Artykuły w czasopismach: „Plural Scattering”

1

Kawrakow, I. "Electron transport: multiple and plural elastic scattering". Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 108, nr 1-2 (styczeń 1996): 23–34. http://dx.doi.org/10.1016/0168-583x(95)01046-7.

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Su, D. S., H. F. Wang i E. Zeitler. "The influence of plural scattering on EELS elemental analysis". Ultramicroscopy 59, nr 1-4 (lipiec 1995): 181–90. http://dx.doi.org/10.1016/0304-3991(95)00027-x.

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Egerton, R. F., i S. C. Cheng. "Elemental analysis of telatively thick specimens by EELS". Proceedings, annual meeting, Electron Microscopy Society of America 50, nr 2 (sierpień 1992): 1248–49. http://dx.doi.org/10.1017/s0424820100130870.

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Core-loss spectra of thicker specimens are strongly influenced by plural scattering. Plural inelastic events increase the background Ib underneath an ionization edge by an amount dependent on t/λ, t being the specimen thickness and λ the total-inelastic mean free path. However, plural scattering also contributes to the integral core-loss signal Ic. In fact, if the latter were integrated over a sufficiently large energy window Δ, the signal/background ratio (SBR=IC/Ib) might be expected to be independent of t.Figure 1 shows K-edge signal/background ratios for elemental carbon and silicon, presented as measured data points (for a collection semi-angle of l0mrad, 120keV incident energy and Δ=100eV) and as solid curves calculated by convolving a power-law edge profile with a delta-function approximation of the low-loss region. For silicon, SBR falls off more slowly with increasing t/λ, as expected from its higher edge energy. This trend is confirmed by measurements on amorphous silicon dioxide depicted in Fig.2, which shows the signal/background ratios of the oxygen and silicon K-edges as a function of thickness.

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Giangrandi, S., K. Arstila, B. Brijs, T. Sajavaara, A. Vantomme i W. Vandervorst. "Considerations about multiple and plural scattering in heavy-ion low-energy ERDA". Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 267, nr 11 (czerwiec 2009): 1936–41. http://dx.doi.org/10.1016/j.nimb.2009.03.105.

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Arstila, K., T. Sajavaara i J. Keinonen. "Monte Carlo simulation of multiple and plural scattering in elastic recoil detection". Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 174, nr 1-2 (marzec 2001): 163–72. http://dx.doi.org/10.1016/s0168-583x(00)00435-3.

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Bielajew, Alex F. "Plural and multiple small-angle scattering from a screened Rutherford cross section". Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 86, nr 3-4 (kwiecień 1994): 257–69. http://dx.doi.org/10.1016/0168-583x(94)95288-4.

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Bauer, P., E. Steinbauer i J. P. Biersack. "The width of an RBS spectrum: influence of plural and multiple scattering". Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 64, nr 1-4 (luty 1992): 711–15. http://dx.doi.org/10.1016/0168-583x(92)95563-7.

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FUJIHARA, Kento, Yusaku EMOTO, Hiroshi ITO, Naomi KANEKO, Hideyuki KANEKO, Hideyuki KAWAI, Atsushi KOBAYASHI i Takahiro MIZUNO. "Evaluation of Position Resolution for a Prototype Whole-Body PET Detector Based on Suppressing Backgrounds by Compton Scattering". EPJ Web of Conferences 170 (2018): 09004. http://dx.doi.org/10.1051/epjconf/201817009004.

