bluuebunny/crossref_metadata_2025_split huggingface dataset:
Magnetic einzel lens satisfying anastigmatic and achromatic conditions
Authors: Baba Norio , Nagashima Keiji , Kanaya Koichi 
Published: June 2020

Starting from the rigorous treatment on a magnetic einzel lens given by the field distribution along the optical axis z; H(z)= Ho (z/a)m-1/ [1+(z/a)2m], where m is the parameter depending on the double gap pole- piece geometry and the magnetic flux concentration, the lens model is the simple einzel lens whose solution of paraxial ray paths can be obtained in the hypergeometric function. For m=2, it corresponds to the permanent einzel lens introduced by Lenz(1956).Based on this solution, the important optical quantities and third order aberrations for the practical lens representing the true field distribution which is classified by m=3, as shown in Fig.1, are analytically formulated.Anastigmatic and achromatic lenses satisfying the anastigmatic and achromatic conditions are presented at the view-point of lens design.1] Field distribution and paraxial ray paths The paraxial differential equation for a magnetic field of rotational symmetry is, u"+K2u=0; K=Kof(z/a), and Ko2=(e/m)Ho2/(8)Φ (1), where Ho is the maximum value of the field,(e/m) the specific charge of the electron, Φ the accelerating potential and f(z/a) expresses the function of the field distribution along the axis z/a.
An objective lens for an electron microscope with compensated axial chromatic aberration
Authors: Koops H. , Bernhard W. 
Published: June 2020

The resolving power of transmission microscopes is limited by diffraction and by spherical and chromatic aberrations of the objective lens.To compensate the axial chromatic aberration, electric quadrupole fields may be used (1,2). We therefore combined a condenser-objective lens of 2 mm focal length with an electron-optical aplanator (3). Earlier experiments showed that the axial chromatic aberration of the aplanator can be compensated by counteracting electric and magnetic quadrupole fields (4,5). High values of these correcting fields yield a negative chromatic error of the aplanator. It compensates the positive chromatic aberration coefficient of 1.5 mm of the objective lens.The specimen is situated near the middle plane of the condenser-objective lens. This lens produces a 60-fold magnified virtual image in a plane 122 mm above the specimen. The aplanator transfers this image 1:1 into the object plane of the intermediate lens and compensates the aberrations (6).Figure 1 shows a micrograph of a resolution test specimen.
On-line electron-optical correlation computing in the CTEM
Authors: Guckenberger R. , Hoppe W. 
Published: June 2020

Light diffractograms of electron micrographs are frequently used to study the transfer function of the microscope. In order to utilize diffractograms for control operations in the microscope, several attempts have been undertaken to obtain on-line diffractograms /1 - 3/. Alternatively correlation functions (CF) may be used /4-8/. In this paper we describe an electron-optical device for the computation of such CF and its on-line operation in a microscope.The auto-correlation function (ACF) is the inverse Fourier transform of the squared modulus of the Fourier transform (diffractogram) of an image. Therefore it also contains the transfer function. It is its zero peak (main peak) which is of particular interest. In noisy images the main ACF-peak of the noise contributes in an unwanted way to the main ACF-peak of the image. This can be avoided if the ACF will be computed of two images which are identical except for noise /9/ (noise-reduced ACF= NRACF).
A digital storage and processing system which permits aposteriqri image accumulation
Authors: Rust H.-P. , Krahl D. , Herrmann K.-H. 
Published: June 2020

The investigation of radiation-sensitive specimens at minimum exposure conditions requires an image-recording system of high DQE which allows immediate observation and processing of the image even at small electron doses. The TV image intensifier, connected to a digital storage unit which counts single electron events, has proved suitable [1]. Since the compromise between signal-to-noise ratio and radiation damage cannot be anticipated due to the statistic character of the damage, it is advisable to store a sequence of very slightly exposed single images in order to carry out subsequent accumulations which can be repeated and optimized. For this purpose a video recorder has been applied [2,3] which records a sequence of single frames. In the following, a system is presented which is not only optimal for the above mentioned purpose but which can also be used for the registration of other dynamic processes.The single electron video signals which are supplied by the intensifier chain are digitized and normalized -- with regard to spatial and temporal multiple counting -- by a signal processor (Fig. 1).
Simplified vacuum system for routine transmission electron microscopes
Authors: Egle W. , Guetter E. 
Published: June 2020

