bluuebunny/crossref_metadata_2025 huggingface dataset:
The prospects of a universal correction procedure for quantitative EPMA
Authors: Scott V. D. , Love G.
Published: August 2011

An overview is given of correction methods for quantitative electron probe microanalysis (EPMA). First, the physical basis of the technique is described; this includes a short treatment of earlier proposals to solve the problem. After pointing out the limitations of these methods, attention is focused on the more recent “curve‐fitting” approaches to derive correction formulae. It is concluded that several such methods are available which give very good results and that the original objective of producing a universal correction procedure for EPMA is now within grasp.
Energy‐dispersive x‐ray microprobe analysis of materials containing light elements using peak ratios
Authors: Hemens C. M. , Haythornthwaite R. F. , Nandi B. N.
Published: August 2011

Quantitative analyses of light elements using energy‐dispersive x‐ray microanalysis (EDX) is increasingly possible since the development of sealed light element ultra‐thin window detectors. However, the computer programs available for quantitative analyses fail for light elements because the correction and background modelling parameters are not accurately known. Therefore, we have developed a simple method of light element quantitative analysis using the peak ratios of two elements as the basis for calibration curves using stable standards. The use of peak ratios avoids the need for accurate ZAF corrections and minimizes many experimental variables. This article describes the criteria for the selection of standards, and the development of the calibration curve in the case of compounds containing oxygen and carbon. The success of the method depends on careful sample preparation and predetermined experimental parameters. The method has been successfully applied to the surface analysis of fresh and oxidized Western and Eastern Canadian coals.
Confocal laser‐scanned microscopy: Analog signal processing
Authors: Szarowski D. H. , Barnard D. P. , Smith K. L. , Swann J. W. , Holmes K. V. , Turner J. N.
Published: August 2011

Biological samples labelled with fluorescent markers often result in specimens with a dynamic range that is less than ideal for imaging with the confocal laser‐scanned microscope. This range can be either too great or too small, and thus prevents the entire image from being processed and/or displayed at the same time. The effect of analog signal processing to overcome this limitation was tested using a modified GW Electronics Image Enhancer in the image pipeline of a Bio‐Rad MRC‐500 Confocal Laser Scanning Microscope. The analog preprocessing did not interfere with subsequent digital processing. The use of homomorphic filtering allowed the dynamic range to be compressed. Fine structures with low signal levels were imaged with improved contrast while structures with high signal levels, did not saturate the detection and display systems. When the black levels were properly manipulated, the processor could be used to enhance signals that were near the noise level, in effect expanding the dynamic range. Both applications resulted in improved image quality and signal to noise. Other analog functions, notably logarithmic and exponentiation were also evaluated. Analog preprocessing produces images with better signal to noise than standard images after contrast stretching and background subtraction by off‐line digital processing. Since the analog processor functions in real time, image collection could be optimized directly, and subsequent digital processing further improved the images.
Imaging of intramembranous particles in frozen‐hydrated cells (Saccharomyces cerevisiae) by high resolution cryo SEM
Authors: Walther P. , Hentschel J. , Herter P. , Müller T. , Zierold K.
Published: August 2011

In order to investigate the potential of high‐resolution cryoscanning electron microscopy (SEM), frozen‐hydrated bulk specimens were compared with transmission electron microscopy (TEM) freeze‐fracture replicas. For this purpose a field emission SEM was equipped with a cryo unit consisting of a cold stage in the electron microscopical column and a dedicated cryo preparation chamber. Baker's yeast, Saccharomyces cerevisiae, was the chosen test specimen. The hexagonally arranged intramembranous particles of the plasmic fracture face of the plasmalemma are well known from TEM freeze‐fracture studies and can be clearly discerned from structures deriving from preparation artifacts. After freezing, fracturing, sputter‐coating with 3 nm of platinum, and vacuum transfer to the cold goniometer stage, the 16.5 nm periodic structure was resolved in the cryo‐SEM. Also, intramembranous particles in the nuclear envelope are preserved. Typical artifacts of cryo‐SEM are water vapour contaminations and mass loss due to electron irradiation of ice. However, these artifacts are easily recognized and discerned from biological information. Specific advantages of cryo‐SEM of frozen‐hydrated specimens are: (1) In comparison to SEM of dried material, dehydration artifacts such as shrinkage can be excluded. (2) Compared with freeze‐fracture replicas, larger specimens are obtained because no replica cleaning is necessary.
A study of polyethyleneterephthalate (PETP) films by colour cathodoluminescence in the SEM
Authors: Nazarov M. V. , Nazarova T. A. , Saparin G. V. , Obyden S. K. , Viskov M. V.
Published: August 2011

The local cathodoluminescence (CL) of polyethyleneterephthalate (PETP) films has been investigated by means of the SEM. We observed a change in both the intensity and the wavelength of CL depending on the charge injected. The observed changes in the CL spectra of PETP films are irreversible. This makes it possible to employ such films as carriers of information recorded by a fine electron beam with a density of 108 bit/cm2.
Characteristic fluorescence correction for layered samples part I: Closed solution for film‐substrate combination
Authors: Göhler K. , Hänisch M.
Published: August 2011