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Existing PET (Positron Emission Tomography) systems make clear images in demonstration (measuring small PET reagent in pure water), however images in real diagnosis become unclear. The authors suspected that this problem was caused by Compton scattering in a detector. When PET systems observe plural photomultiplier tube outputs, an original emission point is regarded as centroid of the outputs. However, even if plural emission in Compton scattering occur, these systems calculate original point in the same way as single emission. Therefore, the authors considered that rejecting Compton scattering events makes PET systems much better, and made prototype counter. Main components of the prototype counter are plate-like high-growth-rate (HGR) La-GPS scintillators and wavelength shifting fibers (WLSF). HGR crystals grow 10 times as fast as a mono-crystal (a normal mono-crystal grows at 2 – 3 mm an hour). Thus, it includes microbubble and its transparency get worth. Consequently, HGR crystals usually are not used in radiation measuring instruments. However, this time they are used on the purpose. Because of their low transparency, scintillation lights come out right above and right under of emission position. Therefore, Compton scattering events is rejected easily. The prototype detector has an effective area of 300 by 300 square mm. The detector consists of 24 layers. One layer consists of HGR La-GPS scintillator of 1 mm thickness. Top and bottom surface of scintillator were covered by dual sheets of WLSF with a diameter of 0.2 mm. Sheets of WLSF on top and bottom of the scintillator make a right angle with each other, and measure X- and Y-components. Z-component is measured by difference of WLSF outputs between top and bottom. If plural layers output signals, this counter regards the event as Compton scattering event, and reject the event. Even if only a layer output signals, the event is rejected when number output signals from WLSF is more than 1.5 times of single emission. Material cost of this system is, 0.2M$ for HGR La-GPS, 0.03M$ for WLSF, 0.03M$ for 600 units of 6 by 6 mm SiPM's, 0.12M$ for 12000 units of 1 by 1 mm SiPM's, and 0.09M$ for 1800 channel of signal readout circuits. Considering total cost, price of this PET will be set 1M$ or less. This idea was confirmed with numerical simulation and experimentation. In experimentation, position resolution in photoelectric absorption was 0.2 mm, and minimum distance that this detector could recognize plural emission in Compton scattering was 1 mm. In parallel, three kinds of model were made: a prototype detector, all the signals readout method, and resistance delay method. Simulation setting was 2 MBq/L in normal tissue and 10 MBq/L in cancer. As a result of simulation, a prototype detector identified 3 mm cancer, however the others made unclear image and was not able to identified cancer. That is to say, the prototype detector is able to reject Compton scattering events and inexpensive. Therefore, whole-body PET system with this detector must diagnose cancer with a diameter of 3 mm or more and be priced 1M$ or less

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Luo, Suichu, i David C. Joy. "A new method for quantitative analysis of EELS". Proceedings, annual meeting, Electron Microscopy Society of America 52 (1994): 950–51. http://dx.doi.org/10.1017/s0424820100172486.

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Techniques to remove plural scattering from electron energy loss spectra (EELS) are important in bot hmicroanalysis and other quantitative applications of electron spectroscopy. The techniques used are either based on convolution, or Fourier transform deconvolution, methods, in which either the elastic scattering angular correction or both elastic and inelastic angular corrections are not included. In this work we propose a new method based on both angular and energy loss three-dimension Poisson statistics which includes elastic and inelastic mixed angular scattering correction in order to obtain more accurate quantitative analysis for EELS.The electron scattering distribution determined by angular and energy loss three-dimension Poissonstatistics is given by:where IT is the total incident electron intensity; t is the sample thickness; λi, λe and λT are inelastic , elastic and total scattering mean free paths; Si (θ) and Se(θ) are normalized single inelastic and elastic angular scattering distributions respectively, F(E) is the single scattering normalized energy loss distribution.

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Narayan, Raman D., J. K. Weiss i Peter Rez. "Highly Automated Electron Energy-Loss Spectroscopy Elemental Quantification". Microscopy and Microanalysis 20, nr 3 (10.04.2014): 798–806. http://dx.doi.org/10.1017/s1431927614000567.

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AbstractA model-based fitting algorithm for electron energy-loss spectroscopy spectra is introduced, along with an intuitive user-interface. As with Verbeeck & Van Aert, the measured spectrum, rather than the single scattering distribution, is fit over a wide range. An approximation is developed that allows for accurate modeling while maintaining linearity in the parameters that represent elemental composition. Also, a method is given for generating a model for the low-loss background that incorporates plural scattering. Operation of the user-interface is described to demonstrate the ease of use that allows even nonexpert users to quickly obtain elemental analysis results.

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Egerton, R. F. "Developments in the processing of electron energy-loss spectra". Proceedings, annual meeting, Electron Microscopy Society of America 45 (sierpień 1987): 80–83. http://dx.doi.org/10.1017/s0424820100125385.

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Because the total-inelastic mean free path is generally comparable to the specimen thickness, energy-loss spectra recorded in a TEM contain appreciable contributions from plural (or multiple) scattering, which imparts no additional information but may distort or submerge characteristic features. Happily, the single-scattering spectrum S(E) can be derived from a recorded spectrum by the method of Fourier-log deconvolution; if j(f) and z(f) are the Fourier transforms of the recorded data J(E) and of the zero-loss peak Z(E), the Fourier transform s(f) of the single-scattering distribution S(E) is given by:s(f) = r(f) loge [j(f)/z(f)] (1)Here, r(f) is the Fourier transform of a bell-shaped reconvolution function R(E); if r(f) were omitted from Eq.(l), s(f) would correspond to an ‘ideal’ single-scattering distribution, unbroadened by the instrumental resolution △E.

