bluuebunny/crossref_metadata_2025 huggingface dataset:
Measures for spectral quality in low‐voltage X‐ray microanalysis
Authors: Newbury Dale E.
Published: June 2010

Characteristic x‐ray production with energetic electrons depends strongly on the overvoltage, the ratio of the incident beam energy to the critical excitation energy for the atomic species of interest. Low‐voltage x‐ray micro‐analysis (beam energy ≤ 5 keV) is especially susceptible to artifacts due to sample charging because the overvoltage is low and even slight charging can strongly affect peak intensities. The Duane‐Hunt bremsstrahlung limit is a good diagnostic to detect sample charging. Dynamic charging effects, however, can influence spectra despite an apparently satisfactory Duane‐Hunt limit. Dynamic charging effects must be examined by time series experiments, or through use of dynamic energy windows continuously measuring count rates placed across the spectrum. When charging is a problem, conductive surface coatings can eliminate the effects. When pristine surfaces must be examined without coating, the use of a conductive grid can control charging so that useful x‐ray spectra can be obtained.
Investigation of foreign substances in food
Authors: Charbonneau James E.
Published: June 2010

Scanning electron microscopy (SEM) together with energy‐dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) were used to investigate foreign substances from seven categories of foreign substances in food. (1) Naturally occurring foreign substances—Using FTIR, a foreign substance was identified as a natural resin probably from the product. (2) Foreign substances introduced during food processing. Scanning electron microscopy‐EDS was used to identify a foreign material found on surf clams as calcium phosphate from a product/ingredient interaction. Using SEM‐EDS, a crystalline material in a meat product was identified as calcium salts of chloride and phosphate. Fourier transform infrared spectroscopy was used to identify foreign material that clogged an aerosol valve as chipboard. Using SEM‐EDS, the metal in the heel of a glass bottle was identified as copper sulfide‐containing metal inclusion. (3) Insects, reptiles, and rodents—Scanning electron microscopy was used to determine that a mouse found in food was not processed with the food, but entered the container after it left the factory. (4) Glass fragments—Glass from various sources can be distinguished from one another using SEM‐EDS either by the level of the major elements in glass or by the presence of elements in one glass, but not in another. (5) Glass‐like particles—Using SEM‐EDS, glass‐like particles found on beets were determined to be a fatty acid. (6) Metal foreign objects—Using SEM‐EDS, metals from a variety of sources can be easily distinguished. For example, a tin‐soldered container can be distinguished from a lead‐soldered can. Using SEM‐EDS, the metal fiber found on the bottom of a two‐piece can likely enter the can during the final stage of the manufacture of the drawn and ironed food can. (7) Drug capsule identification—Fourier transform infrared spectroscopy was used to determine that a pill found in food was ibuprofen.
On the electrical properties of dislocations in ZnS using electric force microscopy
Authors: Bai G. F. , Petrenko V. F. , Baker I.
Published: June 2010

A combination of electric force microscopy (EFM) and noncontact atomic force microscopy (AFM) was used to study microscratching‐induced dislocations in sphaleritic ZnS single crystals. Dislocation bands predominantly consisting of either anion‐type (S) or cation‐type (Zn) dislocations were induced by scratching along either [111] or [111] on a (110) surface. A significant difference of local distortions in electrical potential between the S(g) and Zn(g) dislocation bands was observed from the EFM images. Electric charges of these dislocations were determined quantitatively and the results were compared with theoretical models.
Mapping piezoelectric‐field distribution in gallium nitride with scanning second‐harmonic generation microscopy
Authors: Sun Chi‐Kuang , Chu Shih‐Wei , Tai Shi‐Peng , Keller Stacia , Abare A. , Mishra U. K. , Denbaars Steven P.
Published: June 2010

Taking advantage of the electric field‐enhanced second‐harmonic generation effect in bulk gallium nitride (GaN) and indium gallium nitride (InGaN) quantum wells, we demonstrated the piezoelectric field distribution mapping in bulk GaN and InGaN multiple‐quantum‐well (MQW) samples using scanning second‐harmonic generation (SHG) microscopy. Scanning SHG microscopy and the accompanying third‐harmonic generation (THG) microscopy of the bulk GaN sample were demonstrated using a femtosecond Cr:forsterite laser at a wavelength of 1230 nm. Taking advantage of the off‐resonant electric field‐enhanced SHG effect and the bandtail state‐resonance THG effect, the second‐ and third‐harmonic generation microscopic images obtained revealed the piezoelectric field and bandtail state distributions in a GaN sample. Combined with 720 nm wavelength excited two‐photon fluorescence microscopy in the same sample, the increased defect density around the defect area was found to suppress bandedge photoluminescence, to increase yellow luminescence, to increase bandtail state density, and to decrease residue piezoelectric field intensity. Scanning SHG microscopy of the InGaN MQW sample was resonant excited with 800 nm femtosecond pulses from a Ti:sapphire laser in order to suppress SHG contribution from the bulk GaN substrate. Taking advantage of the strong piezoelectric field inside the InGaN quantum well, the wavelength resonant effect, and the electric field‐enhanced SHG effect of InGaN quantum wells, resonant scanning SHG microscopy revealed the piezoelectric field distribution inside the wells. Combined with accompanying three‐photon fluorescence microscopy from the bulk GaN substrate underneath the quantum wells, the direct correspondence between the piezoelectric field strength inside the quantum well and the substrate quality can be obtained. According to our study, the GaN substrate area with bright bandedge luminescence corresponds to the area with strong SHG signals indicating a higher stained‐induced piezoelectric field. These scanning harmonic generation microscopies exhibit superior images of the piezoelectric field and defect state distributions in GaN and InGaN MQWs not available before. Combining with scanning multiphoton fluorescence microscopy, these techniques open new ways for the physical property study of this important material system and can provide interesting details that are not readily available by other microscopic techniques.
A high‐resolution add‐on in‐lens attachment for scanning electron microscopes
Authors: Khursheed A. , Karuppiah N. , Koh S. H.
Published: June 2010