The main difficulty in solving the corresponding integral expressions for characteristic fluorescence of layered samples consists in the choice of an advantageous approximation of the depth distribution function ϕ (z). In accepting a point source, a linear dependence, or a sum of weighted exponential moments to describe primary excitation, a closed mathematical treatment of secondary excitation effects is possible. Part I of this series is restricted to the frequent case of film substrate samples. The contributing factors of fluorescence excitation are calculated assuming a sum of weighted exponential moments for primary depth distribution and using dimensionless variables. The influence of the shape of primary depth distribution is discussed and can be shown to be less than 5% for bulk conditions.
Conditions for voltage contrast observation over passivated devices
Authors: Kodama T. , Koyama N. , Uchikawa Y.
Published: August 2011

Inspection of passivated microdevices using the scanning electron microscope (SEM) at a low primary electron energy has been increasingly studied. Previously we reported an empirical formula for conditions under which SEM observations over the passivation layer can be made without inducing serious charging disturbances. An investigation of charge balance between primary and secondary electrons was presented. The present work investigates the charging disturbance‐free conditions of PSG, SiN, and Si3N4 passivated devices and how they are affected by beam irradiation. The storage time of the voltage contrast is measured for various values of primary electron energy and incident angle.
A method for generating morphometric data using SEM and an automated television image analysis system for the investigation of cell borders
Authors: Gusev S. A. , Baryshnikova N. A. , Pyatetsky A. A.
Published: August 2011

The traditional silver nitrate impregnation method used for visualization of cell borders does not allow the study of intercellular relationships and fails to demonstrate features of cell microrelief. It is shown that osmium tetroxide impregnation of vascular tissue, emphasizing cell border lines, and a special image analysis program for the semiautomatic system IBAS 2 can be used together for the effective analysis of the fine structure and of the cell layer. Our investigations of the aortic endothelium using this complex method have confirmed the heterogeneity of aortic endothelial cells in health and demonstrated that the endothelium of different aortic regions displays differential responses to blood pressure elevation and, further, that a major factor underlying the alterations observed in endothelial cells in disease and hypertension is the differential degree of overlap of the neighboring endothelial cells.
Detectors for low voltage scanning electron microscopy
Authors: Autrata R. , Hejna J.
Published: August 2011

Two simple electron detectors (low and high take‐off angles) for low‐voltage scanning electron microscopy were built and tested. They contain large area scintillators with an applied high voltage and are able to detect backscattered electrons with high efficiency. These detectors also can record the sum of backscattered and secondary electrons. The primary beam of the microscope is screened from the scintillator high voltage by grids, which also permit switching from the BSE to the (SE + BSE) mode. The circular symmetry of the grids minimizes the influence of applied potentials on the primary beam. The use of the low and high take‐off detectors permits the detection of back‐scattered electrons emitted from the specimen surface into different ranges of take‐off angles.
Transmission and double‐reflection scanning stage confocal microscope
Authors: Dixon A. E. , Damaskinos S. , Atkinson M. R.
Published: August 2011

A new confocal scanning‐stage transmit‐ted‐light and reflected‐light laser microscope is described. In addition to allowing confocal transmitted‐light imaging, this microscope has the unique feature of imaging both the top and bottom of a specimen in reflected light, with the two images in perfect registration. Only one detector is used; different imaging modes can be selected by simple rotation of the polarizers. Several confocal images are presented, chosen to illustrate the unique features of the instrument.
Quantitative electron probe microanalysis of nitrogen
Authors: Bastin G. F. , Heijligers H. J. M.
Published: August 2011

Quantitative electron probe microanalysis of nitrogen has been performed on 18 nitride specimens in the voltage range of 4–30 kV. A conventional lead stearate and a new W/Si multilayer analyzer crystal (2d = 5.98 nm) were used simultaneously. The net peak count rates on the latter crystal were approximately 2.8 times higher than on the lead stearate crystal. In addition, significant improvements in the peak to background ratios were achieved, which proved critical when dealing with difficult nitrides such as ZrN, Nb2N, and Mo2N. A most conspicuous feature of the new crystal, however, is its effective suppression of higher‐order reflections in the wavelength range of N‐Kα. As a result, backgrounds are free of interfering lines and spectral artifacts, which facilitates accurate background determination. Two procedures for the analysis of nitrogen in the presence of titanium are also discussed. One procedure is based on the assumption that the area–peak factor (APF, integral k‐ratio/peak k‐ratio) of the N‐Kα peak in Ti–N compounds relative to a nitrogen standard (Cr2N) has a fixed value which can be used in order to separate the Ti‐ll peak from the N‐Kα peak. Extensive tests on a number of compositions in the Ti–N system have shown that it is possible to do quantitative analysis of nitrogen in Ti–N compounds with a relative accuracy of better than 5%. For very low levels of nitrogen (below 15 at%) the APF method was found unsuitable. In such cases, however, the well‐known multiple least‐squares digital‐fitting techniques appeared to do an excellent job. In order to account for the effects of peak shape alterations in the N‐Kα peak, all nitrogen spectra were recorded in integral fashion and compared with those of the Cr2N standard. The shape alterations for the N‐Kα peak were much smaller than for B‐Kα and C‐Kα radiations: The observed values for the area–peak factor relative to Cr2N differed less than 5% from unity. The present work has resulted in a database containing 144 integral k‐ratios for N‐Kα and 149 peak k‐ratios for the x‐ray lines of the metal partners in the nitrides. Our own Gaussian ϕ(pz) matrix correction procedure “PROZA,” used in conjunction with a set of improved mass absorption coefficients, yielded excellent results for the nitrogen data: An average value of kcalc/Kmeas of 1.0051 and a relative root mean square deviation of 3.99%.
The use of charging effects in Al/Al2O3 metal‐matrix composites as a contrast mechanism in the SEM
Authors: Borchert A. M. , Vecchio K. S. , Stein R. D.
Published: August 2011