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Johnston, P. N., R. D. Franich, I. F. Bubb, M. El Bouanani, D. D. Cohen, N. Dytlewski i R. Siegele. "The effects of large angle plural scattering on heavy ion elastic recoil detection analysis". Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 161-163 (marzec 2000): 314–17. http://dx.doi.org/10.1016/s0168-583x(99)00977-5.

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Egerton, R. F., i Z. L. Wang. "Plural-scattering deconvolution of electron energy-loss spectra recorded with an angle-limiting aperture". Ultramicroscopy 32, nr 2 (luty 1990): 137–47. http://dx.doi.org/10.1016/0304-3991(90)90032-h.

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14

Luo, Suichu, John R. Dunlap, Richard W. Williams i David C. Joy. "Local thickness determination by Electron Energy Loss Spectroscopy". Proceedings, annual meeting, Electron Microscopy Society of America 52 (1994): 944–45. http://dx.doi.org/10.1017/s0424820100172450.

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In analytical electron microscopy, it is often important to know the local thickness of a sample. The conventional method used for measuring specimen thickness by EELS is:where t is the specimen thickness, λi is the total inelastic mean free path, IT is the total intensity in an EEL spectrum, and I0 is the zero loss peak intensity. This is rigorouslycorrect only if the electrons are collected over all scattering angles and all energy losses. However, in most experiments only a fraction of the scattered electrons are collected due to a limited collection semi-angle. To overcome this problem we present a method based on three-dimension Poisson statistics, which takes into account both the inelastic and elastic mixed angular correction.The three-dimension Poisson formula is given by:where I is the unscattered electron intensity; t is the sample thickness; λi and λe are the inelastic and elastic scattering mean free paths; Si (θ) and Se(θ) are normalized single inelastic and elastic angular scattering distributions respectively ; F(E) is the single scattering normalized energy loss distribution; D(E,θ) is the plural scattering distribution,

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Kitamura, Toshiaki. "Numerical Analysis of Ridged-Circular Nanoaperture for Near-Field Optical Disk". ISRN Optics 2013 (29.10.2013): 1–6. http://dx.doi.org/10.1155/2013/543960.

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A ridged-circular nanoaperture is investigated through three-dimensional (finite-difference time-domain) FDTD method. The motion equations of free electrons are inserted to analyze a metallic material. The electromagnetic field distributions of optical near-field around the aperture are investigated. The phase change disk illuminated by a near-field optical light through a ridged-circular nanoaperture is also analyzed. The far-field scattering patterns from the phase change disk and the crosstalk characteristics between plural marks are studied.

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Moore, K. T., E. A. Stach, J. M. Howe, D. C. Elbert i D. R. Veblen. "A Tilting Procedure to Enhance Compositional Contrast and Reduce Residual Bragg Contrast in EFTEM Imaging of Planar Interfaces". Microscopy and Microanalysis 6, S2 (sierpień 2000): 156–57. http://dx.doi.org/10.1017/s1431927600033274.

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When acquiring energy-filtered TEM (EFTEM) images of a crystalline material, the detrimental effects of diffraction contrast can often be seen in raw energy-filtered images (EFI) (i.e., pre-edge and post-edge images), jump-ratio images and elemental maps as residual diffraction contrast. Residual diffraction contrast occurs in raw EFI because of plural scattering (i.e., inelastic-elastic and elastic-inelastic electron scattering) and in jump-ratio images and elemental maps because background removal procedures often are unable to completely account for intensity changes due to dynamical effects (elastic scattering) that occur between pre-edge and post-edge images acquired at different energy losses.It is demonstrated in these experiments that, when examining a planar interface, EFTEM images have increased compositional contrast and decreased residual diffraction contrast when the sample is oriented so that the interface is parallel to the electron beam, but not directly on a zone axis.