A compact add‐on objective lens for the scanning electron microscope (SEM) has been designed and tested. The lens is < 35 mm high and can be fitted on to the specimen stage as an easy‐to‐use attachment. Initial results show that it typically improves the spatial resolution of the SEM by a factor of three. The add‐on unit is based upon a permanent magnet immersion lens design. Apart from the extra attachment to the specimen stage, the SEM with the add‐on lens functions in the normal way. The in‐lens unit can comfortably accommodate specimen heights up to 10 mm. The new add‐on lens unit opens up the possibility of operating existing SEMs in the high‐resolution in‐lens mode. By using a deflector at the top of the add‐on lens unit, it can also operate as a quantitative multichannel voltage contrast spectrometer, capable of recording the energy spectrum of the emitted secondary electrons. Initial experiments confirm that a significant amount of voltage contrast can be obtained.
A comparison of surface roughness of pipes as measured by two profilometers and atomic force microscopy
Authors: Farshad Fred F. , Pesacreta Thomas C. , Garber James D. , Bikki S. R.
Published: June 2010

The objective of this study was to develop a reliable method for the measurement of pipe surface roughness. Roughness of coated pipe was measured with two linear surface profilers, a Dektak3ST® and a Hommel T 1000, and a Dimension 3000® atomic force microscope (AFM). Arithmetic roughness (Ra), root mean square roughness (Rq), and mean peak‐to‐valley height (RZD) were statistically analyzed. Each instrument yielded reliable results, but there were significant differences between the AFM and the other two instruments. The ability of RZD to ignore intermediate height data while focusing on extreme height data made it a useful parameter for detecting differences in height that would be the most likely to affect fluid flow in pipes.
The use of secondary ion mass spectrometry coupled with image analysis to identify and locate chemical elements in soil minerals: The example of phosphorus
Authors: Bertrand Isablle , Grignon Nicole , Hinsinger Philippe , Souche Gérard , Jaillard Benoǐt
Published: June 2010

The mobility andbioavailability of elements in soils and sediments largely depends on their distribution on the diverse inorganic and organic constituents. This work addresses the example of phosphorus (P) associated to goethite and calcite, that is, to the major minerals involved in the retention of P in soils and sediments in calcareous environments. Synthetic goethite (FeOOH) and calcite (CaCO3) were reacted with P prior to being analysed by dynamic secondary ion mass spectrometry (SIMS). Powdery samples were embedded in resin, cut in thin sections, and imaged with a Cameca IMS 4F ion microscope used in scanning mode with a primary ion beam of caesium that produced negatively charged secondary ions (−) (Cameca, Cedex, France). Carbon, O, P, and calcium (Ca) were directly imaged at m/z 12, 16, 31, and 40, respectively, while Fe was imaged via the polyatomic ion FeO− ion at m/z 72. The SIMS data were treated by image analysis procedures. The visual comparison of images and the scatterplot method showed that P strongly interacted with goethite, probably following an adsorption process, and was thus evenly distributed at its surface. Conversely, P was not evenly distributed at the surface of calcite which rather suggests a precipitation process, and the scatterplot method confirmed a poor relationship between P and Ca. For the goethite‐calcite mixture, visual examination suggested that P occurred as clusters which were largely associated with calcite, whereas a statistical analysis of the various images showed that the distribution of P was largely related to that of goethite particles. This work confirms the potential contribution of iron oxides in the retention of P in calcareous environments and shows that coupling image analysis to sensitive analytical techniques such as SIMS is a powerful approach for providing quantitative information on the location of elements at low bulk concentrations.
Experimental data and model simulations of beam spread in the environmental scanning electron microscope
Authors: Wight Scott A.
Published: June 2010

This work describes the comparison of experimental measurements of electron beam spread in the environmental scanning electron microscope with model predictions. Beam spreading is the result of primary electrons being scattered out of the focused beam by interaction with gas molecules in the low‐vacuum specimen chamber. The scattered electrons form a skirt of electrons around the central probe. The intensity of the skirt depends on gas pressure in the chamber, beam‐gas path length, beam energy, and gas composition. A model has been independently developed that, under a given set of conditions, predicts the radial intensity distribution of the scattered electrons. Experimental measurements of the intensity of the beam skirt were made under controlled conditions for comparison with model predictions of beam skirting. The model predicts the trends observed in the experimentally determined scattering intensities; however, there does appear to be a systematic deviation from the experimental measurements.
Single‐image signal‐to‐noise ratio estimation
Authors: Thong J. T. L. , Sim K. S. , Phang J. C. H.
Published: June 2010

