bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural characteristics of semipolar InN (112l) films grown on yttria stabilized zirconia substrates
Authors: Fujii Tomoaki , Kobayashi Atsushi , Ohta Jitsuo , Oshima Masaharu , Fujioka Hiroshi
Published: June 2010

We report on the growth of semipolar InN ($11\overline {2} l$) films on yttria stabilized zirconia (YSZ) substrates by pulsed laser deposition. We found that the growth orientation can be precisely controlled by utilizing the tendency for the epitaxial relationships of InN [0001] || YSZ [111] and InN [$11\overline {2} 0$] || YSZ [$1\overline {1} 0$] to be maintained. The full‐width at half‐maximum of the $11\overline {2} 6$ X‐ray rocking curves for an InN ($11\overline {2} 7$) film varies from 0.61 to 0.46° depending on the X‐ray angle of incidence.
Ab initio calculation of second harmonic generation in solids
Authors: Hübener Hannes , Luppi Eleonora , Véniard Valérie
Published: June 2010

An ab initio formalism for the calculation of macroscopic second order responses within the time dependent density functional theory (TDDFT) framework is presented. The linear Dyson‐like equation of TDDFT is generalized to second order and the resulting microscopic response is related to the macroscopic non‐linear susceptibility. The macroscopic relations are obtained considering Maxwell's equations and the non‐linear relation between the microscopic and macroscopic field. Some approximations have to be made to account for many body effects. The impact of the several levels of approximation on the second harmonic spectrum is illustrated for the example of bulk AlAs in the zincblende structure.
On the forcing of planetary‐scale Rossby waves by Antarctica
Authors: James I. N.
Published: June 2010

The propagation of Rossby waves forced at high latitudes into middle and low latitudes is studied using the barotropic vorticity equation on the sphere. Ray tracing theory indicates that fundamental differences exist between the response of an atmosphere initialized with typical northern hemisphere winter flow and typical southern hemisphere winter flow to such a forcing, with a substantial response more likely for the southern hemisphere case. Integrations with a fully nonlinear barotropic model confirm this suggestion and indicate that away from the local forcing region, linear theory provides a good description of the response. The most notable feature in the steady solutions is a split of the mid‐latitude jet close to New Zealand. The location of this split coincides well with a region where blocking is observed to be prevalent in the southern hemisphere.
Tropical forecasting at ECMWF: The influence of physical parametrization on the mean structure of forecasts and analyses
Authors: Tiedtke M. , Heckley W. A. , Slingo J.
Published: June 2010

The period 1984–1985 has seen a dramatic improvement in the quality of the ECMWF operational forecasts for tropical regions. This improvement is discussed in terms of the model changes during this period. Revisions include the introduction of a parametrization of shallow cumulus convection, modifications to the parametrization of deep cumulus convection, a new cloud scheme, and an increase in horizontal resolution with a change in spectral truncation from T63 to T106. Impact of the various model changes is assessed through a set of forecast experiments and through parallel 10‐day forecasts over a 20‐day period. The results show that the improvements in tropical forecasts are mainly through the reduction of systematic errors in response to a more realistic tropical diabatic forcing. The impact of these changes on the analyses is also assessed. This is shown to be substantial, particularly for the thermal state.
Atmospheric boundary‐layer structure over the Mediterranean during a Tramontane event
Authors: Flamant C. , Pelon J.
Published: June 2010