A technique is described to image two phases (alumina and spinel) within a metal‐matrix composite which takes advantage of charging effects that occur during examination in an SEM. Microscope and specimen parameters which affect the amount of contrast generated via charging are discussed, and imaging strategies are introduced to optimize the effect. “Model” metal‐matrix composite specimens were developed to verify the degree of charging in each phase.
3D characterization of the eutectic Au–Si alloy by using a nuclear microprobe
Authors: Demortier G. , Mathot S.
Published: August 2011

The quantitative analysis of silicon in gold is performed in the three dimensions by the spectroscopy of protons produced in various depths by scanning a microbeam of energetic deuterons. Owing to the high Coulomb repulsion of incident deuterons by heavy nuclei (like gold), proton emission can only be induced on light elements. The incident deuterons may approach silicon nuclei at a sufficiently close distance to be broken and to give rise to an emission of energetic protons. Measuring the energy of these protons leads to a quantitative method of analysis of silicon at various depths under the surface of the irradiated material. The spatial resolution in the three dimensions of space lies around 3 microns. Application is made to the study of eutectic gold‐silicon alloys formed, in situ, and used for the soldering of gold at a low temperature (400° C).
In vivo imaging of human teeth and skin using real‐time confocal microscopy
Authors: New K. C. , Petroll W. M. , Boyde A. , Martin L. , Corcuff P. , Leveque J. L. , Lemp M. A. , Cavanagh H. D. , Jester J. V.
Published: August 2011

Confocal microscopy is currently being used to obtain images with higher lateral and axial resolution than conventional light microscopic techniques. Most current confocal microscopic applications describe the use of in vitro preparations. The tandem scanning microscope (TSM) can be applied in the in vivo microscopic evaluation of living tissue. This article discusses in vivo applications of the TSM in the study of human teeth and skin.
Characterization of chevron‐shaped permalloy magnetic memory elements by four magnetic imaging techniques
Authors: Cameron G. P. , Eberle W. J.
Published: August 2011

Scanning auger microscopy (SAM) and the recently developed scanning electron microscopy with polarization analysis (SEMPA) are easily combined analytical techniques which provide quantitative submicrometer images of X‐, Y‐, and Z‐axis spin polarization components of magnetization. SAM/SEMPA, along with three established magnetic imaging techniques (Bitter colloidal, longitudinal magneto‐optic Kerr microscopy, and the Fresnel mode of Lorentz microscopy), was used to characterize a chevron‐shaped permalloy magnetic memory element. Reflected light and secondary electrons were used to image the topography. Auger electrons identified and imaged the elemental composition. Reflected light, transmitted electrons, and secondary electrons were used to image the magnetic microstructure. The Bitter colloidal images showed only the delineation of the domain walls, and the longitudinal magneto‐optic Kerr microscopy images produced similar results. The Lorentz microscopy images provided the most qualitative magnetization information. SAM/SEMPA was the only technique to combine elemental information and quantitative magnetization information with images having submicrometer resolution.
New confocal LM method for studying local relative microrelief with special reference to wear studies
Authors: Boyde A. , Fortelius M.
Published: August 2011

Subtracting a smoothed version of a digital map image from the unprocessed original leaves a map of the local surface relief. The map in question is obtained by through focussing with a confocal reflection microscope, retaining the focus value for the greatest signal level at each X,Y pixel address as the Z (height/depth) coordinate.
New growth features of natural diamonds, revealed by color cathodoluminescence scanning electron microscope (CCL SEM) technique
Authors: Zezin R. B. , Smirnova E. P. , Saparin G. V. , Obyden S. K.
Published: August 2011

The internal structure of diamonds with various habit was studied by color cathodoluminescence scanning electron microscopy (CCL SEM). A new growth mechanism was ascertained for diamonds of rounded and octahedral habit. The specific growth details found by means of CCL SEM testify to the fact that the crystallization of diamonds proceeded from the specimen periphery toward the centre by formation of agate secretions. CCL determined was the structure of transparent cubic crystals to be a combination of zones with cuboid surfaces and fibrous structure. The authors consider that both cuboid and fibrous structures are the result of normal (nontangential) growth mechanisms which may be realized during secretional filling of the space, determined for a number of crystals of rounded and octahedral habitus.
Reactive ion etching of GaAs with SiCl4: A residual damage and electrical investigation
Authors: Cole M. W. , Salimian S. , Cooper C. B. , Lee H. S. , Dutta M.
Published: August 2011

