  
Vol 54 (14) ◽  
pp. 1417-1420
Author(s):  
S. A. Darznek ◽  
V. B. Mityukhlyaev ◽  
P. A. Todua ◽  
M. N. Filippov
Keyword(s):  
Electron Beam ◽  
Electron Probe ◽  
Normal Incidence ◽  
X Ray

scholarly journals Measurements of L‐shell X‐ray emission lines of neonlike europium on an electron beam ion trap

2019 ◽  
Vol 49 (1) ◽  
pp. 21-24 ◽  
Author(s):  
Peter Beiersdorfer ◽  
Natalie Hell ◽  
Dmytro Panchenko ◽  
Greg V. Brown ◽  
Elmar Träbert ◽  
...  
Keyword(s):  
Electron Beam ◽  
Ion Trap ◽  
Emission Lines ◽  
X Ray ◽  
Electron Beam Ion Trap

Compositional imaging in the Electron Microscope

1991 ◽  
Vol 49 ◽  
pp. 2-3
Author(s):  
C. E. Lyman
Keyword(s):  
Electron Microscopy ◽  
Electron Beam ◽  
Electron Microscope ◽  
Data Collection ◽  
Electron Probe ◽  
Compositional Data ◽  
Fine Scale ◽  
Bulk Specimen ◽  
Beam Position ◽  
X Ray

Imaging of elemental distributions on a fine scale is one of the triumphs of electron microscopy. Compositional imaging frees the operator from the necessity of making decisions about which features contain the elements of interest. Elements in unexpected locations, or in unexpected association with other elements, may be found easily without operator bias as to where to locate the electron probe for compositional data collection. This technique may be applied to bulk or thin specimens using a variety of composition-sensitive signals as shown in Figure 1.Cosslett and Duncumb obtained the first such compositional image in an electron microprobe modified to scan the electron beam and collect a characteristic x-ray signal as a function of beam position. Early images of this type were called x-ray “dot maps” and provided a qualitative indication of the location of elements on a flat polished bulk specimen to a spatial resolution of about 1 μm.

Trauma causes heterogeneous compositional shifts in spinal cord

1992 ◽  
Vol 50 (2) ◽  
pp. 1594-1595
Author(s):  
Lyle G. Walsh ◽  
William B. Greene
Keyword(s):  
Spinal Cord ◽  
Electron Probe ◽  
Healthy People ◽  
Spinal Cord Trauma ◽  
Liquid Propane ◽  
X Ray ◽  
Cold Stage ◽  
Freeze Dried ◽  
Carbon Coated

Each year spinal cord trauma causes thousands of otherwise healthy people to be permanently disabled. In most cases, the axonal tracts are not mechanically severed. Instead, unknown mechanisms cause a progressive segmental necrosis. In this study, we use electron probe x-ray microanalysis, EPMA, to examine the composition of the dorsal axons and myelin 6 hours after mild and moderate trauma in order to identify the subcellular changes induced by trauma. Laminectomies were performed on anesthetized rats and sham, 6 g-cm or 20 g-cm trauma was delivered and the wound closed. Six hours after trauma the rats were again anesthetized, the dura was removed and the spinal cord was frozen in situ with a 100 psi jet of super-cooled liquid propane. Cryosections, 200 nm thick, were cut at -120°C and placed on carbon coated formvar covered folding copper grids. Samples were freeze dried and analyzed within an Hitachi H-7000 STEM on a Be tipped, GATAN, analytical cold stage with a 2-4 nA, 125 KeV beam.