A method for estimating the signal‐to‐noise ratio from a single image is presented in this paper. The autocorrelation‐based technique requires that image details be correlated over distances of a few pixels, while the noise is assumed to be uncorrelated from pixel to pixel. The latter is shown to be a good approximation in the case of scanning electron microscope (SEM) images provided that the video signal is not band limited. The noise component is derived from the difference between the image autocorrelation at zero offset and an estimate of the corresponding noise‐free autocorrelation. Nonlinear effects introduced by intensity saturation and their implications on the image signal‐to‐noise ratio are also discussed.
Direct wet surface imaging of an anaerobic biofilm by environmental scanning electron microscopy: Application to landfill clay liner barriers
Authors: Darkin M. G. , Gilpin C. , Williams J. B. , Sangha C. M.
Published: June 2010

To contain domestic waste and its associated pollution within a landfill, engineered mineral (clay) barriers are used and are designed to have a permeability of 1×10−9 m/s (Westlake 1995). The rate of permeability of various porous media has shown to be influenced by the clogging of flow paths (media pores) due to biofilm formation (Charckalis and Marshall 1990, Cunningham et al. 1991). The term biofilm is given to describe the colonies of surface adherent microorganisms (Donlan et al. 1994). In this study, permeability experiments were built and modified to act as microcosms to investigate the influence of biofilm formation on the permeability of clay barriers. Traditional scanning electron microscopy methods disrupt or destroy the biofilm and previous anaerobic studies have involved building closed cells (such as miniature continuous culture chambers) that utilise light microscopes (Robin Jones et al. 1997). This paper examines the application of the environmental scanning electron microscope (ESEM) to the direct examination of the clay interface and biofilm formation in situ within the microcosm.
Strategies for optimum use of superposition diffractogram in scanning electron microscopy
Authors: Oho Eisaku , Toyomura Kenji
Published: June 2010

Characteristics of the superposition diffractogram used for precisely estimating scanning electron microscopy (SEM) resolution are investigated. It is shown that the choice of pixel density to satisfy the sampling theorem, the direction of scanning, the choice of image shift direction, the properties of the specimen, the effect of external disturbances such as vibration and stray magnetic fields, and the effect of the window function required in the Fourier transform, are all factors which must be considered in order to make the superposition diffractogram a practical technique. An additional important improvement required to exploit fully the ability of the superposition diffractogram, which potentially is very high, is a special scanning mode which employs a digital scan generator, and digital image processing technology with autocorrelation functions.
Three‐dimensional visualization and physiologic evaluation of bile canaliculi in the rat liver slice by confocal laser scanning microscopy
Authors: Yoneyama Keiichiro
Published: June 2010

We evaluated the morphology and physiologic function of the bile canaliculi (BC) in the rat liver slice (RLS) by confocal laser scanning microscopy (CLSM). Lucifer yellow (LY) dye was injected into the RLS, and the distribution of LY was serially evaluated. After the injection of LY, hepatocytes were initially visualized, followed by visualization of the BC. There was no significant difference in the distribution of LY between zones 1 and 3 in the hepatic lobule. In zone 1, the reticular distribution of the BC was observed, whereas the part of BC was linearly visualized in zone 3 along the course of sinusoids. When changes in the bile canalicular fluorescence (BCF) were serially evaluated, the BCF was decreased to the minimal level (88% of the value obtained immediately after the LY injection) 10 min after the LY injection, and it tended to increase thereafter. The intralobular hepatocyte fluorescence (ILHF) was decreased to 58.9% of the initial value during the first 40 min. However, the ILHF was transiently increased 30 min after the LY injection, suggesting the possibility of reabsorption of LY by hepatocytes. Three‐dimensional (3‐D) reconstruction images of the BC facilitated the evaluation of the stereoscopic structure of BC. Confocal laser scanning microscopy facilitated the evaluation of structures and physiologic function of the BC.
Imaging of specimens at optimized low and very low energies in scanning electron microscopes
Authors: Müllerová Ilona
Published: June 2010

The modern trend towards low electron energies in scanning electron microscopy (SEM), characterised by lowering the acceleration voltages in low‐voltage SEM (LVSEM) or by utilising a retarding‐field optical element in low‐energy SEM (LESEM), makes the energy range where new contrasts appear accessible. This range is further extended by a scanning low‐energy electron microscope (SLEEM) fitted with a cathode lens that achieves nearly constant spatial resolution throughout the energy scale. This enables one to optimise freely the electron beam energy according to the given task. At low energies, there exist classes of image contrast that make particular specimen data visible most effectively or even exclusively within certain energy intervals or at certain energy values. Some contrasts are well understood and can presently be utilised for practical surface examinations, but others have not yet been reliably explained and therefore supplementary experiments are needed.
Reduction of charging effects using vector scanning in the scanning electron microscope
Authors: Thong J. T. L. , Lee K. W. , Wong W. K.
Published: June 2010