The residual damage incurred by various SiCl4 reactive ion etching (RIE) conditions was investigated by transmission electron microscopy (TEM), Raman spectroscopy, ion channeling, and electrical characterization methods. Lattice damage to depths greater than 100 nm was incurred in all of the RIE processing situations. The lowest power density, longest etch time RIE exhibited the lowest defect density, roughest surface morphology, and poorest quality GaAs regrowth. The highest power density, shortest etch time RIE displayed the highest defect density, smoothest surface morphology, and highest quality GaAs regrowth. The electrical measurements, Schottky diode characteristics, degraded with decreasing power density and increasing etch times. Overall, the characterization results suggest that the high power density, shortest etch time sample possesses the most desirable properties for device fabrication requirements.
Quantitative x‐ray microanalysis of spherical inclusions embedded in a matrix using a SEM and Monte Carlo simulations
Authors: Gauvin Raynald , L'Espérance Gilles , St‐Laurent Sylvain
Published: August 2011

The current schemes of quantification of x‐ray microanalysis in the SEM [ZAF and σ(ρZ) methods] are valid for specimens of homogeneous composition. The determination of the chemical composition of small inclusions using these techniques is impossible because the volume of x‐ray emission is not of homogeneous composition. A scheme of quantification to determine the composition of small inclusions embedded in a matrix has been developed using Monte Carlo simulations. This scheme is similar to that developed by Kyser and Murata (1974) for the quantification of thin foils deposited on a substrate using x‐ray microanalysis in the SEM.
In situ topography measurement in the SEM
Authors: Thong J. T. L. , Breton B. C.
Published: August 2011

An automatic technique for measuring heights in situ in the SEM based on a combination of stereo‐metric and focusing methods has been developed. A pair of images of a surface element on the specimen is obtained by tilting the beam electrically in a manner such that the plane containing the tilt axis is coincident with the focal plane of the final lens. Cross‐correlation is used to determine the parallax between the image pair which is then used to iteratively correct the height of the tilt axis by changing the lens focus. As a result, the lens focus tracks the specimen topography. With an appropriate specimen surface containing high resolution features for image correlation, the technique is capable of maintaining both its lateral and vertical resolutions over several decades of height displacement up to 100 μm. In an experimental system based on a commercial electron‐optical column, spot, line profile, and three‐dimensional measurements have been demonstrated.
Optimized reflection imaging in laser confocal microscopy and its application to neurobiology: Modificationsa to the biorad MRC‐500
Authors: Szarowski D. H. , Smith K. L. , Herchenroder A. , Matuszek G. , Swann J. W. , Turner J. N.
Published: August 2011

Reflection images of biological specimens recorded using laser‐scanned confocal microscopes are frequently degraded by low image contrast, poor signal to noise, and the inability to image deeper in the specimen than 10–20 μm. Artifactual internal reflections often are a source of these limitations, but they can be reduced or eliminated by the use of polarization components. Designs for the incorporation and optimum use of these components in the BioRad MRC‐500 are presented. The effect of the internal reflections was reduced by optimum rotational alignment of both a quarterwave plate and an analyzer. Absorption of incident and reflected light by both the stained cells and the background tissue of the specimen also seriously degrades image signal to noise, and is a function of specimen preparation and the wavelength of light used. The red line of a helium‐neon laser was not as readily absorbed as the blue and green lines of an argon‐ion laser when imaging neurobiological specimens contrasted with either peroxidase/diaminobenzidine or Golgi staining. Specimens many times thicker were imaged with red laser light and with superior image quality compared with blue or green laser light.
An efficient single crystal BSE detector in SEM
Authors: Autrata R. , Hermann R. , Müller M.
Published: August 2011

Using the optical modifications described, the signal of the wide‐angle BSE detector can be increased 3.7‐fold compared with the detector type illustrated in Figure 1. The increase was achieved by more fully exploiting the optical phenomena of diffusion, reflection at the critical angle and antireflection, and especially that of their combined effects. A higher photon energy transfer was obtained by specific optical modifications to the scintillator and the light guide. Based on the current modifications, it can be estimated that about 75% of the generated light reaches the PMT. It is necessary, therefore, to revise all values previously published of the DQE coefficient of the YAG scintillator. A general value of DQE is of very limited use depending as it does on the specific conditions under which light emerges from the YAG scintillator. The DQE, therefore, does not permit sufficiently accurate comparison with other scintillation materials. The DQE can be evaluated only for a completed detector configuration in which the laws of geometrical optics apply, or it can be used for making comparisons of scintillation materials used in the same detector configuration.
Chromatism and confocality in confocal microscopes
Authors: Akinyemi O. , Boyde A. , Browne M. A. , Hadravsky M. , Petran M.
Published: August 2011

In confocal microscopes, whenever a broadband light source is used, or when excitation and detection are performed at different wavelengths, for example in fluorescence, then the influence of microscope objective chromatism on the degree of confocality is very important. With poorly corrected objectives, depth of field will be increased and in the case of fluorescence the image may be lost altogether. Presented here are observations with truly achromatic reflecting objectives and with the same objectives modified by introduction of a known amount of chromatic aberration. The results should encourage manufacturers to consider development and production of both reflecting microscope objectives and refractive lenses with more carefully designed/controlled chromatic aberration.
Fluorescence lifetime imaging using a confocal laser scanning microscope
Authors: Buurman E. P. , Sanders R. , Draaijer A. , Gerritsen H. C. , van Veen J. J. F. , Houpt P. M. , Levine Y. K.
Published: August 2011