The X-Ray Spectrographic Analysis of Thin Films by the Milliprobe Technique

1961 ◽  
Vol 5 ◽  
pp. 512-515 ◽  
Author(s):  
Robert D. Sloan
Keyword(s):  
Thin Films ◽  
Electron Beam ◽  
Electron Probe ◽  
Spectrographic Analysis ◽  
X Ray ◽  
Electron Probe Microanalyzer ◽  
Bulk Production

AbstractFrequently it is desirable to perform an X-ray spectrographic analysis on an area of a specimen which is considerably smaller than that normally irradiated in bulk-production spectrographs. Ideally, one would turn to an electron-beam microanalyzer for this type of analysis. Unfortunately, there are few of us who can justify the expenditure necessary to equip our laboratories with this instrument. Therefore, a compromise measure has been arrived at which permits the analyst to examine an area many magnitudes smaller than that obtainable from production spectrographs and many magnitudes less expensive than that encountered in electron-probe microanalyzer instrumentation.

Recent Developments in the Study of Grain Boundary Segregation by Wavelength Dispersive X-Ray Spectroscopy (WDS)

2011 ◽  
Vol 309-310 ◽  
pp. 39-44
Author(s):  
Pawel Nowakowski ◽  
Frédéric Christien ◽  
Marion Allart ◽  
René Le Gall
Keyword(s):  
Electron Beam ◽  
Fracture Surface ◽  
Grain Boundary ◽  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
Boundary Segregation ◽  
Normal Incidence ◽  
Grain Boundary Segregation ◽  
X Ray ◽  
Recent Developments

It was recently shown [1] that EMPA-WDS (Electron Probe MicroAnalysis by Wavelength Dispersive X-ray Spectroscopy) can be used to detect and to accurately quantify monolayer surface and grain boundary segregation. This paper presents the last developments of this application. It focuses on the measurement of sulphur grain boundary segregation in nickel on fractured surfaces. A special attention was paid to the quantification of the sulphur coverage, taking into account the non-normal incidence of the electron beam on a fracture surface. Sulphur grain boundary segregation kinetics was measured at 750°C in nickel to document the quantitative possibilities of the technique.

Factors Affecting Quantitative Analysis Error in ESEM-EDS

2000 ◽  
Vol 6 (S2) ◽  
pp. 790-791
Author(s):  
R. A. Carlton ◽  
C. E. Lyman ◽  
J. E. Roberts
Keyword(s):  
Electron Beam ◽  
Target Location ◽  
Primary Electron ◽  
Environmental Scanning ◽  
X Rays ◽  
Factors Affecting ◽  
X Ray ◽  
Carbon Coated ◽  
Sample Chamber ◽  
Analysis Error

Standard Reference Material (SRM) 482 of the National Institute of Standards and Technology is a set of 6 gold/copper wires, ranging in concentration from 0 to 100% Cu in 20% steps, intended for calibration studies of electron beam microanalyzers. This is an appropriate standard to test the accuracy of energy dispersive x-ray spectrometry (EDS) in the Environmental Scanning Electron Microscope (ESEM). While the presence of the gas in the sample chamber gives the ESEM its unique capabilities, it also is the source of complications to x-ray spectrometry. The gas can spread the primary electron beam into a wide skirt of electrons with the consequent production of x-rays many micrometers from the target location of the beam.The six wires (∼ 500 jam in diameter) were embedded and polished in one epoxy mount. The mount was carbon coated in one set of experiments. The coating was removed and the sample retested.

Characteristic and Continuum Fluorescence in Electron Beam X-ray Microanalysis

1999 ◽  
Vol 5 (S2) ◽  
pp. 562-563
Author(s):  
C.E. Nockolds
Keyword(s):  
Electron Beam ◽  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
Mathematical Framework ◽  
X Rays ◽  
Correction Procedure ◽  
X Ray ◽  
Exponential Term ◽  
Accurate Expression ◽  
Original Formula