The outstanding features of the new ZEISS transmission electron microscope are a vacuum system (ion getter pump with rotary pump) which is not standard in a high-performance, middle-class instrument, and its compatibility with a new external photographic system. The external photography facility which is described in a separate paper, is superior to the normal documentation systems in that it does not load the vacuum system. The evacuated interior of the instrument does not come into contact with gassing photographic material.These characteristics of external photography, intended primarily for routine work with high photographic workload, make the concept of a simplified vacuum system for electron microscopes, with a fore-vacuum pump only, most attractive. The results of investigations dealing with such a simplified, low-cost vacuum system are described below.Fig. 1 shows the examined version of the vacuum system mounted on the new TEM. It consists of a two-stage, 8 m3/h rotary pump with baking adsorption trap, vacuum measuring point and two electromagnetic valves.
Topographical measurements at grazing incidence on the SEM
Authors: Reisner J. H. , Johnston L. B. 
Published: June 2020

The SEM used at grazing incidence for topographical measurement of small surface detail has been the quantitative basis for studies of signal depth and wave shape in the development of the RCA SelectaVision VideoDisc. Signal amplitudes as small as 150 Å are encountered and measured with a probable error of 50 Å (Figures 3, 4).The method is described by R. A. Hoover [1]. It exploits a Y/X scan length ratio considerably less than unity to increase the magnification and resolution in the Y (vertical) direction without sacrificing field in the X (horizontal) direction. It further establishes a direction along which the surface contour is to be measured by using the X scan of the electron beam to deposit a line of contamination on the specimen surface.
New STEM spectroscopic techniques for simultaneous electronic analysis and observation of defects in semiconductor materials and devices
Authors: Petroff P.M. , Lang D.V. , Strudel J.L. , Savage A. 
Published: June 2020

The main interest in the study of defects in semiconductor materials lies in their electronic properties and their effects on the device characteristics. Conventional transmission electron microscopy (CTEM) and scanning transmission electron microscopy (STEM) provide the tools for analyzing the crystallographic nature of defects in these materials. However, until now, there have been no techniques which allow for the simultaneous observation of a defect along with an analysis of its electronic properties, e.g., energy level, radiative and nonradiative behavior. We have developed on a STEM unit several techniques which permit displaying and analyzing the spatial distribution of nonradiative and/or radiative recombination centers in a thin semiconductor sample which may be simultaneously analyzed by STEM and CTEM.The first technique uses the electron beam induced current (EBIC) in the thin sample which contains a p-n junction or a Schottky barrier. The surface recombination effects have been minimized to allow for high contrast EBIC images of the recombination centers in the material.
Misfit dislocations in heteroepitaxial systems with low dislocation density
Authors: Hagen W. , Strunk H. 
Published: June 2020

The growth of heteroepitaxial layers causes stress across the interface which in a certain range of layer thickness may he relaxed by the formation of misfit dislocations at the interface. Systematic investigations of such misfit structures by transmission electron microscopy (TEM) have previously heen conducted only on systems with a relatively large misfit parameter f, i.e. with a high dislocation density. However, this case presents difficulties in the analysis because of the complexity of the dense structures.Interfaces containing a low density of misfit dislocations, e.g. heteroepitaxial systems with low misfit, should consequently be investigated. High voltage electron microscopy (HVEM) enables us to study specimens of several μm in thickness and offers decisive advantages over 100 kV TEM: i) generally, specimens can he prepared by thinning the substrate only, ii) thick foils are mechanically stable, which allows the preparation of specimens with an electron transparent area of several mm2.We report here new results on the initial formation of misfit dislocation structures in the heteroepitaxial system Ge on GaAs (f = 0.074%).
Study of ferroelectric domains on G.A.S.H. single crystals by the scanning electron microscope
Authors: Le Bihan R. , Jouet G. 
Published: June 2020