Observations of the unstable atmospheric boundary layer were made over the Mediterranean by the airborne backscatter lidar LEANDRE I during a cold air outbreak related to a Tramontane event. These measurements performed during the Pyrénées Experiment show a development of the internal boundary‐layer over the sea influenced by the atmospheric flow‐perturbation caused by the vicinity of the Pyrénées. A one‐dimensional model is used to analyse the internal boundary‐layer growth in relation with mixed‐layer temperature, specific humidity, surface fluxes and vertical velocity. It includes bulk formulae for surface‐flux determination taking into account surface and mixed‐layer values of these parameters. Transfer coefficient values are obtained which are smaller than those computed in the model of Stage and Businger (1981). Results obtained using nomograms of mean column‐heating computed by Chou and Atlas (1982) lead, in the case of the Pyrénées Experiment to overestimated surface‐fluxes. Comparison with our model reveals that the discrepancy originates from the higher heat‐transfer coefficient values used by Chou and Atlas. Model results are compared to lidar and in‐situ data (internal thermal boundary‐layer growth, temperature, specific humidity, average fluxes) and excellent agreement is obtained. The comparison between model results and lidar data shows that the growth rate of the internal thermal‐boundary‐layer is very sensitive to the vertical velocity w̄, which is not the case for surface fluxes. Comparisons between measured and modelled parameters thus allow the derivation of an estimation of the vertical‐velocity field in the vicinity of the Pyrénées. It is finally shown that a simplified equation could be used to estimate surface buoyant heat‐flux far from the shoreline during such cold air outbreaks provided accurate correction of vertical velocity impact on internal thermal‐boundary‐layer growth can be achieved.
Cross‐tropopause transport in the extratropical northern winter hemisphere, diagnosed from high‐resolution ECMWF data
Authors: Siegmund P. C. , van Velthoven P. F. J. , Kelder H.
Published: June 2010

The upward and downward mass fluxes of air across the tropopause, defined as the 3.5 potential vorticity unit (PVU) surface, are diagnosed for the extratropical northern hemisphere, using high spatial and temporal resolution (0.5° latitude and longitude, 31 levels, 3‐hourly) circulation data for January 1994 from the European Centre for Medium‐Range Weather Forecasts.

The diagnosed net cross‐tropopause transport is 0.35 × 1017 kg for January 1994 (downward) for the area north of 28°N. This net transport is smaller than that across the 2.5 and 1.5 PVU surfaces, and larger than the ‘downward control’ result. This indicates that the net downward transport across the tropopause is a combination of transport from the upper stratosphere to the troposphere, and transport from the lower stratosphere to the troposphere. The latter transport indicates the existence of a circulation in which air is transported from the subtropical upper troposphere to the upper troposphere at middle and higher latitudes via the lower stratosphere without ever reaching the upper stratosphere.

The diagnosed ‘local’ and ‘instantaneous’ cross‐tropopause fluxes (i.e. the fluxes at the smallest resolved scales) are, on average, about 40 times as large as their area and time‐mean values. This confirms the existence of a relatively large bidirectional exchange in the extratropics between the lower stratosphere and the troposphere.

The diagnosed local and instantaneous cross‐tropopause flux do not notably change if the horizontal and temporal resolution of the circulation data are decreased to 1° and 6 h. A further resolution decrease to 3.75° and 12 h, however, generally leads to quite different results for the local and instantaneous flux. The diagnosed zonal and monthly mean fluxes are not very sensitive to the latter resolution decrease, except at subpolar and subtropical latitudes. This small sensitivity in a large range of latitudes indicates that fluxes across the tropopause, which are quite concentrated on the small scales, are nonetheless irrelevant for the global mass budgets of the troposphere and the stratosphere.
Dual formulation of four‐dimensional variational assimilation
Authors: Courtier Philippe
Published: June 2010

A duality between two formulations of variational assimilation, three‐dimensionsal (3D‐Var) and the Physicalspace Statistical Analysis System (PSAS), is presented. It is shown that their conditioning is identical. the temporal extension of 3D‐Var leads to 4D‐Var. the temporal extension of PSAS, 4D‐PSAS, is achieved using an algorithm inspired by the representer technique but without the explicit computation of the representers. Assuming the model is perfect, both 4D‐Var and 4D‐PSAS are equivalent in terms of results produced and cost. Assuming the model is not perfect, the equivalence is preserved, but in 4D‐Var it is necessary to increase the size of the control variable while 4D‐PSAS remains almost unchanged. In duality, 4D‐Var remains almost unchanged by an increase in the number of observations used, whereas the size of the control variable in PSAS depends directly on this number.
A water balance modelling approach to optimising the use of water resources in ephemeral sand rivers
Authors: Love D. , van der Zaag P. , Uhlenbrook S. , Owen R. J. S.
Published: June 2010

