bluuebunny/crossref_metadata_2025_split huggingface dataset:
Observation of current‐density filamentation in multilayer structures by EBIC measurements
Authors: Wierschem A. , Niedernostheide F.‐J. , Gorbatyuk A. , Purwins H.‐G. 
Published: June 2010

AbstractThe total current‐voltage characteristics of the p+‐n+‐p‐n− and n+‐p‐n‐p− diodes under investigation show branches of negative differential resistance. Accompanied by the appearance of negative differential resistance is a filamentation of current‐density and electric‐field distribution. Electron beam‐induced current (EBIC) measurements were used to examine the properties of filamentation from the point of view of self‐organized pattern formation. Besides the detection of the spatial distribution of the electric field, EBIC measurements give information on current‐density filamentation. Furthermore, the perturbation by the electron beam gives information on the dynamic behavior of the filamentary structure.
Monitoring the performance of energy dispersive spectrometer detectors at low energy
Authors: Hovington Pierre , L'Espérance Gilles , Baril Eric , Rigaud Michel 
Published: June 2010

AbstractThe performance of the energy dispersive spectrometer (EDS) detectors has to be established in its original state and monitored periodically to ensure the stability and long‐term performance of the system. Because EDS detectors are cooled by liquid nitrogen and because the environment is not an ultra‐high vacuum, ice and contaminants will buld up in front of the detector crystal, decreasing the detection efficiency at low energy. Few performance tests are suitable for the specifics problems found at low energy. The proposed test is based on a new procedure for the modelling of the decrease of detection efficiency (DODE) with time (Hovington et al. 1993). It was found that the deposition rate of both ice and carbon increased significantly when porous uncoated samples were observed. Significant difference between spectra acquired immediately after different conditioning was also found. The proposed procedure can be used to determine the optimum time before a conditioning cycle, to detect an abnormal accumulation of contaminant both in front of the detector and at the sample surface, and to diagnose a broken window and a malfunction in the conditioning apparatus.
How to analyze high‐aspect ratio pits with the coaxial scanning auger microprobe
Authors: Kibalov D. S. , Smirnov V. K. 
Published: June 2010

AbstractA new technique has solved the problem of Auger analysis of high‐aspect ratio pits. The nondestructive analysis of these micron‐size pits is important for the development of gigabit memory chips. Very suitable for the analysis is the coaxial scanning Auger microprobe (SAM), the electron gun of which is coaxial with the cylindrical‐mirror analyzer (CMA). However, this SAM could not probe the bottom of a high‐aspect ratio pit because the Auger signal is trapped in the pit. The solution to the problem was the use of an electrostatic deflector attached to the sample mount in front of the CMA. Theory and experiments proved the advantage of this technique.
Scanning force microscopy of chromatin fibers in air and in liquid
Authors: Fritzsche W. , Schaper A. , Jovin T. M. 
Published: June 2010

AbstractWe have adapted specimen preparation techniques of conventional electron microscopy for visualizing chromatin structures in the scanning force microscope (SFM) in air and in liquid. The beaded substructure of the nucleoprotein filament was obtained after hypotonic lysis of chicken erythrocytes and air drying, whereas supranucleosomal structures were preserved after treatment of cell nuclei with detergent. In the latter case, the nucleosomes were still distinct but appeared more condensed. A modified droplet diffusion‐spreading technique of chromatin from Namalwa cells (a human B‐lymphoid line) yielded a uniform filamentous morphology and similar fiber appearance. A reversible swelling of spread chromatin was observed upon exposure of air‐dried samples to solutions differing in salt concentrations.
An optical spectrometer for a confocal scanning laser microscope
Authors: Trepte Oliver 
Published: June 2010

AbstractAn optical spectrometer for the visible range has been developed for the confocal scanning laser microscope (CSLM) Phoibos 1000. The spectrometer records information from a single point or a user‐defined region within the microscope specimen. A prism disperses the spectral components of the recorded light over a linear CCD photodiode array with 256 elements. A regulated cooling unit cools the diode array, thereby reducing the detector dark current to a level, which allows integration times of up to 60 s. The spectral resolving power, λ/Δλ, ranges from 400 at λ = 375 nm to 100 at λ = 700 nm. Since the entrance aperture of the spectrometer has the same diameter as the detector aperture of the CSLM, the three‐dimensional spatial resolution for spectrometer readings is equivalent to that of conventional confocal scanning, that is, down to 0.2 μm lateral and 0.8 μm axial resolution with an N.A.=1.3 objective.
Determination of ZrO2 distribution in an Al2O3 matrix by digital image analysis and point‐pattern analysis
Authors: Samardžija Z. , Kunaver U. , Novak M. Čeh S. 
Published: June 2010