The ferroelectric properties of guanidine aluminium sulphate hexahydrate (G.A.S.H.) were discovered in 1955 (1). The polar axis was found to be perpendicular to the natural cleavage plane. The domain structure of G.A.S.H. have been observed by Pearson and Feldman (2) by pulver technique, Yuri at al. (3) by electroluminescence and B. Hilczer at al. (4-5) by electron microscope decoration techniqueWe study domain structure in G.A.S.H. single crystals whithout metallization with a scanning electron microscope (S.E.M.). Figure 1 shows the observations obtained on a no etched crystal observed with a scanning electron microscope in the secondary electron emission mode; we see a domain. When the accelerating voltage Vacc of the incident beam pass from 2.3 KV. to 5 KV. the contrast between domains is inversed. At 3.5 KV. the contrast is the same that at 5 KV. but the domain wall is more precise. The inversion of contrast is obtained between 3.3 KV. and 3.4 KV. ; and in this inversion zone we have not any contrast due to the domain or to its boundary.
Temperature dependence of ECP contrast: independent or dependent Bloch wave model?
Authors: Kohl H.-J. 
Published: June 2020

The temperature dependence of the ECP contrast of thick Si, Cu, Ag, Au crystals has been investigated with the rocking crystal method /1,2,3/. The ECP is written into a storage unit. The contrast measurements could be performed by writing linescans of the ECP signal on an x-y recorder at a specimen temperature of 500 K and at room temperature. The results obtained with silicon and silver (fig. 2) show a decrease of contrast c with increasing value g of the reciprocal lattice vector belonging to the investigated band edge (c=(IBmax-IBmin)/(IBmax+IBmin), IB: intensity of the backscattered electrons).With the two beam case of the dynamical theory the temperature dependence of the ECP contrast could be calculated. The contrast is produced by a modulation of the Bloch wave field in the crystal. If absorption is ignored the modulation does not change with depth in the independent Bloch wave model, but in the dependent Bloch wave model it is developing with depth due to the interference between the Bloch waves.
The energy dependence of diffusion model for an electron probe into solid targets
Authors: Kanaya Koichi , Ono Susumu 
Published: June 2020

The penetration and energy loss characteristics of an electron probe with energies 1 and 103 KeV in solid targets are obtained by using the potential function as V(r)=(Ze2/a)(r/a)(l/n)-2exp(-r/a) with the screening radius a=0.77aHZ-1/6 [Å], where e is the electronic charge, Z the atomic number, aH the Bohr radius of hydrogen, and n indicates the degree of screening ( n goes 1 ∼ ∞ as the incident energy E∘ decreases and is determined based on the empirical basis1)).Then, combining the diffusion effect due to multiple collision) and the energy retardation in accordance with E/E∘=(1-y)n/(l+n), with the scattering cross section σ in the Lenard absorption law of ηT=exp(-Nσx), consistent expressions are obtained for the transmission ηT, backscattering fraction ηB with the reduced depth y=x/R and the maximum energy loss depth yE, normalized by the penetration range R as a function of the parameter γ which is derived as functions of the incident energy E∘ and the atomic number Z.
Application of the monte carlo method to high energy electron scattering (0.3-1.5 MeV)
Authors: Soum G. , Arnal F. , Balladore J.L. , Jouffrey B. , Verdier P. 
Published: June 2020

Techniques for using the Monte-Carlo method for studying electron scattering in solids have been developed by several authors (1). The method is used to determine the angular distribution of electrons emerging from amorphous or polycrystalline specimens ; the total transmission and backscattering coefficients can also be obtained.- Method of calculation -Let Iθ be the intensity scattered in the direction making an angle θ with the incident electrons ; thus Iθ represents the number of electrons scattered in this direction within a solid angle Δw = πα2, where α is the semi-angle of the collector as seen from the specimen. For a specimen of thickness x, the angular distribution function may be written:I∘ denotes the intensity of the incident monoenergetic electron beam, Tα the transmission coefficient along the direction of incidence for a semi-angular aperture α and TθN the normalized transmission coefficient in the direction θ
Thickness determination of thin films by electron backscattering: principles, problems, and applications
Authors: Niedrig H. 
Published: June 2020