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Wang, Y. Y., Z. Shao, R. Ho, A. V. Somlyo i A. P. Somlyo. "Quantitative EELS mapping of biological thin sections". Proceedings, annual meeting, Electron Microscopy Society of America 50, nr 2 (sierpień 1992): 1568–69. http://dx.doi.org/10.1017/s0424820100132479.

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X-ray microanalysis and electron energy loss spectroscopy are reliable methods for determining at high spatial resolution the local composition of biological materials. EELS imaging, although potentially more sensitive than X-ray analysis, is complicated by the large background of EELS spectra. The conventional power law fitting of the EELS background can only be used for analysis of high concentrations and/or very thin sections (t< 0.3 λ) and it is not reliable for mapping low elemental concentrations. For the detection of low elemental concentrations at high spatial resolution, the background subtraction of the EELS spectrum and correction of long term microscope drift are critical, and limit the use of conventional energy filtered transmission electron microscopy. Therefore, we used energy filtered STEM with multiple least squares fitting, including the plural plasmon contribution to the background, to obtain quantitative phosphorus (P) and calcium (Ca) concentration maps of cryosections.The failure of the power law is due to the plural scattering contributions to the Background.

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Leapman, R. D., i C. R. Swyt. "Quantitative Electron Energy Loss Mapping". Proceedings, annual meeting, Electron Microscopy Society of America 43 (sierpień 1985): 404–5. http://dx.doi.org/10.1017/s0424820100118898.

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The intensity of a characteristic electron energy loss spectroscopy (EELS) image does not, in general, directly reflect the elemental concentration. In fact, the raw core loss image can give a misleading impression of the elemental distribution. This is because the measured core edge signal depends on the amount of plural scattering which can vary significantly from region to region in a sample. Here, we show how the method for quantifying spectra due to Egerton et al. can be extended to maps.

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Corstens, J. M., W. Knulst, O. J. Luiten i M. J. van der Wiel. "An efficient method for calculating plural scattering of relativistic electrons in thin foils and multilayers". Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 222, nr 3-4 (sierpień 2004): 437–44. http://dx.doi.org/10.1016/j.nimb.2004.04.163.

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Sölkner, G., i P. Schattschneider. "A computational test for the removal of plural scattering from angle-resolved energy loss spectra". Journal of Microscopy 137, nr 3 (marzec 1985): 275–80. http://dx.doi.org/10.1111/j.1365-2818.1985.tb02584.x.

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Egerton, R. F., i S. H. Liou. "A remarkable property of the angular distribution of plural inelastic scattering, with benign consequences for the deconvolution of electron energy-loss spectra". Proceedings, annual meeting, Electron Microscopy Society of America 47 (6.08.1989): 380–81. http://dx.doi.org/10.1017/s0424820100153877.

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Electrons which have been inelastically scattered two or more times during passage through a thin specimen are known to be distributed more broadly in angle than those which are scattered only once. However, the literature contains no simple guide or analytical formula for the plural-scattering angular distribution. We decided to calculate this distribution by two-dimensional self-convolution of the single-scattering angular distribution, taking the latter to be a Lorentzian function: with characteristic angle ΘE and with an abrupt cut-off of the intensity at scattering angle Θ = Θc.The results are given in Fig. 1 in integral form: Fn(β) is the fraction of the electrons (which have been scattered n times) collected by an on-axis aperture of semi-angle β. Also shown in Fig. 1 are dashed curves representing the square and cube of F1. The close correspondence between the calculated points (F2 and F3) and the dashed curves is noteworthy. Similar agreement was obtained for cut-off angles in the range 50ΘE to 200ΘE, typical of most materials.

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Thomas, P. J., i P. A. Midgley. "Image-spectroscopy – II. The removal of plural scattering from extended energy-filtered series by Fourier deconvolution". Ultramicroscopy 88, nr 3 (sierpień 2001): 187–94. http://dx.doi.org/10.1016/s0304-3991(01)00078-x.

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Egerton, R. F., i S. C. Cheng. "Thickness Measurement by EELS". Proceedings, annual meeting, Electron Microscopy Society of America 43 (sierpień 1985): 398–99. http://dx.doi.org/10.1017/s0424820100118862.