We describe a vector scanning system to reduce charging effects during scanning electron microscope (SEM) imaging. The vector scan technique exploits the intrinsic charge decay mechanism of the specimen to improve imaging conditions. We compare SEM images obtained by conventional raster scanning versus vector scanning to demonstrate that vector scanning successfully reduces specimen‐charging artifacts.
Interaction of maize zein with wheat gluten in composite dough and bread as determined by confocal laser scanning microscopy
Authors: Bugusu Betty A. , Hamaker Bruce R. , Rajwa Bartlomiej
Published: June 2010

Protein body‐free maize zein, when mixed at 35°C (above its glass transition temperature range), significantly (p < 0.01) improved the rheological and leavening properties of sorghum‐wheat composite flour dough, resulting in improved loaf volume. Confocal laser scanning microscopy was used to observe the structure of zein fibrils and the interaction between zein and gluten proteins in the composite dough and bread systems. Autofluorescence and immunolocalization techniques were used to locate gluten and zein, respectively. Optical sections were collected every 0.4 μm through the samples and digitally processed to produce reconstructed three‐dimensional images. Results showed that zein fibrils form an outer layer that intermittently coats the gluten networks, thereby strengthening them. This type of microstructure is able to withstand the pressure exerted by gas cell expansion during yeast fermentation to increase loaf volume.
Development of preparation methods for and insights obtained from atomic force microscopy of fluid spaces in cortical bone
Authors: Knapp Helmut F. , Stemmer Andreas , Reilly Gwendolen C. , Niederer Peter , Tate Melissa L. Knothe
Published: June 2010

Several preparation methods were developed to investigate the dimensions and surface structure of fluid spaces within cortical bone, using atomic force microscopy (AFM). Of special interest was the morphology of the lacunocanalicular system, which serves as a conduit between osteocytes encased in bone tissue, the intramedullary cavity, blood vessels running through the bone, and the periosteal surface of bone. Fracture and the removal of either the mineral or the organic component is a method by which each component can be investigated at a very high resolution in situ. Although fractured bone was too rough to image details of the lacunocanalicular system, post‐treatment with ethylene diamine tetraacetic acid (EDTA) or pa‐pain allowed for investigation of the collagen matrix or the mineral crystals of bone, respectively. Cut and polished bone was smooth enough for identifying the lacunae of bone using AFM, but unambiguous differentiation between the canaliculi and cracks in the bone surface was not possible. However, when the lacunocanalicular system was filled with polymethylmethacrylate (PMMA), it was possible to image casts of the lacunocanalicular system by selectively etching away the surrounding bone matrix. Using this method, we identified individual canaliculi and measured their dimensions. Furthermore, by carefully etching away the bone matrix in successive etches, it was shown that the wall structure of the canaliculus is dominated by collagen fibrils. These observations have important implications for fluid flow in bone.
Line profile reconstruction from simultaneously recorded secondary and backscattered electron signals
Authors: Li Xiaoyuan , Uchikawa Yoshiki , Kodama Tetsuji , Mori Yuki
Published: June 2010

We propose a reconstruction method of surface morphology using a combination of secondary and back‐scattered electron signals from the scanning electron microscope (SEM). Compared with multiple‐detector methods, the proposed system requires only conventional secondary and backscattered electron detectors for a line profile reconstruction in one direction. This method is an application of genetic algorithms to the measurement of surface morphology in SEM. We use the chi‐square distribution of the reconstruction error as the objective function within a scheme to minimize the number of vertices in the reconstructed surface profile. (The reconstruction error is the relative difference between the calculated and experimental data.) To evaluate the efficacy of our method, a surface profile is successfully reconstructed from a pair of line scans across the center of a latex particle.
The method for the reconstruction of complex images of specimens using backscattered electrons
Authors: Kaczmarek Danuta , Domaradzki Jaroslaw
Published: June 2010

The backscattered electron signal (BSE) is widely used for investigation of specimen surfaces in a scanning electron microscope (SEM). The development of multiple detector systems for BSE signal detection and the methods of digital processing of these signals have allowed for reconstruction of the third dimension on the basis of the two‐dimensional (2‐D) SEM image. A technique for simultaneous mapping of material composition (COMPO mode) and reconstruction of surface topography (TOPO mode) has also been proposed. This method is based on the measurements of BSE currents sensed by four semiconductor detectors versus the inclination angle of surface. To improve the separation of topographic and material contrasts in SEM, a correction of the TOPO and COMPO modes (resulting from a theoretical description of the system: electron beam, specimen, and detector) was applied. The proposed method can be used for a correct reconstruction of the surface image when the surface slope is <60°. The measuring limit of the slope was closely connected with the detector setup. Next, the digital simulation of the colors was performed (after application of the method of linearization of BSE characteristic versus atomic number). This procedure to increase the SEM resolution for the BSE signal by use of digital image processing allows for a better distinction between the two elements with high atomic numbers.
Energy distribution of electron backscattering from crystals and relation to electron backscattering patterns and electron channeling patterns
Authors: Berger Dirk , Niedrig Heinz
Published: June 2010

This paper reports on the influence of the channeling effect on the energy distribution of electrons backscattered from crystals with different atomic numbers Z. These results can be used for the optimization of the contrast of electron backscattering and electron channeling patterns.