Alluvial aquifers present a possibility for conjunctive use with surface reservoirs for the storage of water in ephemeral sand rivers such as the Mzingwane River in the Limpopo Basin, Zimbabwe. The Lower Mzingwane valley is a semi‐arid region with high water stress, where livelihoods have revolved around the large rivers for thousands of years. However, current water allocation favours the commercial user: of the 2600 ha irrigated in the 5960 km2 (596 000 ha) region, only 410 ha are for smallholder farmers. A water balance approach was used to model the surface water resources and groundwater resources to determine the potential for expanding irrigation and to explore water allocation options. Using a combination of field and laboratory investigations, remote sensing and existing data, the Lower Mzingwane valley was modelled successfully using the spreadsheet‐based model WAFLEX, with a new module incorporated to compute the water balance of alluvial aquifer blocks.

Results showed that the Lower Mzingwane alluvial aquifers can store 38 × 106 m3 of water, most of that storage being beyond the reach of evaporation. Current water usage can be more than tripled: the catchment could supply water for currently‐planned irrigation schemes (an additional 1250 ha), and the further irrigation of two strips of land along each bank of the Mzingwane River (an extra 3630 ha)—without construction of any new reservoirs. The system of irrigating strips of land along each bank of the Mzingwane River would be decentralized, farmer or family owned and operated and the benefits would have the potential to reach a much larger proportion of the population than is currently served. However, there could be substantial downstream impact, with around nearly one‐third of inflows not being released to the Limpopo River.

The approach developed in this paper can be applied to evaluate the potential of alluvial aquifers, which are widespread in many parts of semi‐arid Africa, for providing distributed access to shallow groundwater in an efficient way. This can enhance local livelihoods and regional food security. Copyright © 2010 John Wiley & Sons, Ltd.
Fractal behavior of electron trajectories and spatial distributions of secondary electron birth sites in solids
Authors: Li H. , Ding Z.‐J. , Wu Z. Q.
Published: June 2010

The fractal behavior of electron scattering in solids, simulated by the Monte Carlo method, has been studied. The trajectories of electrons of 1–10 keV primary energies in Si, Cu, Ag, and Au have been simulated. The Hausdorff dimensions of trajectories of primary electrons, trajectories of primary electrons plus secondary electrons, and spatial distributions of secondary electron birth sites have been determined by the box‐counting method. The fractal geometry can be used to describe quantitatively the complexity of the electron scattering process in solids.
Quantitative three‐dimensional confocal imaging of the cornea in situ and in vivo: System design and calibration
Authors: Petroll W. Matthew , Jester James V. , Cavanagh H. Dwight
Published: June 2010

A new depth encoding system (DES) is presented, which makes it possible to calculate, display, and record the z‐axis position continuously during in vivo imaging using tandem scanning confocal microscopy (TSCM). In order to verify the accuracy of the DES for calculating the position of the focal plane in the cornea both in vitro and in vivo, we compared TSCM measurements of corneal thickness to measurements made using an ultrasonic pachymeter (UP, a standard clinical instrument) in both enucleated rabbit, cat, and human eyes (n = 15), and in human patients (n = 7). Very close agreement was found between the UP and TSCM measurements in enucleated eyes; the mean percent difference was 0.50 ± 2.58% (mean ± SD, not significant). A significant correlation (R=0.995, n=15, p< 0.01) was found between UP and TSCM measurements. These results verify that the theoretical equation for calculating focal depth provided by the TSCM manufacturer is accurate for corneal imaging. Similarly, close agreement was found between the in vivo UP and TSCM measurements; the mean percent difference was 1.67 ± 1.38% (not significant), confirming that z‐axis drift can be minimized with proper applanation of the objective. These results confirm the accuracy of the DES for imaging of the cornea both ex vivo and in vivo. This system should be of great utility for applications where quantitation of the three‐dimensional location of cellular structures is needed.
The structure difference of proteins isolated on substrate with different techniques as studied by the atomic force microscope
Authors: Umemura K. , Sutoh K. , Tokunaga F. , Kataoka M. , Kamkubo H. , Arakawa H. , Ikai A.
Published: June 2010