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Electron energy-loss spectroscopy offers a rapid method of estimating the local thickness of a TEM specimen. The best-known procedure requires only measurement of the integrated intensity IO under the zero-loss peak and of the integral It under the whole spectrum (up to some suitable energy loss Δ). The thickness t is obtained from the formula:where λ(β) is the mean free path for inelastic scattering up to some angle β which is determined by the collection aperture (e.g. objective aperture in CTEM). In agreement with previous work we find that Eq. (1) is applicable over a wide range of thickness, typically 10-500 nm for EO = 100keV incident energy; see Fig. 1. Some deviation at large thickness might be expected as a result of the angular broadening produced by plural scattering, and because of contributions from electrons elastically scattered through angles greater than β.

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Bilde-Soerensen, J. B. "Hints To Correct For Skirt Effects From Plural Scattering When Doing EDS In A Low-Vacuum SEM". Microscopy Today 6, nr 3 (kwiecień 1998): 28. http://dx.doi.org/10.1017/s1551929500066864.

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Hunt, J. A., A. J. Strutt i D. B. Williams. "Quantitative light-element analysis using parallel EELS". Proceedings, annual meeting, Electron Microscopy Society of America 49 (sierpień 1991): 722–23. http://dx.doi.org/10.1017/s0424820100087926.

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Electron energy-loss spectrometry (EELS) is theoretically superior to x-ray emission spectrometry (XES) for light element microanalysis. The x-ray fluorescence yield decreases proportional to Z4, thus dramatically reducing characteristic x-ray production. However, the ionization cross section increases and so EELS becomes more efficient as Z decreases. Despite these advantages light element microanalysis using XES is often preferred to EELS. There are two major reasons why EELS is not more widespread. First, very thin specimens are needed to minimize plural scattering so quantification can proceed assuming single scattering. Secondly, many experimental variables make EELS difficult, particularly for microanalysts accustomed to the x-ray 'turn-key' approach to quantification. The former problem is being overcome with multiple least-squares (MLS) fitting deconvolution routines, while the latter has largely been solved by the development of parallel EELS (PEELS) and powerful analysis software. In this paper we show the quality of data currently available using PEELS.

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Thomas, P. J., i P. A. Midgley. "Image-Spectroscopy: New Developments and Applications". Microscopy and Microanalysis 5, S2 (sierpień 1999): 618–19. http://dx.doi.org/10.1017/s143192760001641x.

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The ability of modern TEMs to acquire a series of energy filtered images opens up new possibilities in energy loss compositional analysis. In particular, an electron spectroscopic imaging (ESI) series may be treated as a 2-D array of spectra whose resolution is dictated by the step size of the image series, as illustrated in Fig (a). This allows standard spectroscopic analysis techniques to be used on the extracted ‘image-spectra’, such as the removal of plural scattering by deconvolution. Examples of this are given in Fig (b) and (c), which show how Fourier-log and Fourier-ratio deconvolution can be used to recover the single scattering distribution (SSD) from both the low-loss and core-loss regions from a Cr specimen. A pure elemental sample is ideal for testing the validity of such analysis techniques for quantitative compositional mapping, and more details of this method will be published elsewhere. Further, for many simple metal systems, such as steels and alloys, and for simple semiconductors it is possible to model the plasmon contribution using a simple Drude-Lorentz model.

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Fisk Johnson, H., i M. S. Isaacson. "An efficient analytical method for calculating the angular and energy distribution of electrons which have undergone plural scattering in amorphous materials". Ultramicroscopy 26, nr 3 (styczeń 1988): 271–94. http://dx.doi.org/10.1016/0304-3991(88)90227-6.

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Bruley, J. "Applications of Multi-Variate Statistical Analysis of Spectrum Images to Microelectronic Devices". Microscopy and Microanalysis 7, S2 (sierpień 2001): 1158–59. http://dx.doi.org/10.1017/s143192760003186x.

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It is not uncommon for an electrical failure in a microelectronic device to be traced back to an individual resistive contact, such as a W contact lined by TiN to the underlying metal silicide [1]. Identifying the root cause of the defective cell then requires the capability of extracting interfacial chemistry and microstructure with near atomic resolution, which is achieved by recording EELS and EDX data either along 1-d lines or from 2-d arrays. EELS data are characterized by intrinsically low signal-to-background ratios and plural inelastic-scattering effects, which presents a challenge to the reliability of the methods used to extract quantitative information from a spectrum image. Commercially available software packages by Emispec and Gatan currently provide routines for power-law or polynomial background fits and allow the net counts under peaks or edges to be determined from each pixel. in both cases each spectrum in the series is processed in the same manner.