Of the different aspects of electron probe microanalysis(EPMA)which were studied by Castaing during his doctorate the work on characteristic x-ray fluorescence was the most definitive. In his thesis, which was completed in 1951, Castaing established the physical and mathematical framework for a correction procedure for fluorescence which is essentially still used in EPMA today. Much of the effort since then has been in refining and improving the accuracy of the correction and extending the scope of the correction to a wider range of specimen types. The Castaing formula was developed for the case of a K x-ray from element A being excited by a K xray from element B (K-K fluorescence) and in 1965 Reed extended the range of the correction by including the K-L, L-L and L-K interactions. In the same paper Reed also introduced the expression from Green and Cosslett for the calculation of K intensities, which was believed to be more accurate than the expression used by Castaing. The original formula included a somewhat unrealistic exponential term to allow for the depth of the production of the primary x-rays and a number of workers have tried replacing this term with a more accurate expression, however, in general this has led to only small changes in the final correction. Reed also simplified the formula in order to make the calculation easier in the days before fast computers; in particular he replaced the jump ratio variable by two constants, one for the K-shell and one for the L-shell. Much later Heinrich showed that this simplification was no longer necessary and that the jump ratio could in fact be calculated directly.

Improving the Analtical Accuracy in the Analysis of Particles by Employing Low Voltage Analysis:

2000 ◽  
Vol 6 (S2) ◽  
pp. 924-925
Author(s):  
JA Small ◽  
JT Armstrong
Keyword(s):  
Electron Beam ◽  
Electron Probe ◽  
Low Voltage ◽  
X Rays ◽  
Relative Uncertainty ◽  
Particle Volume ◽  
X Ray ◽  
Uncertainty Estimates ◽  
Corrected Data ◽  
Particle Geometry

The energy of the electron beam, in conventional electron probe microanalysis, is generally in the range of 15-25 keV which provides the necessary overvoltage to excite efficiently the K and L x-ray lines for elements with atomic numbers in the range of about 5-83. One of the primary microanalytical methods for obtaining compositional information on particles is X-ray analysis in the electron probe and these same voltage criteria have been applied to the procedures developed for this purpose. The main difference in analytical procedures for bulk samples and particles is that corrections have to be applied to the particle k-ratios or calculated compositions to compensate for: 1) the penetration or scattering of electrons out of the particle volume and 2) variations in the absorption due to particle geometry of x-rays less than about 3 keV. In general, particle corrections improve the accuracy and reduce the relative uncertainty estimates from several tens of percent for uncorrected data to about 10% for corrected data.

scholarly journals Hit detection in serial femtosecond crystallography using X-ray spectroscopy of plasma emission

IUCrJ ◽  
2017 ◽  
Vol 4 (6) ◽  
pp. 778-784 ◽  
Author(s):  
H. Olof Jönsson ◽  
Carl Caleman ◽  
Jakob Andreasson ◽  
Nicuşor Tîmneanu
Keyword(s):  
Protein Structures ◽  
Emission Spectra ◽  
Emission Lines ◽  
High Rate ◽  
Plasma Emission ◽  
X Ray ◽  
Carrier Liquid ◽  
Characteristic Emission ◽  
Laser Sources ◽  
Serial Femtosecond Crystallography

Serial femtosecond crystallography is an emerging and promising method for determining protein structures, making use of the ultrafast and bright X-ray pulses from X-ray free-electron lasers. The upcoming X-ray laser sources will produce well above 1000 pulses per second and will pose a new challenge: how to quickly determine successful crystal hits and avoid a high-rate data deluge. Proposed here is a hit-finding scheme based on detecting photons from plasma emission after the sample has been intercepted by the X-ray laser. Plasma emission spectra are simulated for systems exposed to high-intensity femtosecond pulses, for both protein crystals and the liquid carrier systems that are used for sample delivery. The thermal radiation from the glowing plasma gives a strong background in the XUV region that depends on the intensity of the pulse, around the emission lines from light elements (carbon, nitrogen, oxygen). Sample hits can be reliably distinguished from the carrier liquid based on the characteristic emission lines from heavier elements present only in the sample, such as sulfur. For buffer systems with sulfur present, selenomethionine substitution is suggested, where the selenium emission lines could be used both as an indication of a hit and as an aid in phasing and structural reconstruction of the protein.

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