For thin films with thicknesses D ≪ R/2 (R: range of primary electrons within the film material) the total electron backscattering ratio η = Ir/IO proved to be proportional to λ4NAZ2D for mean and high atomic numbers Z (λ: electron wavelength, NA: atomic number density), from which a thickness determination method has been developed.The observed high values of the backscattering ratio can only be explained by assuming multiple scattering starting very rapidly at thicknesses of about 10 nm even at low atomic numbers thus increasing the backscattered intensity from single scattering events (fig. 1) and by using the Mott scattering cross-section for high atomic numbers (fig. 2). For very thin films of low atomic numbers single Rutherford scattering seems to be applicable.By focusing the electron beam into the film plane and scanning the beam across the film the thickness distribution of self-supporting crystalline films can be determined.
A new image processing software system for structural analysis and contrast enhancement
Authors: Frank Joachim , Shimkin Brian 
Published: June 2020

We report on the development of a new image processing software system SPIDER (System for Processing of Image Data in Electron Microscopy and Related Fields). The need for a user-oriented software system for electron image processing has been previously recognized /1-4/. These systems have in common that they allow users with a minimum amount of computer experience to define complex operations on images.The present system runs under the PDP 11/45 RSX-11D (Digital Equipment Corp.) executive in a multi-user, multi-task environment. Image enhancement of large images (e.g., box convolution and point mapping operations) as well as structural electron microscopy (Fourier operations, 3-d reconstruction) had to be accommodated. Characteristic for the electron microscope application is the need to process series of images closely related to each other (defocus, tilting, and averaging series).In SPIDER, the images are read and transferred by magnetic tape from the microdensitometer to PDP 11 disk files.
Molecular images of phthalocyanines and hydrocarbons
Authors: Fryer J.R. 
Published: June 2020

Reported efforts to obtain molecular images have hitherto been confined to chlorinated copper phthalocyanine that is atypical in having a high thermal and radiation stability. The radiation limited resolution of molecules has been described by the minimum resolvable object sizeC being object contrastf electron utilisation factorNcrcritical exposure for specimen destructionThe normal value used for C is approximately 0.1 but since this is the parameter most ameanable to improvement, efforts to increase C were made These efforts included the use of a high resolution objective lens of Cs = 0.67mm so that the constant phase contrast transfer envelope extended down to 3Å at the Scherzer defocus, and a 20μm condenser aperture Minimal exposure techniques were used with Ilford X-ray film to overcome the difficulties of low beam intensity and mechanical vibration of the specimen.Our previous studies on α' copper phthalocyanine(2) had required the specimen to be tilted for molecular superimposition on the unit cell b axis, A survey of a variety of hydrocarbons revealed that structures of planar molecules where the molecular plane makes an angle of greater than 40° to the b axis, tend to grow on KC1 with the b axis normal to substrate - i,e. no tilting is required to image a column of superimposed molecules.
Transmission electron microscopy analyses of complex ceramics
Authors: Shaw T. 
Published: June 2020

Many potentially useful ceramic materials have complex structures which are difficult to determine using x-ray analysis alone. By the use of contemporary transmission electron microscopy-techniques such as lattice fringe imaging and contrast experiments much information can be obtained about such structures greatly simplifying structure determination. It has already been demonstrated that images of “open” structures bearing a one to one correspondence with the projected structure can be obtained. However, in many commercially important ceramics atoms or atom concentrations are two closely spaced to be resolved directly by current microscopes. In this presentation examples are shown of the type of structural information that is obtainable from such “close packed” structures using transmission electron microscopy, two examples being given below.In Fig. 1(a) a two dimensional fringe image of a region of a 15 R polytype from the Be-Si-N system is shown on the left. It can be seen from this image that the structure is made up of three identical blocks of five close packed planes each related by a translation of 1/3[100] giving a repeat stacking in the close packed [001] direction of fifteen close packed layers.
Theoretical investigation of superlattice-fringe images of ordered alloys
Authors: Allen Samuel M. 
Published: June 2020