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Joy, David C. "Ultra-high resolution backscattered imaging". Proceedings, annual meeting, Electron Microscopy Society of America 50, nr 2 (sierpień 1992): 1284–85. http://dx.doi.org/10.1017/s042482010013105x.

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A recent paper by Ogura displays backscattered electron (BSE) images from a bulk, layered structure of AlAs/GaAs with repeat spacings of the order of 10nm. Typically BSE images are thought of as being inherently limited in resolution to a level which is of the order of a fraction of the Bethe range of the incident electrons, which for the beam energy and specimen used in these experiments would be of the order of 5 μm. The purpose of this paper is, therefore, to examine the conditions required for the nanometer level resolution achieved in this case.Backscattered electrons can be grouped into two classes, the BSI which are backscattered by a single high angle event soon after their entry into the specimen, and the BSII which are produced as the cumulative result of plural scattering. There is no sharp division between these groups but the two classes can be separated experimentally by energy filtering, since the BSI will have lost little energy in their short transit through the sample.

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Lu, Yun, i Joy David C. "Evaluation of particle effects in bremsstrahlung and in quantitative energy-dispersive x-ray microanalysis". Proceedings, annual meeting, Electron Microscopy Society of America 50, nr 2 (sierpień 1992): 1678–79. http://dx.doi.org/10.1017/s0424820100133023.

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The magnitude and the spectral form of bremsstrahlung signal contains much information about the target and is significantly influenced by the surface irregularities. By computer modelling, it is possible to extract the information to perform more accurate quantitative x-ray microanalysis for specimens with special geometries. In this research, bremsstrahlung spectra obtained from electron beams striking at selected locations of spherical particles were investigated by Monte Carlo simulations and experimental observations. The effects of surface geometries and the x-ray path lengths in the specimens on the variation of bremsstrahlung spectra and peak-to-background ratios were studied.The Monte Carlo electron trajectory calculations were determined with a screened Rutherford cross-section and a plural scattering model. The continuum x-ray depth profile is computed using Kramer's bremmstrahlung cross-section. The cross-section for inner shell ionization proposed by Green and Cosslett were employed for calculating characteristic x-rays. Bethe stopping power was determined by using the Luo-Joy modification at low energies. The mass absorption coefficient was calculated using Heinrich expression. The detector efficiency was determined experimentally.

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Kundmann, Michael K., i Gronsky Ronald. "Plasmon lineshape analysis in EELS of semiconductors". Proceedings, annual meeting, Electron Microscopy Society of America 46 (1988): 500–501. http://dx.doi.org/10.1017/s042482010010456x.

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Many materials display plasmon peaks in their low-loss EELS spectra. The plasmon peak shape, energy, and linewidth are characteristic of each material and are sensitive to the outer-shell electron density and details of the electronic band and energy-level structures. As these properties are a function not only of the composition but also the structure and chemistry of a sample, plasmon spectroscopy can potentially become a materials characterization tool which goes beyond the elemental analyses provided by EDXS and ionization-edge EELS. However, analysis of plasmon spectra requires considerably more sophistication than either of the aforementioned techniques due to the possibility of overlapping spectrum features, the prevalence of plural scattering, and the difficulty in detecting and characterizing the often subtle differences between the plasmon spectra of similar materials. As yet, no systematic approach to plasmon analysis analogous to that available commercially for EDXS or EELS core-edge analysis has been developed. We present here an approach which, for the simple case of semiconductors, makes some progress in this direction.

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Kugimoto, Daisuke, Aoi Taniguchi, Masaki Kinoshita i Isamu Akiba. "Effect of Molecular Architecture on Associating Behavior of Star-Like Amphiphilic Polymers Consisting of Plural Poly(ethylene oxide) and One Alkyl Chain". Polymers 13, nr 3 (31.01.2021): 460. http://dx.doi.org/10.3390/polym13030460.