Energy and angular resolved electron scattering distributions are obtained using a 4‐axial experimental setup with a moveable high‐resolution spherical spectrometer. Special care is taken to suppress undesired reflections of electrons inside the spectrometer. This experimental setup allows the direct observation of the excitation of different Bloch waves (anomalous absorption and transmission) within the crystal for different electron incidence angles and the observation of angular distributions of elastically scattered electrons. Results are presented for Si and Au monocrystals, showing that the influence of the channeling effect is more distinct for low atomic numbers.
Conditions for imaging emulsions in the environmental scanning electron microscope
Authors: Mathews R. G. , Donald A. M.
Published: June 2010

Environmental scanning electron microscopy (ESEM) is a technique capable of imaging volatile and/or insulating samples in their natural state, without prior specimen preparation. It is thus a powerful potential tool for the study of the structure and dynamics of emulsions and other complex liquid systems, at a resolution greater than that obtainable by conventional optical microscopy. We present images of a variety of liquid systems containing micronscale and smaller features. The morphology of these systems may be clearly discerned. The contrast observed between the liquid phases was consistent with the model proposed by Stokes et al. (1998). The limits of resolution were determined by sample motion and by beam damage effects; under optimum conditions, resolution of a few tens of nanometers was obtained. This compares favourably with conventional and confocal optical microscopy. In some samples, thin films (solid or liquid) could be observed at the liquid/gas interface. Some of these films were so thin that they did not completely obscure the underlying structure of the bulk sample.
Automatic Integrated Circuit Die Positioning in the Scanning Electron Microscope
Authors: Tan H. W. , Phang J. C. H. , Thong J. T. L.
Published: June 2010

In scanning electron microscope (SEM)‐based integrated circuit (IC) failure analysis, there is often a need for manual location of a prespecified failure site in several ICs. Such a procedure is both tedious and time consuming. This paper presents a new vision‐based die positioning system that can automatically locate a specified failure site without the need for a high‐accuracy specimen stage. Depending on the appearance of the desired failure site, the system applies either image registration or feature tracking to locate the site. Experiments performed on a variety of IC samples show that the system is able to locate the failure site accurately, even in the presence of unfavorable conditions such as IC sample rotation and repetitive IC patterns.
Automated analysis of submicron particles by computer‐controlled scanning electron microscopy
Authors: Poelt P. , Schmied M. , Obernberger I. , Brunner T. , Dahl J.
Published: June 2010

Automated analysis of submicron particles by computer‐controlled scanning electron microscopy is generally possible. The minimum diameter of the detectable particles is dependent on the mean atomic number of the particles and the operating parameters of the scanning microscope. The main limitation with regard to particle size is set by the quality of the particle detection system, which generally is the backscatter electron detector. The accuracy of the results of the x‐ray analyses is very often strongly affected by specimen damage, omnipresent especially for environmental particles even at low electron energies and probe currents. With the exception for light elements, the detection limit is approximately 1 wt%. Device‐related limitations to automated analysis may be specimen drift and an unreliable autofocus function.
Guiding Self‐Assembly with the Tip of an Atomic Force Microscope
Authors: Mesquida Patrick , Stemmer Andreas
Published: June 2010

We report the guided self‐assembly of nanoparticles to geometrically well‐defined charge patterns written on a dielectric surface with the conductive tip of an atomic force microscope (AFM). Charges are deposited in 30‐90‐nm thick fluorocarbon layers by applying voltage pulses to the conductive AFM tip. The samples are being developed by dipping them into an organic suspension of silica nanoparticles. Coulomb forces draw the nanoparticles to the charge patterns. With this simple process, we achieve a resolution of about 800 nm.
Direct assessment of recombination noise in semiconductors using electron beam‐induced conductivity
Authors: Mil'shtein S.
Published: June 2010