The height and width of proteins deposited on mica substrates were measured from cross sections of their atomic force microscope (AFM) images. The tapping mode AFM gave very stable and reproducible images for high molecular weight proteins. The following results were obtained: (1) The thickness of mono‐, bi‐, and trilayered purple membranes was 5.3, 10.4, and 16.0 nm, respectively. The calibration curve of z range of AFM based on the above data was linear. The deviation of the calibration curve at the origin was < 0.6 nm. (2) The height of slow form α‐2‐macroglobulin (α2M) molecule changed depending on sampling methods. When the protein was freeze‐dried on a mica substrate prewetted with water, α2M gave the highest value for its height. The fact that freeze‐drying, especially after prewetting of the substrate, was effective to prevent flattening of the molecule suggested that sample deposition must be as gentle as possible to keep the original height of the molecules. (3) Furthermore, we compared differences of height and width between α2M and myosin filament. The result suggested that α2M had a disk‐like rather than a spherical form. Large proteins such as α2M are still difficult to crystallize for x‐ray analysis, and we tested the AFM method for the study of minute height differences of such proteins.
A nondestructive method for three‐dimensional reconstruction of luminescence materials: Principles, data acquisition, image processing
Authors: Saparin G. V. , Obyden S. K. , Ivannikov P. V.
Published: June 2010

In the study presented here we have tried to state the principles and calculate and visualize models of three‐dimensional (3‐D)‐cathodoluminescence reconstruction of luminescence structures by scanning electron microscopy (SEM). The new technique does not destroy the specimen and uses the variable energy of the electron beam to penetrate to different depths in the specimen volume. The SEM in color cathodoluminescence mode (CCL‐SEM) detects integrated panchromatic CL‐images for different energies of the electron beam. The use of electron scattering theory in solids and theories of cathodoluminescence and color allow the production of problem‐oriented software for the routine processing of primary images. Processed images represent the CCL‐SEM displays of separated layers (without CL information from other layers) up to the maximum depth penetrated by the beam. The 3‐D reconstruction is carried out through algorithms developed using a personal computer, software, and a set of processed two‐dimensional (2‐D) images. The first experimental work was accomplished using a multilayer SiC mesastructure. The final reconstructed image of SiC material demonstrates separated epitaxial layers of different SiC polytypes and Z sections (YOZ and XOZ sections). The 3‐D image represents the space distribution of CL‐spectral data in color CL interpretation.
Multislice simulation of high‐resolution scanning transmission electron microscopy Z‐contrast images of semiconductor heterointerfaces
Authors: Bollig B. , Fischer H.‐G. , Kubalek E.
Published: June 2010

Multislice simulations of high‐resolution scanning transmission electron microscopy (STEM) Z‐contrast images have been used to investigate semiconductor heterointerfaces between ternary and binary semiconductors. As an example, the ZnSSe/ZnSe material system, which is of great interest for the development of blue semiconductor lasers, has been chosen. Two different models for the description of ternary semiconductors are compared, the thickness dependence and composition dependence of Z contrast are investigated, and the visibility of important interface structures in Z‐contrast micrographs is discussed. By comparison with experimental high resolution (∼ 0.21 nm) Z‐contrast micrographs, it is demonstrated how image simulation can facilitate the interpretation of experimental Z‐contrast micrographs.
Monte Carlo simulation of scanning electron microscope signals for lithographic metrology
Authors: Lowney Jeremiah R.
Published: June 2010

Two computer codes for simulating the backscattered, transmitted, and secondary‐electron signals from targets in a scanning electron microscope are described. The first code, MONSEL‐II, has a model target consisting of three parallel lines on a three‐layer substrate, while the second, MONSEL‐III, has a model target consisting of a two‐by‐two array of finite lines on a three‐layer substrate. Elastic electron scattering is determined by published fits to the Mott cross section. Both plasmon‐generated electrons and ionized valence electrons are included in the secondary production. An adjustable quantity, called the residual energy loss rate, is added to the formula of Joy and Luo to obtain the measured secondary yield. The codes show the effects of signal enhancement due to edge transmission, known as blooming, as well as signal reduction due to neighboring lines, known as the “black‐hole” effect.
Scanning reflection electron microscopy of surface topography by diffusely scattered electrons in the scanning electron microscope
Authors: Baba‐Kishi K. Z.
Published: June 2010