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Associating behavior of star-like amphiphilic polymers consisting of two or three poly(ethylene oxide) (PEO) chains and one stearyl chain (C18) was investigated. Although the aggregation number (Nagg) of linear analogue of amphiphilic polymers monotonically decreased with increasing number-average molecular weight of PEO (Mn,PEO), the Nagg of micelles of star-like amphiphilic polymers with Mn,PEO = 550 g/mol was smaller than that with Mn,PEO = 750 g/mol, whereas that with Mn,PEO ≥ 750 g/mol showed general Mn,PEO dependence. Small-angle X-ray scattering analyses revealed that the occupied area of one PEO chain on the interface between hydrophobic core and corona layer in the micelles of star-like polymers was much narrower than that in the linear amphiphilic polymers. This result indica ted the PEO chains of star-like polymers partially took unfavorable conformation near the core–corona interface in polymer micelles. The effect of local conformation of PEO chains near the interface on the associating behavior became significant as Mn,PEO decreased. Therefore, in polymer micelles of star-like amphiphilic polymers containing PEO with Mn,PEO = 550 g/mol, the enlargement of occupied area of PEO on the core–corona interface should be caused to avoid the formation of unfavorable conformations of partial PEO chains, resulting in a decrease in Naggs.

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Du, Ming, Zichao (Wendy) Di, Dogˇa Gürsoy, R. Patrick Xian, Yevgenia Kozorovitskiy i Chris Jacobsen. "Upscaling X-ray nanoimaging to macroscopic specimens". Journal of Applied Crystallography 54, nr 2 (19.02.2021): 386–401. http://dx.doi.org/10.1107/s1600576721000194.

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Upscaling X-ray nanoimaging to macroscopic specimens has the potential for providing insights across multiple length scales, but its feasibility has long been an open question. By combining the imaging requirements and existing proof-of-principle examples in large-specimen preparation, data acquisition and reconstruction algorithms, the authors provide imaging time estimates for howX-ray nanoimaging can be scaled to macroscopic specimens. To arrive at this estimate, a phase contrast imaging model that includes plural scattering effects is used to calculate the required exposure and corresponding radiation dose. The coherent X-ray flux anticipated from upcoming diffraction-limited light sources is then considered. This imaging time estimation is in particular applied to the case of the connectomes of whole mouse brains. To image the connectome of the whole mouse brain, electron microscopy connectomics might require years, whereas optimized X-ray microscopy connectomics could reduce this to one week. Furthermore, this analysis points to challenges that need to be overcome (such as increased X-ray detector frame rate) and opportunities that advances in artificial-intelligence-based `smart' scanning might provide. While the technical advances required are daunting, it is shown that X-ray microscopy is indeed potentially applicable to nanoimaging of millimetre- or even centimetre-size specimens.

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Bayraktar, Sevi. "Choreographies of Dissent and the Politics of Public Space in State-of-Emergency Turkey". Performance Philosophy 5, nr 1 (30.11.2019): 90–108. http://dx.doi.org/10.21476/pp.2019.51269.

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This article investigates a recent period in which dissenting activism has been shifted in Istanbul under the state of emergency (2016-2018). Based on an ethnography conducted with activists in feminist and LGBTQI+ demonstrations, anti-emergency decree vigils, and the Presidential Referendum protests, the study discusses how activists resist and undermine mobilization of violence through using the hegemonic tools of repression tactically, and choreographically. By employing Hannah Arendt’s concepts of “politics” and “isolation,” I examine that state agencies like the police forcefully disperse protesters and display authority, oppression, and occupation of public spaces by constantly creating an atmosphere of fear and insecurity. In opposition, dissenters practice and rehearse dispersal as a resilient choreography to once again relate each other against the forces of isolation. I suggest the term “tactics of dispersal” to define and analyze how activists depart from the central assembly of the social movement to create smaller, mobile, and ephemeral assemblies. In the city-scale, by scattering themselves in the city of Istanbul and mobilizing peripheries of the urban space, dissenters re-choreograph and subvert a thanatopolitical strategy of dispersal in favor of pluralism under political hardship. In the bodily-scale, activists claim the public sphere through the transience of folk dance. Whenever protesters depart from folk dance collectives to create new ones, they perpetually re-configure the area and initiate novel actions contingent upon their temporal and positional assessments during the dance. Such tactical applications of dispersal characterized by the smaller scale and transitory gatherings with ever-changing combinations of bodies at the peripheral space of urban activism manifest its great potential for collective agency and plural politics.

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Scomoroscenco, Cristina, Mircea Teodorescu, Adina Raducan, Miruna Stan, Sorina Nicoleta Voicu, Bodgan Trica, Claudia Mihaela Ninciuleanu i in. "Novel Gel Microemulsion as Topical Drug Delivery System for Curcumin in Dermatocosmetics". Pharmaceutics 13, nr 4 (7.04.2021): 505. http://dx.doi.org/10.3390/pharmaceutics13040505.