The implementation of a fast fluorescence life‐time imaging method in a confocal laser scanning microscope is described. The set up utilizes a low‐power continuous wave (CW) argon ion laser equipped with an electro‐optic chopper producing nanosecond pulses with a repetition rate up to 25 MHz. A time‐gated detection technique enables the measurement of the lifetime of a pixel in 40 μs. The first confocal fluorescence lifetime contrast images are presented. Application of fluorescence lifetime imaging in multilabelling experiments for discrimination between different labels with overlapping emission bands, for probing the local environment of a fluorescent molecule, and for quantitative fluorescence are discussed.
Microsecond duration pressure pulse generator for in situ dynamically loaded SEM fracture studies
Authors: Fishbine B. H. , Macy R. J.
Published: August 2011

We describe a technique to impulse load small cylindrical specimens for in situ, real‐time SEM studies of dynamically loaded fracture. Loading is done magnetically with a solenoidal coil of 10 mm length and 1 mm radius. The entire loading assembly fits on the SEM stage; there is no need for shock‐isolated bellows apparatus. The only vacuum feedthrough required is an MHV coaxial bulkhead connection. A ballistic pendulum measurement gave a peak compressive pressure of ∼20 MPa, with a pressure pulse width of 1.33 μs. Pressures > 80 MPa can easily be generated. Using this device we have obtained real‐time SEM movies of dynamically loaded fracture of rosin.
Acquisition and processing of scanning electron microscope images using a PC and a framestore
Authors: McClean J. A. , Dhariwal R. S. , Milne N. G.
Published: August 2011

A versatile, low‐cost data acquisition and processing system for scanning electron microscope (SEM) images has been successfully developed and demonstrated. This is based on an Amstrad PC and a framestore interfaced to the SEM, and is an upgrade of an earlier BBC microbased system. In addition to supporting colour x‐ray mapping, as reported previously, the PC‐based unit incorporates new features which enhance the system's performance, flexibility, and overall user friendliness. An example of the system's capabilities in a very large‐scale integrated circuit application is presented. This relates to the processing and analysis of a series of images taken on the surface of a Motorola MC 68000 microprocessor, with and without a voltage stimulus.
Point spread function of the general cone‐beam x‐ray reconstruction formula
Authors: Wang G. , Lin T. H. , Cheng P. C. , Shinozaki D. M.
Published: August 2011

In this paper, the spatially varying point spread function (PSF) of the general cone‐beam x‐ray reconstruction formula is derived. It is proved that the vertical integral of the PSF is a two‐dimensional δ function. Therefore, although the general cone‐beam formula is not exact in nature, the vertical integral of the reconstructed three‐dimensional image is equal to that of the actual image. The band‐limited version of the PSF is also derived. The PSF of the general cone‐beam formula is simulated, based on which the reconstruction resolution can be approximately inferred.
Space heterogeneity of luminescent centers in SiC‐epitaxial layers detected by the color CL‐SEM
Authors: Saparin G. V. , Mokhov E. N. , Obyden S. K. , Chukichev M. V. , Roenkov A. D. , Ivanov A. I.
Published: August 2011

The spatial distribution of luminescence centers in SiC epitaxial layers grown by the sublimation “sandwich method” have been studied by means of the real‐colour SEM technique. The cellular inhomogeneity distribution of cathodoluminescence (CL) intensity in epitaxial layers is demonstrated. Different spectral composition of CL emission depending upon the growth temperature is observed near p‐n junctions and along the substrate boundary. The nature of the inhomogeneities in SiC epitaxial layers is discussed.
Identification and study of the same cell in monolayer culture by different methods of light microscopy, scanning, and transmission electron microscopy. Application for cryodamaged cells examination
Authors: Katsen A. D. , Tregubova N. A. , Andrushkevich V. V. , Rovensky Yu. A.
Published: August 2011

Cells were cultivated on transparent conductive substrates, glass slides coated with indium oxide; individual cells were marked with a diamond indentor. Cell cultures were frozen (–15°C), thawed, and then stained with fluorescent dyes to determine cell damage. The marked cells were examined by phase contrast, fluorescence, and Nomarski DIC microscopy. After aldehyde and osmium tetroxide fixation, the cell preparations were sequentially treated with tannic acid, uranyl acetate, and lead citrate. The same marked cell could be sequentially studied by light microscopy (LM; in water immersion conditions), scanning electron microscopy (SEM; after dehydration and critical point drying), and transmission electron microscopy (TEM; after embedding of cell samples in epoxy resin and laser marking of the cell previously marked with a diamond indentor). The method used ensures good preservation of cell morphology, cell surface relief, and intracellular structures. The treatment used renders the cells conductive and permitted SEM of uncoated culture cells on conductive substrates.
Cryoscanning electron microscopy of microbial extracellular polysaccharides and their association with minerals
Authors: Chenu C. , Jaunet A. M.
Published: August 2011