In this paper, the technique of scanning reflection electron microscopy (SREM) by diffusely scattered electrons in the scanning electron microscope is described in detail. A qualitative account of the formation of image contrast in SREM is also described. It is assumed that, for grazing geometry, forward‐scattered electrons reflect from regions close to the surface, following a few scattering events within the first few atomic layers, and lose very little energy in the process. The penetration depth of the primary electrons is very limited, resulting in strongly peaked envelopes of forward‐scattered electrons. It is also assumed that a surface containing topographic features presents a range of tilt angles, resulting in different reflection coefficients. Tilt contrast results because each facet has a different scattering yield, which is dependent upon local surface inclination. Full details of the instrumentation designed for SREM are described, and to illustrate the technique, results recorded from an epitaxial GaAs on GaAs crystal, Pb2(Zr,Ta)O6 thin film on silicon, and SiO2 amorphous film on silicon are presented.
A natural color scanning electron microscopy image
Authors: Oho Eisaku , Ogashiwa Tkeshi
Published: June 2010

A method for obtaining a scanning electron microscopy (SEM) image with natural color information (NCSEM image) has been developed by using an SEM operated under low vacuum or low voltage, a video microscope (VM), and a high‐performance personal computer. In order to produce an NCSEM image with both the fine structures of the SEM image and the color information included in the VM image, an improvement of the depth of focus in VM image is required. This can be successfully performed by some digital image processing techniques. A difference in resolution between the SEM image and the VM image does not disturb our study as shown in the text. In addition, the well‐known hue, saturation, intensity (HSI) color model, which is frequently utilized for color image manipulation, was originally altered for the present purpose.
Optimizing AC‐mode atomic force microscope imaging
Authors: Ho Huddee , West Paul
Published: June 2010

We have operated an atomic force microscope in ambient air with several oscillating cantilever modes to establish the optimal scanning parameters to maximize image resolution and to minimize probe and sample damage. This was done by scanning a surface in air and correlating scan parameters such as oscillation amplitude and damping with image resolution. We also examined the geometry of the probe with a scanning electron microscope, before and after scanning, in order to determine whether the scanning technique had an effect on the geometry of the probe tip. If the probe is oscillated such that it contacts the surface on each oscillation, substantial damage or “wear” to the probe occurs and significant degradation of image quality was observed. In ambient air, the optimal conditions are achieved when the probe penetrates the contamination layer and reverses direction before touching the surface. Under these “near‐contact” conditions no probe damage is observed and high‐image resolution can be maintained indefinitely.
In vivo confocal microscopy of human skin: A new design for cosmetology and dermatology
Authors: Corcuff P. , Gonnord G. , Piérard G. E. , Lévěque J. L.
Published: June 2010

In‐depth exploration of cellular structures in living human skin in situ is possible with the tandem scanning microscope (TSM). However, the rigid design of the microscope limited observations to the arms, hands, and fingers. A mobile version allowing the investigation of any parts of the body has been designed. The head containing the Nipkow disk and the optical path were the only part saved from the original TSM. This prototype can be used to observe, in real time, the different skin structures down to a depth of 200 μm and to measure the thickness of the different layers with micron precision level. The hydration of the stratum corneum (SC) could be assessed. For example, lengthy immersion of the hand in water led to an increase in SC thickness without affecting that of the living epidermis. Occlusive patch tests also showed that water and, even more so, propylene glycol, led to transient swelling of the SC. In dermatology, the example of psoriasis illustrated the value of the TSM for describing, measuring, and assessing pathologic skin changes. The availability of this noninvasive method for observing changes with time in a given skin site should prove useful for monitoring treatment efficacy. This tool opens up new insight for the investigation of cutaneous pathophysiology.
Enhanced scanning control in a confocal scanning laser microscope
Authors: Trepte Oliver
Published: June 2010