AbstractDigital image analysis and point‐pattern analysis were applied to the microstructures of Al2O3‐ZrO2 composites in order to evaluate and classify the distribution of ZrO2 particles. Scanning electron microscopy micrographs of Al2O3‐ZrO2 microstructures were digitized and processed into binary images. Point‐pattern analysis was performed using data for mass centers for each ZrO2 particle and the calculated distribution functions were compared with defined point‐pattern distributions—clustered, random, and ordered. Distribution functions for analyzed samples were classified into random groups with different degrees of homogeneity, arising due to the preparation routine. It was shown that the point‐pattern analysis can be used to distinguish between the type of distribution and degree of homogeneity for Al2O3 ceramic composites.
Quantification of spherical inclusions in the scanning electron microscope using Monte Carlo simulations
Authors: Gauvin Raynald , Hovington Pierre , Drouin Dominique 
Published: June 2010

AbstractQuantitative x‐ray analysis of spherical inclusions embedded in a matrix is not possible using the classical ZAF and ϕ(ρ)Z methods based on specimens of homogeneous composition. Gauvin et al. (1992) have demonstrated that Monte Carlo simulations can be used to perform quantitative analysis of spherical inclusions of homogeneous composition. In this paper, this method is extended to obtain an analytical expression to perform such quantification. Also, Monte Carlo simulations are used to simulate x‐ray and electron backscattering images of spherical inclusions in order to improve our understanding of contrast mechanism.
Error analysis on a generalized Feldkamp's cone‐beam computed tomography algorithm
Authors: Wang G. , Lin T. H. , Cheng P. C. 
Published: June 2010

AbstractTo overcome the limitations of Feldkamp's cone‐beam reconstruction algorithm, we generalized it in the case of noncircular and nonplanar scanning. In this paper, an error analysis is performed on this generalized approximate algorithm. The study is based on a reconstruction error formula. Roughly speaking, the error is proportional to the distance from a voxel to the mid‐plane in the planar scanning mode, to the pitch of a scanning locus in the helix‐like scanning mode, and inversely proportional to the horizontal size of the scanning locus. The error also depends on longitudinal variation of a specimen function. Longitudinal partial derivative distributions of specimen transverse sections are modeled as stochastic fields. Practical factors are simulated as noise terms in the reconstruction error formula. The simulation results show that the generalized Feldkamp's algorithm is not sensitive to noise and allows more accurate reconstruction in the helix‐like scanning mode.
Measuring the performance of scanning electron microscope detectors
Authors: Joy David C. , Joy Carolyn S. , Bunn Rodney D. 
Published: June 2010

AbstractA simple digital method of measuring the performance of detectors in the scanning electron microscope (SEM) is described. The value derived is absolute and can therefore be used to compare both different detectors on the same instrument as well as different detectors on different instruments. The technique can be applied to secondary electron, backscattered electron, and energy‐dispersive x‐ray detectors. Examples are given of measurements made on a variety of commercial detectors installed on a number of current SEMs.
Collection deficiencies of scanning electron microscopy signal contrasts measured and corrected by differential hysteresis image processing
Authors: Peters Klaus‐Ruediger 
Published: June 2010

AbstractLimitations of scanning electron microscopy (SEM) image resolution and quality were measured in digital image data and their effect on image contrasts was analyzed and corrected by differential hysteresis (DH) processing. DH processing is a mathematical procedure that utilizes hysteresis properties of intensity variations in the image for a segmentation of differential contrast patterns. These patterns display contrast properties of the data as coherent full‐frame images. The contrast segmentation is revertible so that the original image can be restored from the sum of the sequentially extracted DH contrast patterns. DH imaging enhances weak contrast components so that they are more easily recognizable and displays SEM image data free of signal collection efficiency contrasts. Example image data include environmental SEM (ESEM) and SEM images of low and mediumhigh magnifications where collection deficiencies included charging of the specimen surface, obstructions from specimen topography, and uneven signal collection properties of the detector. ESEM low‐vacuum image data, which appear to be of high quality, contained local areas of reduced contrasts due to residual surface charging. In such areas, signal contrasts were reduced up to 80%, which suppressed most of the weak short‐range contrasts. In low‐magnification SEM images, up to 93% of the local high precision contrast was lost from the various adverse effects which diminished the pixel‐related contrast resolution of the microscope and resulted in images with low detail. Also, at medium magnification, surface charging effects dramatically reduced the image quality because contrasts resulting from local electron beam/specimen interactions were reduced by as much as 71%. DH imaging restored the local contrast losses by elimination of the collected distorted fraction of signal contrasts and reconstitution of the collected maintained fraction. Restored DH images are of superior quality and enhance the imaging capability of the conventional SEM. DH contrast segmentation provides an improved basis for the measurement of various signal contrast components and detector performances. The DH analysis will ultimately facilitate a precise deduction of specimen properties from extracted contrast patterns.
Local computed tomography via iterative deblurring
Authors: Donald Ge Wang , Snyder L. , Vanner Michael W. 
Published: June 2010