The morphology of pure microbial extracellular polysaccharides (EPS) and of their association with a mineral was studied by scanning electron microscopy. Several methods were compared: cryo‐SEM, critical point dehydration (CPD), and TEM observation after solvent exchanges and inclusion in a resin. The EPS were observed as fibrils, interconnected into a network. Their dimensions were compared with literature data on the conformation and shape of the given EPS. It was deduced that these EPS have an undoubtably fibrillar structure when hydrated, and that some aggregation or collapse artifacts took place in both CPD or cryo‐SEM samples but were quite limited. Cryo‐SEM appears then as a relevant tool for the study of the secretion of EPS by microorganisms in soils.
Deconvolution of scanning electron microscopy images
Authors: Yano Fumiko , Nomura Setsuo
Published: August 2011

This paper describes a method of removing blurs in scanning electron microscopy (SEM) images caused by the existence of a finite beam size. Although the resolution of electron microscopy images has been dramatically improved by the use of high‐brightness electron guns and low‐aberration electron lenses, it is still limited by lens aberration and electron diffraction. Both are inevitable in practical electron optics. Therefore, a further reduction in resolution by improving SEM hardware seems difficult. In order to overcome this difficulty, computer deconvolution has been proposed for SEM images. In the present work, the SEM image is deconvoluted using the electron beam profile estimated from beam optics calculation. The results show that the resolution of the deconvoluted image is improved to one half of the resolution of the original SEM image.
Comparison of ion beam sputtered chromium and iridium films for electron microscopy applications
Authors: Cardinale G. F. , Carlino V. L. , Howitt D. G.
Published: August 2011

The structure and composition of thin, conductive metallic films of chromium and iridium that are typical of the coatings used for electron microscopy is described. The purpose of this study was to determine the grain size and composition of the films deposited, with thicknesses of 1 nm, 2.5 nm, and 5 nm, onto amorphous carbon films using ion beam sputtering with argon as the sputtering gas. A comparison between chromium films deposited under conditions of liquid nitrogen (LN) trapping or of no trapping revealed slight differences in their microstructure. As expected, the grain size of the films increased with the thickness, and the average grain sizes varied between 10 and 25 nm. Grain size was also found to depend on the source of ion beam energy; the correlation between grain size and beam energy was more pronounced in the iridium films than in the chromium films. This effect was greater when the deposition chamber was not LN trapped. As the ion beam energy increased from 18 W to 24 W, there was a corresponding increase in grain size in some of the films. Although transmission electron diffraction analysis indicated the presence of about 5% chromium oxide in the chromium films, no oxide was detected in the iridium films.
Possibilities of modulated cathodoluminescence for multilayer structure characterization
Authors: Kireev V. A. , Razgonov I. I. , Yakimov E. B.
Published: August 2011

The basic principles of modulated cathodoluminescence (MCL) are discussed herein, and the possibilities of the technique are demonstrated, using computer simulation of the MCL signal in a framework of simplified assumptions. Extension of the dependences obtained for less specific cases are discussed. The procedures for separation of the CL spectra associated with the different layers of two‐ and three‐layer structures are also described.
Low‐temperature scanning electron microscopy in fungus‐nematode interaction
Authors: Den Belder E. , Boekestein A. , Van Esch J. W. J. , Thiel F.
Published: August 2011

A comparative study has been made of different preparation techniques used for the scanning electron microscope (SEM), with regard to their application to fungus‐nematode interaction. The preparation of frozen‐hydrated specimens of both healthy and Arthrobotrys‐oli‐gospora‐infected second‐stage larvae of the root‐knot nematode (Meloidogyne sp.) is described, and the results are compared with those obtained by critical point‐drying and freeze‐drying. In all cases the frozen‐hydrated specimens consistently showed the best preservation.
Video‐rate confocal reflection microscopy of neoplastic cells: Rate of intracellular movement and peripheral motility characteristic of neoplastic cell line (RSK4) with high degree of growth independence in vitro
Authors: Vesely P. , Jones S. J. , Boyde A.
Published: August 2011

Video‐rate laser confocal interference reflection microscopy was used to demonstrate rapid motion of intracellular organelles and features at the cell periphery in a fully transformed neoplastic cell line, RSK4, and in four other neoplastic cell populations. In the RSK4 cells, vibrational and trafficking movements of intracellular particles at a rate greater than 25 Hz and ranging down to 5 Hz were recorded. Rapidly moving processes changed to ruffles, then microspikes, and previously undetectable ephemeral intercellular contacts were seen. Dynamic cyclical changes were revealed in the sizes of the podosomal close contacts of the transformed cells. The visibility of such features and the temporal and spatial resolution are improved over earlier methods. The fact that fast cellular and intracellular movements can be detected with this microscopic technique offers new possibilities in attempting to recognise differences between unimpaired living cells, and it may prove useful in the identification of malignant cells.
Imaging and colour coding of magnetic domains by kerr scanning optical microscopy
Authors: Büscher P. , Reimer L.
Published: August 2011