The level of internal noise of the transistors, diodes, and other semiconductor components limits the successful design of any low noise electronic system. All types of noise, namely, Johnson, 1/f, and so forth, are generated due to activity of crystalline defects such as vacancies, dislocations, and others. The intensity of the electron scattering and recombination processes, inflicted by defects (traps), controls the level of noise. Dependent on the dynamic operation condition of semiconductor devices, such as external biases and level of current injection, the traps will generate certain type and level of noise. Material growth or device processing technologies could introduce all kind of defects. Therefore, characterization of the semiconductor wafer in the early stages of processing (at least before packaging) could help to predict the level of noise due to the type and density of defects present on the wafer. Sorting out bad semiconductor chips could save money and effort in the radio frequency design of low‐noise circuits. This current study focuses on 1/f noise modeling, which involves most powerful generators of noise and linear defects, named dislocations. The study also examines the possibility of assessing this noise by quantitative electron beam‐induced conductivity (EBIC) measurements. These defects could be found in the bulk as well as at the epitaxial interfaces of a semiconductor device. The nanoscale size of these defects makes the scanning electron beam an instrument of choice for the proposed study. Conventional EBIC produces images of the defects, where contrast is proportional to the recombination rate at the site of a defect. Since contrast is measured as a fraction of one percent, the relative nature of contract value precludes quantitative measurements of the recombination rate, thus making quantitative assessment of 1/f noise impossible. In our model, using the Boltzman continuity equation, the recombination‐generation processes per unit of length of a dislocation was defined for two operational conditions of EBIC, namely, for low and high intensity of an electron beam. The experimental technique of the quantitative measurement of carrier recombination (Mil'shtein 2001) consists of taking two EBIC scans along the selected defect at two different beam intensities, digitally subtracting the first scan from the second one and normalizing the result to the size of the electron range. The value of the recombination rate, extracted from the model, could then be used to predict the level of 1/f noise in the tested semiconductor sample.
Investigation of unusual inactivity of industrial platinum‐rhodium catalyst gauze
Authors: Lomic Gizela , Kis Erne , Marinkovic‐Neducin Radmila , Grabovac Marijana
Published: June 2010

The aim of this work was to obtain information about the causes of unusual lack of activation of fresh, unused, 90% platinum‐10% rhodium catalyst gauze that was detected after the activation process in an industrial ammonia oxidation plant. To reach the usual efficiency, it was necessary to regenerate the catalyst immediately after the activation procedure by using an acid bath. To avoid future unexpected shutdowns in the ammonia oxidation plant, the possible sources of impurities accumulated on the catalyst surface were investigated by an analysis of the experimental results and technological processes. The absence of accumulation on the unused catalyst surface eliminates the possibility of contamination during the preparation, while the composition of the impurities indicates that it cannot result from the reactor construction material. In mixed feedstock, detectable amounts of the poisons mentioned were not detected either after filtration or before the reactor. All these considerations imply that the time when the catalyst contamination occurred must have been before the contact with the gas mixture. From data obtained, it is hypothesized that the origin of this substance is from the polluted air in the industrial area where the ammonia oxidation plant is located and that the accumulation probably took place during the preparation of the catalyst pad.
Scanning tunneling microscope spectroscopy of polymers
Authors: Zypman Fredy R.
Published: June 2010

This paper presents theoretical results on the relationship between density of states (DOS) and scanning tunneling microscope current‐voltage curves in polymers. We considered samples of linear hydrocarbons electrically grounded at one of their extremes. The other extreme is electrically connected to the microscope tip via electron tunneling through vacuum. When a voltage, V, is applied to the tip, electric current, I, flows in the tip‐sample circuit. This current varies as the voltage varies and depends on the DOS to the extent that no current would flow if no electron states exist at a certain energy (or voltage). The detailed relationship between DOS and the current‐voltage (I‐V) curve is not known a priori. We solve the corresponding quantum problem in the context of tight binding and find that I‐V reproduces accurately the resonant energy peaks of the DOS. We apply the results to 100 atom‐long alkane and alkene chains and found that there is a significant voltage shift in the corresponding curves as to discriminate one structure from the other.
A prototype two‐detector confocal microscope for in vivo corneal imaging
Authors: Petroll W. Matthew , Jester James V. , Cavanagh H. Dwight , Yu Alex , Li Jie , Black Truman
Published: June 2010

Confocal microscopy through‐focusing (CMTF) of the cornea produces a three‐dimensional (3‐D) display of corneal structure and intensity profiles that allow objective measurements of corneal sublayer thickness and relative assessment backscattering of light. In this study, a prototype confocal instrument was evaluated in which a photon counting photomultiplier tube (PMT) detector was added to provide faster and more quantitative measurements, while still maintaining the imaging capability of the microscope. To acquire images and measure backscattered light simultaneously, an uncoated pellicle beam splitter was incorporated into the light path of the confocal microscope. This beam splitter reflects 8% of the confocal signal to the PMT. The CMTF scans were performed on four rabbits using the prototype instrument. Corneal images and 3‐D reconstructions acquired with and without the beam splitter in the light path appeared identical. Both the camera and PMT CMTF curves had easily identifiable peaks corresponding to the epithelium, basal lamina, and endothelium. No significant differences were found between PMT and camera CMTF measurements of epithelial, stromal, or corneal thickness (n=12 scans). Furthermore, a high correlation was found between camera and PMT measurements (linear regression analysis, y =0.999× −0.4, r=0.99, p<0.001). The data suggest that by adding a pellicle beam splitter, CMTF intensity data can be acquired using a PMT. The PMT has a faster sampling rate and greater dynamic range than the camera and provides a count of the photons detected. Thus, the instrument has the potential for improving corneal pachymetry and back‐scattering measurements while still providing high‐resolution corneal images.
A method to measure the effective gas path length in the environmental or variable pressure scanning electron microscope
Authors: Gauvin Raynald , Griffin Brendan , Nockolds Clive , Phillips Matthew , Joy David C.
Published: June 2010