AbstractX‐ray computed tomography is a major imaging modality. An iterative deblurring method is adapted for local reconstruction in parallel‐beam and cone‐beam geometries, utilizing only x‐rays passing through a region of interest. The feasibility is demonstrated in numerical simulation with noise‐free and noisy projection data. The iterative deblurring method has the theoretical advantages of maintaining nonnegativity, converging monotonically and minimizing Csiszàr's I‐divergence.
CASINO: A new monte carlo code in C language for electron beam interactions—part II: Tabulated values of the mott cross section
Authors: Drouin Dominique , Hovington Pierre , Gauvin Raynald 
Published: June 2010

AbstractThis paper presents routines to compute the Mott cross section used in the CASINO program (Monte CArlo SImulation of electroN trajectory in sOlid). The routines used tabulated values of the Mott cross section computed in the work of Czyzewski et al. (1990). The cross section is available over the range 0.02 to 30 keV and for the first 94 elements of the Periodic Table. The routines are written in C language and use a binary file to interpolate the cross section. The first routine computes the total Mott cross sections; the second calculates the polar angle of collision. Backscattered coefficients computed using different cross section are compared for C, Al, Ag, and Au. The Rutherford (1911) cross section and the available empirical equations (Browning et al. 1994, Gauvin and Drouin 1993) are compared to tabulated values of Mott. Also, the energy distribution of backscattered electrons is shown for Al and Au at 10 keV. Finally, the relative computation times for the different Mott cross sections are compared. It was found that tabulated Mott cross sections are more accurate and faster than any empirical Mott cross sections. The tabulated Mott cross sections are even faster than simple Rutherford cross sections.
Development of environmental scanning electron microscopy electron beam profile imaging with self‐assembled monolayers and secondary ion mass spectroscopy
Authors: Wight Scott , Gillen Greg , Herne Tonya 
Published: June 2010

AbstractA method for demonstrating the scattering of the primary electron beam in the presence of a gas has been developed. A self‐assembled decanethiol monolayer is damaged by primary beam electrons. The damaged portion of the mono‐layer is exchanged with another thiol‐containing molecule by immersion in solution. The resulting film is imaged using a secondary ion mass spectrometer. Three‐dimensional reconstruction of the data yields a representation of scattered electrons in the gaseous environment of the environmental scanning electron microscope.
A new correction method for high‐resolution energy‐dispersive x‐ray analyses in the environmental scanning electron microscope
Authors: Doehne Eric 
Published: June 2010

AbstractSpurious x‐ray signals, which previously prevented high‐resolution energy‐dispersive x‐ray analysis (EDS) in the environmental scanning electron microscope (ESEM), can be corrected using a simple method presented here. As the primary electron beam travels through the gas in the ESEM chamber, a significant fraction of the primary electrons is scattered during collisions with gas molecules. These scattered electrons form a broad skirt that surrounds the primary electron beam as it impacts the sample. The correction method assumes that changes in the width of the electron skirt with pressure are less important than changes in the skirt intensity; this method works as follows: The influence of the gas on the overall x‐ray data is determined by acquiring EDS spectra at two pressures. Subtracting the two spectra provides us with a difference spectrum which is then used to correct the original data, using extrapolation, back to the x‐ray spectrum expected under high‐vacuum conditions. Low‐noise data are required to resolve small spectral peaks; however, the principle should apply equally to x‐ray maps and even to low‐magnification images.
Some aspects of optimizing contrasts for the investigation of joint materials in the environmental scanning electron microscope
Authors: Schnarr Holger , Füting Manfred W. 
Published: June 2010

AbstractIn the environmental scanning electron microscope, material joints of different atomic mass and different electrical conducting properties can easily be observed simultaneously without coating the specimen. For such heterogeneous materials, the quality of the image can be optimized with respect to contrast and resolution if the contrast types as well as their significance to the composition of the image are known.
Use of the environmental scanning electron microscope for the observation of the swelling behaviour of cellulosic fibres
Authors: Jenkins L. M. , Donald A. M. 
Published: June 2010

AbstractWe have developed a method for observing transverse swelling of cellulosic fibres in the environmental scanning electron microscope (ESEM). The presence of liquid water in the ESEM specimen chamber allows the observation of in situ hydration without the need for coating, freezing, or drying of the sample. For reproducibility of the hydration and dehydration process, specialised mounting techniques are required and control of the conditions for condensation and evaporation of liquid water is necessary. The sensitivity of these cellulosic materials to the electron beam was investigated, showing that some damage mechanisms are enhanced by the continual presence of water vapour in the chamber. A discussion is presented of the effect of various experimental parameters on the extent and time of onset of the damage, and we outline steps to maximise the amount of useful experimental time for these fibres.
Environmental scanning electron microscopy of personal and household products
Authors: Hoyberg Karen 
Published: June 2010