A computer simulation of lattice-fringe imaging of ordered Fe-Al and Cu-Au alloys has been carried out, using multiple-beam dynamical diffraction theory. This study corrects and extends results presented earlier for an Fe-Al alloy and provides additional results to those of Sinclair et al. for Cu3Au.Systematic-row calculations were carried out in which eight or nine beams were excited, depending on whether two or three beams, respectively, were allowed to contribute to the image. The computed parameters of the dynamical theory (Bloch wave amplitudes and vectors) were used to compute superlattice-fringe images, taking into account the effects of lens aberrations as described by Sinclair et al. (4). Four different diffraction geometries (imaging modes) were employed in the study, as indicated in Figure 1 (Only the beams allowed to contribute to the image are shown.).
7-beam lattice images of (110) oriented Ge
Authors: Parsons J.R. , Hoelke C.W. 
Published: June 2020

The direct imaging of a crystal lattice has intrigued electron microscopists for many years. What is of interest, of course, is the way in which defects perturb their atomic regularity. There are problems, however, when one wishes to relate aperiodic image features to structural aspects of crystalline defects. If the defect is inclined to the foil plane and if, as is the case with present 100 kV transmission electron microscopes, the objective lens is not perfect, then terminating fringes and fringe bending seen in the image cannot be related in a simple way to lattice plane geometry in the specimen (1).The purpose of the present work was to devise an experimental test which could be used to confirm, or not, the existence of a one-to-one correspondence between lattice image and specimen structure over the desired range of specimen spacings. Through a study of computed images the following test emerged.
The study of defects in Sb2S3 by method of direct lattice resolution
Authors: Kosevich V.M. , Sokol A.A. , Bagmut A.G. 
Published: June 2020

1.Sb2S3 has the orthorombic lattice with a=11,23;b=11,31; c=3,84 Å. Its crystal structure is constructed of the double ribbons of antimony and sulphur atoms,parallel to [00l].Vacuum deposited films of Sb2S3 re amorphous{they were crystallyzed in spherolite mode by the electronbeam heating.The study of defect structure of the Sb2S3 spherolite crystals by method of direct lattice resolution was the aim of present work.The images of (100),(200),(010),(020),(110) and (110) planes were obtained.2.Several types of the ribbons stacking faults were obserwed in Sb2S3 crystals with (001) parallel to the substrate plane (Fig.1).The stac-kingfault planes and their displacement vectors R are the following: a) (010),(110),R=1/2 [010];b) (100),R=1/2 [210],R=1/4[210].3.There were obtained the images of partial dislocations with b=1/2 [010] and small-andle boundaries,consisted of the dissociated partial dislocation pairs,in Sb2s3 crystals with (100) and (010) planes parallel to the substrate.Small-angle boundaries appeared on initial stage of the spherolite growth,when splitting of spherolite single-crystal nucleus was taking place (Fig.2).
Point defect generation during the oxidation of silicon
Authors: Lambert J.A. , Dobson P.S. 
Published: June 2020

The interstitial defects created during ion-implantation in silicon condense out during annealing to form extrinsically faulted Frank loops and perfect dislocation loops. The annealing behaviour of these defects has been investigated by annealing electron microscope thin foils. It was found that the loops shrink and eventually disappear after annealing in the temperature range 900-1020° C in vacuum. Figure 1a shows faulted and perfect loops after implanting with 10 15 boron ions cm-2 at 40kV and bulk annealing for 50 minutes in nitrogen at 950° C. The thin foil was then annealed for 30 minutes at 1000° C in vacuum and figure 1b shows that the loops have shrunk during this treatment.The loop shrinkage is caused by the diffusion of interstitial point defects from the loop to the surface and the driving force for this process is provided by the self energy of the loops. The rate of shrinkage is given bywhere A is a geometrical factor, Ds is the coefficient of self diffusion and ΔF is
the change in the free energy of the loop per emitted interstitial.