A simple method is described to determine the effective gas path length when incident electrons scatter in the gas above the specimen. This method is based on the measurement of a characteristic x‐ray line emitted from a region close to the incident beam. From various experimental measurements performed on various microscopes, it is shown that the effective gas path length may increase with the chamber pressure and that it is also often dependent of the type of x‐ray bullet.
Two‐dimensional simulation and modeling in scanning electron microscope imaging and metrology research
Authors: Postek Michael T. , Vladár András E. , Lowney Jeremiah R. , Keery William J.
Published: June 2010

Traditional Monte Carlo modeling of the electron beam‐specimen interactions in a scanning electron microscope (SEM) produces information about electron beam penetration and output signal generation at either a single beam‐landing location, or multiple landing positions. If the multiple landings lie on a line, the results can be graphed in a line scan‐like format. Monte Carlo results formatted as line scans have proven useful in providing one‐dimensional information about the sample (e.g., linewidth). When used this way, this process is called forward line scan modeling. In the present work, the concept of image simulation (or the first step in the inverse modeling of images) is introduced where the forward‐modeled line scan data are carried one step further to construct theoretical two‐dimensional (2‐D) micrographs (i.e., theoretical SEM images) for comparison with similar experimentally obtained micrographs. This provides an ability to mimic and closely match theory and experiment using SEM images. Calculated and/or measured libraries of simulated images can be developed with this technique. The library concept will prove to be very useful in the determination of dimensional and other properties of simple structures, such as integrated circuit parts, where the shape of the features is preferably measured from a single top‐down image or a line scan. This paper presents one approach to the generation of 2‐D simulated images and presents some suggestions as to their application to critical dimension metrology.
Cryostatic micro‐computed tomography imaging of arterial wall perfusion
Authors: Kantor Birgit , Jorgensen Steven M. , Lund Patricia E. , Chmelik Michael S. , Reyes Denise A. , Ritman Erik L.
Published: June 2010

A double‐walled copper vessel, 32 cc in volume, was fabricated for scanning tissue specimens while maintained below freezing point. To keep specimen temperature within ±1°C, temperature sensors within the chamber control, the rate of inflow of the cold nitrogen gas vented through the chamber. The specimen is attached to a small platform on top of a vertical pin which is attached to the computer‐controlled rotating stage under the vessel. The purpose of this arrangement is to permit scanning of specimens up to 2 cm3 that (1) cannot be “fixed” (e.g., with formalin) because of analyses which are incompatible with prior fixation (certain immunohistochemistry and biomolecular methods), or (2) are “snap”‐frozen during a transient process, such as the accumulation and/or washout of radiopaque indicators. Examples of “cryoscans” of porcine carotid and coronary artery wall opacification in either untouched or acutely stented arteries, snap‐frozen immediately after selective intra‐arterial injection of a contrast agent, show accumulation of contrast in the extravascular space indicating increased endothelial permeability or endothelial and medial disruption following stent placement. The detection of contrast in the adventitia suggest that vasa vasorum deliver the contrast agent from the main lumen to the adventitial extravascular space but not to the media.
A method for personal expertise‐independent evaluation of image resolution in scanning electron microscopy
Authors: Ishitani Tohru , Sato Mitsugu
Published: June 2010

The two conventional methods currently employed for the evaluation of image resolution in scanning electron microscopy are the gap method and a fast Fourier transform (FFT) method. These can be highly dependent on personal expertise on the distinction between signal information and noise contained in a micrograph. Hence, the present paper proposes an alternative method (referred to as a contrast‐to‐gradient (CG) method) that can determine the image resolution of a micrograph without requiring personal expertise on the judgment of noise. The image resolution in the CG method is defined as a weighted harmonic mean of the local resolution, which is proportional to the quotient of the threshold contrast divided by the local gradient. The local gradient is calculated from the quadratic function that best fits the local pixel intensities over 5 × 5 pixels. It has been shown that the CG method, compared with the FFT method, has a broader range of applications for various types of images, such as low‐contrast, noise‐containing, filter‐processed, highly directional, and quasi‐periodic feature images.
Determination of a translocation chromosome by atomic force microscopy
Authors: Ergun Mehmet Ali , Karaoguz Meral Yirmibes , Ince Gonul Didem , Menevse Adnan , Tan Erdal
Published: June 2010

Atomic force microscopy (AFM) has been used to study the translocation involving chromosomes 11 and 13. An amniocentesis procedure was performed at 18 weeks of pregnancy on a familial balanced translocation carrier mother whose karyotype was 46, XX, t(11;13) (q23;q34). After harvesting the tissue cultures, light microscopy studies (LM) have indicated that the fetus had the same translocation. A 0.3 μm gap region on the derivative chromosome 13 was determined by AFM; it was equivalent to a mid‐sized G‐band. The enhanced resolution of AFM with respect to its line measure analysis and three‐dimensional image capture capability has allowed an extension and reconsideration of conclusions about chromosomal aberrations based on the study of LM preparations. In this manner, chromosomal disorders will be studied at nanoscale to help in the planning of new therapy strategies.
Morphologic variations in bacteria under stress conditions: Near‐ field optical studies
Authors: Cefalì E. , Patanè S. , Arena A. , Saitta G. , Guglielmino S. , Cappello S. , Nicolò M. , Allegrini M.
Published: June 2010