AbstractThe ability to forego sample preparation and to make observations directly in the environmental scanning electron microscope has benefited both household and personal product research at Unilever Research. Product efficacy on biological materials such as microcomedones was easily ascertained. Skin biopsies were examined in a moist state with no sample preparation. Effects of relative humidity on detergents were visually determined by recreating the necessary conditions in the microscope. Effects of cooling rates on the morphology of softener sheet actives that remained on polyester fabric were characterized via dynamic experimentation.
Three‐dimensional studies of siC polytype transformations
Authors: Saparin G. V. , Obyden S. K. , Ivannikov P. V. , Shishkin E. B. , Mokhov E. N. , Roenkov A. D. , Hofmann D. H. 
Published: June 2010

AbstractScanning electron microscopy technique in colour cathodoluminescence mode is proposed for two‐dimensional (2‐D) and three‐dimensional (3‐D) studies of polytype structures of SiC epitaxial layers grown by the sublimation sandwich method. It allows us to perform layer‐by‐layer structure analysis of a polytype on depths up to 2.5 μm with high resolution. An effect of polytype instability under growth on singular substrate (0001) is revealed. It leads to the fact that the grown SiC layer represents the set of alternating sublayers of different polytypes such as 4H, 6H, and 3C. Some mechanisms of polytype syntaxy in SiC are discussed.
Double‐layer coating for field‐emission cryo‐scanning electron microscopy—present state and applications
Authors: Walther P. , Müller M. 
Published: June 2010

AbstractImaging of fast‐frozen samples is the most direct approach for electron microscopy of organic material. It prevents chemical fixation and drying artifacts. Frozen samples can be replicated and imaged in the transmission electron microscope (TEM), or they can be directly visualized in the cryo‐scanning electron microscope (cryo‐SEM). Double‐layer coating combines these two techniques and many of their advantages. With this method, the frozen bulk sample is coated similar to the TEM‐replica technique with, for example, a shadow of platinum (at an angle of 45°) and an additional layer of carbon. Then, the sample is cryo‐transferred to an SEM equipped with a cold stage and imaged with the material‐dependent backscattered electron signal that shows the platinum distribution. With this method, charging artifacts and the effects of beam damage are significantly reduced. Although currently the resolution of the replica technique cannot be surpassed, the method greatly facilitates the processing of brittle, rapidly frozen samples because no replica cleaning is necessary. This makes the method especially suitable for high‐pressure frozen samples.
Macromolecular substructure in nuclear pore complexes by in‐lens field‐emission scanning electron microscopy
Authors: Allen T. D. , Bennion G. R. , Rutherford S. A. , Reipert S. , Ramalho A. , Kiseleva E. , Goldberg M. W. 
Published: June 2010

AbstractScanning electron microscopy (SEM) has produced a wealth of novel images that have significantly complemented our perception of biological structure and function, derived initially from transmission electron microscopy (TEM) information. SEM is a surface imaging technology, and its impact at the subcellular level has been restricted by reduced resolution in comparison with TEM. Recently, SEM resolution has been considerably improved by the advent of high‐brightness sources used in field‐emission instruments (FEISEM) which have produced resolution of around 1 nm, virtually equivalent to TEM “working resolution.” Here we review our findings in the use of FEISEM in the imaging of nuclear envelopes and their associated structures, such as nuclear pore complexes, and the relationships of structure and function. FEISEM allows the structurally orientated cell biologist to visualise, directly and in three dimensions, subcellular structure and its modulation with a view to understanding its functional significance.
Atomic force microscopy as a tool for study of human hair
Authors: You H. , Yu L. 
Published: June 2010

AbstractAtomic force microscopy (AFM) is a newly developed microscopic technique that offers high‐resolution power, less intrusive measurement, and requires little sample pretreatment for elucidating structures of biological materials in three dimensions and in their natural environment. In this study, AFM has been used not only as an imaging technique for examining human hair structure at high resolution, but also as a tool for quantitative assessment of the effect of treatment in 10 mM phosphate buffered saline of pHs 3.0, 7.0, and 11.0 and heating on human hair structure. It is observed that the hair cuticle is a sensitive indicator of external influences on hair structure, and that its height can be used as a parameter for quantitative assessment. The experimental results obtained show that the swelling of hair caused by the incubation in the buffer decreases with the increase of the pH values and that, depending on the duration of heating, the hair undergoes structural expansion and shrinkage. This study demonstrates that AFM can be used as a valuable alternative to conventional microscopic techniques for hair research.