The imaging of ferromagnetic domains by the transverse Kerr effect using a scanning optical microscope (SOM) with two or four directions of light incidence (± x, ± y) allows the digital record of the By and Bx components of the magnetic induction B. These components can be used to calculate a two‐dimensional colour‐coded map of B, which can be superposed by vector arrows.
Application of confocal laser scanning microscopy to analysis of H2O2‐induced DNA damage in human cells
Authors: Fairbairn Daryl , O'Neill Kim L. , Standing Michael D.
Published: August 2011

Confocal laser scanning microscopy (CLSM) offers improved depth discrimination and spatial resolution to the analysis of biologic samples. We demonstrate in this paper that such technology is valuable in examining DNA single‐strand breaks in human cells. The single‐cell‐gel (SCG) assay is a new technique for measuring DNA strand breaks in individual cells. Cells embedded in lowmelting‐point agarose are treated with varying concentrations of hydrogen peroxide to induce DNA strand breaks. Following cell lysis and alkaline electrophoresis, which enables single‐stranded break detection, analysis of the resulting “comets” provides an accurate method of comparing changes in DNA migration patterns, which have been shown to reflect the DNA damage levels. A statistically significant difference (p < 0.01) in single‐stranded DNA damage levels was detected in cells exposed to hydrogen peroxide concentrations as low as 10 nm for 2 min. LSM analysis of the SCG technique allows rapid, sensitive and reproducible quantitation of single‐stranded breaks of cellular DNA.
A formula to compute total elastic mott cross‐sections
Authors: Gauvin Raynald , Drouin Dominique
Published: August 2011

A formula to compute total elastic Mott cross‐sections as well as a tabulation of the constants to compute total Mott cross‐sections for 94 elements are presented herein. This formula and the constants have been obtained from the values of total elastic Mott cross‐sections computed by Czyżewski et al. (1990) using Thomas‐Fermi‐Dirac atomic potentials for atomic numbers greater than 54 and Hartree‐fock potentials for atomic numbers less than 55. Also, a Monte Carlo program simulating the trajectories of electrons in bulk specimens using our formula of total elastic Mott cross‐sections and the single scattering approach is discussed. Values of backscattering coefficients in energy functions for C, Al, Cu, Ag, and Au computed by this program and by other Monte Carlo programs are compared with values measured experimentally by several researchers.
Low‐temperature SEM studies of beam‐induced voltage contrast in YBCO thin films
Authors: Hollin C. A. , Hall Y G. , Hulbert J. K. , Zarucki P. N. , Sutton S. D. , Abell J. S.
Published: August 2011

Beam‐induced voltage contrast has been demonstrated in a superconducting thin film of YBa2Cu3O7‐x (YBCO) grown on MgO. Copper‐rich inclusions in the material contribute to spatially varying resistive behaviour but do not account for all the observed details. A new method of scanning in which the beam was moved away from the sample between each data acquisition point was found to increase the resolution by limiting thermalisation, to allow imaging of resistive features as small as 0.5 μm. Direct comparisons of beam‐induced contrast and micro‐structure at 9000 times magnification were possible using simultaneous image acquisition via a purpose‐built image store. Mounting a preamplifier within the scanning electron microscope chamber, to give a variable overall gain of 1000–100,000, was also found to significantly improve the signal‐to‐noise ratio.
A comparative materials study of magnetron ion etched GaAs using Freon‐12, SiCl4 and BCl3
Authors: Cole M. W. , McLane G. F. , Eckart D. W. , Meyyappan M.
Published: August 2011

Etch characteristics and residual damage incurred via magnetron ion etching of GaAs using three different etch gases, namely, freon‐12, SiCl4 and BCl3, at two different power levels has been studied. Transmission electron microscopy, scanning electron microscopy, Auger electron spectroscopy, and Schottky diode measurements were employed to determine the suitability of the processed surfaces for device fabrication. Lattice damage was incurred in all processing situations in the form of small dislocation loops. Samples etched in freon‐12 at the highest power density exhibited the roughest surface morphology, while those etched in SiCl4 and BCl3 resulted in planar surfaces. The Schottky barrier diode characteristics, for all etch gases, degraded with increasing power density. The electrical quality of the BCl3‐etched GaAs at the lowest power density was superior to that of the other etch gases at all power levels. The etched profiles of SiCl4 and BCl3 yielded vertical sidewalls, whereas freon‐12 yielded a negative undercut. The BCl3‐etched GaAs surfaces were residue‐free, while those of freon‐12 and SiCl4 exhibited surface or sidewall contamination. Our results have demonstrated that magnetron ion etching with BCl3 yields planar residue‐free surfaces with minimum material surface damage and superior electrical integrity compared with GaAs etched with freon‐12 or SiCl4.
A simple backscattered electrons and specimen current detection device for the scanning electron microscope
Authors: Viturro H. , Peez C. , Bonetto R. D. , Alvarez A. G.
Published: August 2011

A simple, low‐investment device has been developed that allows the collection of backscattered electrons (BSEs) and specimen current (SC) signals for imaging purposes and current measurement. Originally, this system was designed for detection, measurement, and display of specimen current, with a video signal output whose level was modulated by this current. Eventually, a BSE detector was developed, using a graphite disk (about 8 cm in diameter) to collect the BSEs. The disk was mounted on a Philips SEM 5O5, attached and concentrically to the final lens aperture. This configuration gives a large solid angle of collection. The collected charge is further processed by the same electronics used in the aforementioned SC detection system. Electron channeling, topographic contrast with BSE, and material contrast with BSE and SC images can be obtained with reasonably good edge definition.
Applications of SFM in the chemical industry
Authors: Anders M. , Fuchs H.
Published: August 2011