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Gel microemulsion combines the advantages of the microemulsion, which can encapsulate, protect and deliver large quantities of active ingredients, and the gel, which is so appreciated in the cosmetic industry. This study aimed to develop and characterize new gel microemulsions suitable for topical cosmetic applications, using grape seed oil as the oily phase, which is often employed in pharmaceuticals, especially in cosmetics. The optimized microemulsion was formulated using Tween 80 and Plurol® Diisostearique CG as a surfactant mix and ethanol as a co-solvent. Three different water-soluble polymers were selected in order to increase the viscosity of the microemulsion: Carbopol® 980 NF, chitosan, and sodium hyaluronate salt. All used ingredients are safe, biocompatible and biodegradable. Curcumin was chosen as a model drug. The obtained systems were physico-chemically characterized by means of electrical conductivity, dynamic light scattering, polarized microscopy and rheometric measurements. Evaluation of the cytotoxicity was accomplished by MTT assay. In the final phase of the study, the release behavior of Curcumin from the optimized microemulsion and two gel microemulsions was evaluated. Additionally, mathematical models were applied to establish the kinetic release mechanism. The obtained gel microemulsions could be effective systems for incorporation and controlled release of the hydrophobic active ingredients.

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"Fourier deconvolution of electron energy-loss spectra". Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences 398, nr 1815 (9.04.1985): 395–404. http://dx.doi.org/10.1098/rspa.1985.0041.

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Electron energy-loss spectroscopy (e. e. l. s.) performed with an electron microscope can be used to obtain plasmon spectra, near-edge fine structure and extended electron energy-loss fine structure (ex. e. l. f. s.), as well as to do chemical analysis on truly microscopic samples. However, the very strength of the electron–electron interaction gives rise to significant and sometimes predominant plural scattering effects. To obtain consistent and reliable estimates of the single scattering distributions these effects must be accounted for. In this paper, two Fourier-transform deconvolution methods of removing plural scattering from electron energy-loss spectra and their implementation on a microcomputer, are discussed. Their relative advantages and limitations are considered together with examples of artefacts that may arise in both plasmon and core-loss spectra. As a result of deconvolution the sensitivity and accuracy of core-elemental analysis is enhanced but, more importantly, it is possible to obtain reproducible near-edge structure and plasmon spectra from relatively thick samples that would otherwise not be suitable for investigation by means of e. e. l. s.

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Buck, Edgar C., Brady D. Hanson, Judah I. Friese, Matt Douglas i Bruce K. McNamara. "Evidence for Neptunium Incorporation into Uranium (VI) Phases". MRS Proceedings 824 (2004). http://dx.doi.org/10.1557/proc-824-cc9.3.

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AbstractThis paper examines the ability of electron energy-loss spectroscopy (EELS) combined with transmission electron microscopy (TEM) to detect both low concentrations of Np in a U matrix and to provide evidence for incorporation of Np in U(VI) phases. The case for U(VI) secondary minerals acting as solubility-controlling phases for Np in repository performance assessment models has not been fully established. Direct evidence for incorporation, rather than sorption, continues to be difficult to obtain. Detection of Np with TEM-EELS is hampered by the occurrence of a plural (multiple) scattering event from the more abundant U atoms (U-M5 + U- O4,5), that results in severe overlap on the Np-M5 edge at ∼3665 eV. By examining the energy âgap' between the Np-M5 and Np-M4 edges (184 eV), a method for observing Np independently of the plural scattering event has been established. Clear evidence of Np incorporation into synthetic studtite {(UO2)(O2)(H2O)2](H2O)2} and uranophane {Ca(UO2)2(SiO3OH)2(H2O)5} has been found with TEM-EELS. The EELS technique continues to remain an important tool for examining the potential for transuranic behavior in nuclear waste materials.

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Rusz, Ján, Hans Lidbaum, Stefano Rubino, Björgvin Hjörvarsson, Peter M. Oppeneer, Olle Eriksson i Klaus Leifer. "Influence of plural scattering on the quantitative determination of spin and orbital moments in electron magnetic chiral dichroism measurements". Physical Review B 83, nr 13 (6.04.2011). http://dx.doi.org/10.1103/physrevb.83.132402.

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