A fast and flexible scanning unit, allowing scanning rates of more than 1 kHz over regions identified in a specimen, has been developed and evaluated. This scanning unit replaces the original scanning unit in the Phoibos confocal scanning laser microscope and features full backward compatibility, while at the same time allowing fast and flexible scanning modes, such as point scanning, line scanning, and scanning along user‐selected closed curves. The scanning unit uses two galvanometer‐mounted mirrors for scanning. A standard procedure for recordings with this scanning unit would be to scan an overview image with conventional raster scanning to identify a region of interest, mark a point, a line, or a closed curve over this region, and to start the scanner. An iterating algorithm then calculates the waveforms needed by the scanner to follow the identified curves with pixel precision. With this scanning unit and its controlling software, experiments demanding time‐resolved recordings within the millisecond range can be performed. Repetition rates up to >1 kHz for line scanning and curve scanning, and >100 kHz for point scanning are obtainable. This allows time‐resolved studies of fast reactions in living tissue to be performed with the spatial resolution and signal‐to‐noise ratio obtainable with a point scanning confocal microscope.
Secondary electron imaging in the variable pressure scanning electron microscope
Authors: Mohan A. , Khanna N. , Hwu J. , Joy D. C.
Published: June 2010

Secondary electron imaging is not possible in the variable pressure scanning electron microscope because the mean free path of the secondaries in the gas is too short to permit them to reach the detector. This paper therefore investigates an alternative strategy for producing an image containing significant amounts of secondary electron contrast. This involves modifying the microscope by the addition of a biased electrode above the sample and then collecting a specimen current signal. This system, originally described by Farley and Shah (1988), is found to produce true secondary electron detail over a wide range of conditions.
The variogram method for characterization of scanning electron microscopy images
Authors: Bonetto R. D. , Ladaga J. L.
Published: June 2010

Some aspects of the variogram method used for characterizing the surface texture through scanning electron microscopy images are discussed. The sample case, which presents periodicity in some scale, is extensively discussed. The variogram application is studied for characterizing also the region in which the information attainment about the fractal dimension is obstructed by the presence of the minimum in the variogram due to the above‐mentioned periodicity. The use of an invariant parameter at rotations is proposed to characterize the surface texture in such a region.
In vivo spatio‐temporal visualization of the human skin by real‐time confocal microscopy
Authors: Bertrand C. , Corcuff P.
Published: June 2010

A modified tandem scanning confocal microscope is used to obtain in vivo images of the human skin in real time. Three‐dimensional and temporal visualizations are demonstrated with volume reconstruction and blood flow images. Two image processing methods based on Fourier transform and logarithmic processing are presented. Their applications in noise removal of the scanning disk lines and of the heterogeneity of light are illustrated.
Laser and tandem scanning confocal microscopic studies of rabbit corneal wound healing
Authors: Ichijima Hideji , Jester James V. , Petroll W. Matthew , Cavanagh H. Dwight
Published: June 2010

The process of corneal endothelial wound healing was studied using laser and tandem scanning confocal microscopy (LSCM and TSCM). Following transcorneal freeze (TCF) injury, rabbit corneas were observed using ex vivo LSCM and in vivo TSCM. LSCM revealed the intracellular actin filament organization which, stained with phalloidin‐FITC, in migrating endothelial cells, transformed fibroblast‐like cells, stroma keratocytes, and epithelial cells during wound healing in corneal tissue. The TSCM provided sequential spatial observation of morphologic changes from endothelium to epithelium of the cornea during in vivo cellular repair of wound healing noninvasively on the same cornea without animal sacrifice. Ex vivo LSCM supported the morphologic analysis of the in vivo TSCM observations.
Observations of human corneal epithelium by tandem scanning confocal microscope
Authors: Tomii Satoshi , Kinoshita Shigeru
Published: June 2010