Scanning force microscopy techniques were applied to investigate the surface of magnetic tapes and organic surfaces such as film forming and radiation‐sensitive polymeric materials. The unique potential of the method to derive quantitative data, that is, surface roughness and asymmetry parameters, is demonstrated. Force‐modulation experiments indicate that liquid/gas interfaces can be directly detected.
Applications of scanning probe microscopies in technology and manufacturing
Authors: Persch G. , Born Ch. , Engelmann H. , Koehler K. , Utesch B.
Published: August 2011

Within the last 10 years the scanning probe microscopies (SPMs) have been applied to a variety of problems with the main emphasis on scientific applications. The SPM techniques have to date also found their technical applications. The simple concept can easily be adapted to a variety of different applications in high technologic manufacturing processes. The scanning tunneling microscope is now considered as a standard measuring equipment, in the meantime there exists a whole family of SPMs with promising applications in not only a pure scientific environment but also in a manufacturing environment. As examples for industrial applications, we report on magnetic force microscopic investigations, on magnetic storage device components, and on a relatively new technique for nanohardness investigations of thin‐films by an atomic force microscope.
Topography and performance of gas‐sensing devices: An AFM study
Authors: Hacker Birgitta , Fleischer Maximilian , Meixner Hans
Published: August 2011

The topography of resistive Ga2O3 metal oxide sensing devices was examined and characterized with an atomic force microscope (AFM). The sensing devices do not have to be destroyed for characterization and stay fully functional. Deposition of nobel metal dispersions, for example, palladium (Pd), onto the sensor surface improves its properties by adding catalytic activity. The distribution of the Pd clusters was investigated.
Two classes of defect recombination behaviour in silicon as studied by SEM‐EBIC
Authors: Kittler M. , Seifert W.
Published: August 2011

Electron‐beam‐induced current investigations using variation of temperature and beam current are applied to study NiSi2 particles and 60° misfit dislocations. The recombination activity of NiSi2 particles increases with temperature and has a beam‐current dependence influenced by the doping level, with negative slope for low doping. Usually, the misfit dislocations increase their activity upon sample cooling, but in few cases the opposite behaviour was found as well. The results are discussed in terms of two classes of recombination activity controlled by defect charging/deep levels or by shallow centres.
Application of current‐scanning deep level transient spectroscopy to deformed silicon crystals—first results
Authors: Kreis J. , Alexander H.
Published: August 2011

We have developed a scanning deep level transient spectrometer (SDLTS), using the current‐detection principle. With this spectrometer it is possible to detect deep levels in the band gap with a spatial resolution of several μm. From electron‐beam‐induced DLTS spectra of plastically deformed n‐type silicon crystals, one can conclude that under the chosen experimental conditions only minority carrier traps contribute to the SDLTS signal.
Option prices and pricing theory: combining financial mathematics with statistical modeling
Authors: Chen Ling , Lai Tze Leung , Lim Tiong Wee
Published: August 2011

After an overview of important developments of option pricing theory, this article describes statistical approaches to modeling the difference between the theoretical and actual prices. An empirical study is given to compare various approaches. WIREs Comp Stat 2011 3 566–576 DOI: 10.1002/wics.186

This article is categorized under:

Applications of Computational Statistics > Computational Finance
Factorial designs
Authors: Dey Aloke
Published: August 2011

In many scientific investigations, interest lies in studying the effects of several input variables simultaneously on an output variable. Factorial experiments are ideally suited for such investigations. The importance of factorial experiments stems from the fact that such experiments allow the estimation of individual effects of the input variables as also their inter‐dependence at the same time, thus providing a basis for drawing inference over a wide range of conditions. Some basic ideas of factorial experiments and issues related to the designing of such experiments are discussed with emphasis on symmetric 2‐ and 3‐level experiments. WIREs Comp Stat 2011 3 577–581 DOI: 10.1002/wics.191

This article is categorized under:

Statistical Models > Classification Models
On a Realistic Growth Mechanism for Quasicrystals
Authors: Steurer Walter
Published: August 2011

Simple rules are discussed that can guide under realistic conditions the growth of quasicrystals. We propose a two‐step mechanism where the well‐known overlap rules for the fundamental atomic clusters are complemented by the new layer‐continuation rule. This rule demands that the sets of atomic layers, crisscrossing each atomic cluster according to its eigensymmetry, have to be continued across all other clusters formed during the growth process. On one hand, this combined growth rule is local because each fundamental cluster already defines the overlap rules as well as the basic set of atomic layers. On the other hand, it is global because the framework of atomic layers originating locally from each cluster extends infinitely. The layer‐continuation rule guides the attachment of atoms to the growing quasicrystal and assists the overlap rules, which are at the high temperatures, where crystal growth takes place, only weakly supported by specific atomic arrangements in the shared cluster volumes.