The morphologic and structural variations suffered by cells of a population of Pseudomonas aeruginosa ATCC 27853 under stress conditions were investigated by using scanning near‐field optical microscopy. The analysis of the images, supported by microbiological data, showed that the bacteria evolved from the initial distribution of rod‐shaped cells of standard size to a population with structural and morphologic modifications. The detection of variations in the optical reflectivity over a sub‐wavelength scale (⩽ 100 nm), combined with the concurrently acquired topographical signal, allowed the visualisation of rod‐shaped bacteria going towards a lytic process and entire “U”‐shaped cells. In the latter cells, which derived from a morphology refolding of rod bacteria, cellular matter seemed to rearrange itself to attain a coccoid stress resistant form, responsible for the residual viability of the population.
Confocal Endoscopy via Structured Illumination
Authors: Karadaglić D. , Juškaitis R. , Wilson T.
Published: June 2010

We describe a simple modification to a rigid endoscope so as to provide both high‐quality conventional and confocal images of reasonably accessible regions of the body. This versatile system uses a structured illumination approach together with a conventional incoherent illumination source. Images taken in fluorescence are presented using this combined conventional and confocal endoscope.
Cytochrome Oxidase Activity and Confocal Laser Scanning Microscopic Analysis of the Hamster Submandibular Gland Using Microwave Irradiated Fixation
Authors: Moriguchi K. , Utsumi M. , Maeda H. , Kameyama Y. , Ohno N.
Published: June 2010

Submandibular glands of the hamster were irradiated in 2% paraformaldehyde (pFA)‐0.5% pure glutaraldehyde (PGA) with a microwave (MW) processor at temperatures of 10° and 37°C. Electron microscopy showed that cytochrome oxidase activity was taking place in the mitochondrial intermembrane‐intracristal space of the granular duct cell when the temperature of the MW‐irradiated fixatives was at 10°C. However, a decrease of this activity was observed when we took care to keep the temperature of the MW‐irradiated fixatives at 37°C. The distinct reduction of cytochrome oxidase activity allowed by MW irradiation seems to be due the thermal affects of fixatives. Of course, the possibility cannot be excluded that MW irradiation caused other undetectable membrane damage. Then, we used confocal laser scanning microscopy for the preservation check of the mitochondrial membrane for cytochemistry with MW‐irradiated fixation. The fluorescence of rhodamine 123 was observed in the inner spaces of the mitochondria at temperatures of 10° and 37°C. When the same tissues were fixed with 2% pFA using an MW processor as the sole fixative at 10°C, no mitochondrial fluorescence was observed. Cytochrome oxidase activity, by contrast, could be seen in the mitochondrial intermembrane‐intracristal spaces in the same condition. Formaldehyde is not the best aldehyde for the purpose of ultra‐structural preservation. On the other hand, light and electron microscopy showed that the endogenous peroxidase activity was localized in the nuclear envelope, endoplasmic reticulum, secretory granules, and Golgi apparatus of the hamster submandibular gland using 2% pFA‐0.5% PGA fixative with and without MW irradiations at temperatures of 10° and 37°C. Some of the same cells were fixed with only 2% pFA under MW irradiation at 10°C; however, marked diffuseness of the peroxidase activity was observed. Therefore, these results indicated that cytochrome oxidase activity was sensitive to heat with MW‐irradiated fixation. Peroxidase activity was very resistant to heat with MW‐irradiated fixation but not with pFA solo fixation, therefore, PGA had to be used.
Combined atomic force microscopy and scanning tunneling microscopy imaging of cross‐sectioned GaN light‐emitting diodes
Authors: Bender J. W. , Salmon M. E. , Russell P. E.
Published: June 2010

Cross‐sectional scanning tunneling microscopy (STM) was combined with atomic force microscopy (AFM) over the same area to characterize a cross‐sectioned GaN light emitting diode. Because GaN is typically grown on a non‐native substrate and also forms a wurtzite crystal structure, a cryogenic cleaving technique was developed to generate smooth surfaces. The depletion region surrounding the p‐n junction was clearly identified using STM. Furthermore, by imaging under multiple sample biases, distinctions between the n‐doped and p‐doped GaN could be made.
Spectra and lifetimes of fluorescence resonance energy transfer fluorophores under two‐photon excitation
Authors: Ashman Ross , Gu Min , Crimeen‐Irwin Blessing , Ludford‐Menting Mandy , Russell Sarah
Published: June 2010

We show two‐photon spectra and lifetimes acquired using conventional confocal microscopes equipped with an ultra‐short pulsed laser and a time‐gated intensified charge coupled device. We report on the two‐photon spectra and lifetimes of Alexa350, enhanced green fluorescent protein (EGFP), EGFP‐CD46, and Cy3 labelled antibodies. Cellular and extracellular EGFP two‐photon spectra and lifetimes are compared.