We applied the tandem scanning confocal microscope (TSCM) to 30 healthy human corneas of 3 normal volunteers and 27 patients with cataract and retinal detachment to observe normal corneal epithelial cells in vivo. All corneas were normal under slit lamp microscopic examination. The superficial and basal epithelial cells close to the basal lamina in the central cornea were recorded on videotape and analyzed by a computer‐assisted digitizer. The mean cell areas of superficial cells exposed at the surface and basal cells at the horizontal section were 624 ± 109 μm2 and 66 ± 5 μm2, respectively. The ratio of superficial to basal mean cell area was 11.0 ± 4.5. TSCM was thus useful in evaluating the relationship between superficial and basal cells in human corneal epithelium in vivo.
The scanning optical microscope (Extracts on near‐field microscopy)—from a 1975 report
Authors: Kompfner R. , Sheppard C. J. R. , Walsh D. , Choudhury A. , Gannaway J. N. , Hale P. G.
Published: June 2010

The following consists of extracts concerning near‐field microscopy from a Progress Report prepared in April 1975 as Oxford University Engineering Laboratory Report No. 1883/77, describing work initiated by the late Professor R. Kompfner. Preliminary experimental work on near‐field microscopy is outlined, and a theory for contrast formation is presented.
Surface plasmon and guided optical wave microscopies
Authors: Aust E. F. , Sawodny M. , Ito S. , Knoll W.
Published: June 2010

This article summarizes some recent developments in the field of surface plasmon and guided optical wave microscopies. It is shown that these imaging techniques based on evanescent light allow for a quantitative optical characterization of ultrathin films with a thickness sensitivity of a few Ångstroms and a lateral resolution of μm.
Highly controllable fabrication of fiber probe for photon scanning tunneling microscope
Authors: Pangaribuan Togar , Jiang Shudong , Ohtsu Motoichi
Published: June 2010

A selective chemical etching was used to fabricate fiber probes for the photon scanning tunneling microscope (PSTM). The cladding diameter of the fiber probe was controlled by varying the first‐step etching time. The cone angle of the fiber probe tip was controlled by varying the doping ratio of the fiber and the composition of the etching solution. A cladding diameter of 8 μm and a tip diameter of about 3 nm were fabricated. The smallest cone angle was 14°.
Evanescent‐field scanning microscope with fourier‐transform infrared spectrometer
Authors: Nakano T. , Kawata S.
Published: June 2010

An evanescent‐field scanning microscope for infrared microanalysis has been developed. This microscope uses an evanescent field produced by total internal reflection with a high refractive index prism to attain a high spatial resolution, better than the wavelength. This microscope was combined with a Fourier‐transform spectrometer. The principle of the method and experimental results for edge detection at different absorption wavelengths are described.
Development of laser scanning microscopy using a near ultraviolet laser
Authors: Kashima Shingo
Published: June 2010

We have developed a legitimate fluorescence con‐focal scanning microscope (CLSM) using a near ultraviolet (UV) laser. This system has almost no chromatic aberration from the near UV region to the visible region (350–600 nm), and the objectives are designed as water‐immersion type. Therefore this system provides the high‐quality fluorescence image excited by the near UV laser, and high‐quality image of deep points in a sample.
A comparison of techniques and images obtained using SEAM and SPAM
Authors: Severac H. , Marty‐Dessus D. , Franceschi J.‐L.
Published: June 2010

Images of a circuit have been obtained with similar techniques. Using two scanning acoustic microscopes—a SEAM (scanning electron acoustic microscope) and a SPAM (scanning photoacoustic microscope)—an examination of the surface and subsurface images has shown varied details while highlighting the differences between the above techniques. This paper presents in the first instance the experimental arrangements with the recorded results, followed by a comparison between them.
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

The 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

The 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

A 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

We 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

An 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.
Scanning electron microscopy 1928–1965
Authors: McMullan D.
Published: June 2010

This article gives an account of the origins of the scanning electron microscope (SEM) and traces its development up to 1965 when the first SEM was marketed by the Cambridge Instrument Company. The survey concentrates on the SEM, as distinct from the microanalytic electron probe instruments that were also being developed during this period.
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

Digital 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

Quantitative 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

To 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

A 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

Limitations 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

X‐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

This 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

A 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

Spurious 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.