bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electron Source For High-Resolution Video Recording Using Directly Heated Lanthanum Hexaboride Emitter
Authors: Wolter Reinhard F. , Sanders Kenneth 
Published: June 2020

An electron source featuring high brightness and long life has been developed for high-resolution video recording. The electron source is of triode type, and incorporates a directly heated and replaceable lanthanum hexaboride (LaB6) emitter.Since the initial work of Lafferty (1) in 1951, LaB6 has been known as a potential long-life emitter material capable of high emission densities. However, a number of drawbacks have prevented widespread application as a cathode material. These include the high reactivity of LaB6 at elevated temperatures with almost all substrate materials, its sensitivity to corrosion by oxygen-containing gases (2), and fabrication problems due to Its brittleness. Successful operation at high emission densities, therefore, has been reported only by Kapitza, et al (3), and by Broers (4). Kapitza soldered an LaB6 cube to a tantalum heater using MoSi2 in vacuo at 2000°C. This system required a heating current of 50 A. Broers brazed an LaB6 rod to a copper heatsink and indirectly heated the tip of the rod by means of a tungsten coil requiring a power input of 60 W.
A Tilting Cold Stage For The AEI EM802
Authors: Swann P.R. , Swann G.R. 
Published: June 2020

A tilting cold stage of unique design and with exceptional facilities has been developed commercially for the AEI EM802. The design consists of a double tilting stage allowing ±25° of specimen tilt about two orthogonal axes, with specimen cooling to any temperature in the range -150°C to room temperature. Since the specimen plane is maintained at the normal focal position of the objective lens and ‘bumping’ is eliminated by the circulation of gaseous rather than liquid nitrogen, the high resolution of the microscope is maintained.The apparatus consists of a translation stage, A, containing all the tilting controls, a simple specimen cartridge, B, and a hollow annulus, C, clamped to the translation stage, through which flows the cooling gas from the liquid nitrogen Dewar, D.
Preparation of Samples for Scanning Electron Microscopy
Authors: Russ J. C. , Kabaya A. 
Published: June 2020

One of the major advantages of the SEM in material studies is the ease of specimen preparation. For many samples it is only required to cut the sample to size and/or mount it in a suitable holder. However, it is necessary for some materials ( and desireable for others ) to consider other preparation variables:Cleaning : When the sample is mechanically strong enough to withstand it, cleaning in a sonic cleaner is the best way to remove surface dirt. Solvents used in this operation, or for a simple flushing of the surface, should be selected to not leave a residue. Dusting with a Freon jet is the minimum cleaning to be considered.Mounting: For small samples silver paint provides a strong, conductive attachment. Particles that would sink into this can be sprinkled onto doublesided Scotch tape. If the particles themselves do not require coating, the tape can be coated first and retain some adhesion.
Quality of the Secondary Electron Image at Low Accelerating Voltage
Authors: Kosuge T. , Hashimoto H. , Sato M. , Kimoto S. 
Published: June 2020

A scanning electron microscope is usually operated at the accelerating voltage of 25 kV or so. The use of a lower accelerating voltage has many advantages to improve the image quality, such as presentation of fine details of the specimen surface, the prevention of the charge-up and that of the damage to the specimen by electron beam bombardment. In this paper, the quality of the secondary electron image is discussed under various accelerating voltages between 1 and 25 kV.As far it is considered that the limit of the resolution of a secondary electron image is only depend on the diameter of the incident electron probe, the higher accelerating voltage is prefered. Attainable resolutions in this experiment for various voltages are shown in Figure 1. However, as shown in Figure 2 most of the secondary electron images in which a critical resolution is not necessary reveal fine image detail with better contrast at lower voltages.
A Means to Overcome the Contrast Difficulties Inherent to Scanning Electron Microscopy
Authors: Saffir Arthur J. , Woolley Tyler A. , Yew Nelson 
Published: June 2020

The secondary electron image of the scanning electron microscope is similar to a light image of a three dimensional specimen. These two forms of "illumination", light and secondary electrons, have in common a contrast characteristic that makes photography or SEM micrography difficult. .. a tendency toward extreme highlights. The photographer encounters this phenomenon if his subject has a shiny surface, e.g., an automobile bumper. He overcomes this problem with dulling spray to suppress the undesirable highlights (reflections).This problem is also common in SEM studies, especially with biological specimens of poor conductivity. It is undesirable or impossible to subject thermolabile or living specimens to the deposition of conductive coatings.
Irradiation Cascade Threshold Energy in Gold
Authors: Weber D.E. , Hines R.L. 
Published: June 2020

Xenon ions, Xe131, were used to bombard 200A thick, (100) single crystal gold film in a non-channeling direction at room temperature. The incident ion energy was In the 2-40 kev energy range. The ion beam had a uniform current profile which was monitored in two directions before and after the bombardment. The Ion dose levels were of order 1×1010/cm2.The resultant damage was viewed at room temperature in an Hitachi HU 11A electron microscope operated at lOOkev using 200 weak beam techniques. The micrographs of FIG. 1(a) and 1(b) are of the same area at different deviations. FIG. 1(a) represents the image of the damage at low deviation. The high deviation weak beam image is shown in FIG.
The Ordered Phase Formation in Ti-Al-Ga Alloys
Authors: Fujishiro Shiro , Gegel Harold L. 
Published: June 2020

Ordered-alpha titanium alloys having a DO19 type structure have good potential for high temperature (600°C) applications, due to the thermal stability of the ordered phase and the inherent resistance to recrystallization of these alloys. Five different Ti-Al-Ga alloys consisting of equal atomic percents of aluminum and gallium solute additions up to the stoichiometric composition, Ti3(Al, Ga), were used to study the growth kinetics of the ordered phase and the nature of its interface.The alloys were homogenized in the beta region in a vacuum of about 5×10-7 torr, furnace cooled; reheated in air to 50°C below the alpha transus for hot working. The alloys were subsequently acid cleaned, annealed in vacuo, and cold rolled to about. 050 inch prior to additional homogenization
Transmission Electron Microscopy of Green Sheet Ceramic Specimens Prepared by Ultramicrotomy
Authors: Anderson Ronald M. , Schneider Fred W. 
Published: June 2020

It is often desirable to make high-magnification observations of the internal structure of green sheet ceramic. Scanning electron microscopy and replication microscopy have been unsatisfactory in studying the structure of green sheet ceramic. The feasibility of another technique, that of combining ultramicrotomy with transmission electron microscopy (TEM), seemed, therefore, worth investigating. Mullite and alumina green sheets were studied.Narrow (1 × 10mm) strips of green sheet ceramic were cut and mounted in “Beem” microtome capsules. A mixture of Cargille NYSEM epoxy embedding materials was prepared and poured into the capsules, care being taken to keep the specimen centered, especially at the tapered end of the capsule.
Thermally Activated Nucleation and Faceting in Immiscible Cu-Cr thin Films
Authors: Staudhammer K. P. , Murr L. E. 
Published: June 2020

The use of the electron microscope as an experimental chamber in which nucleation and growth observations can take place simultaneously has allowed in-situ studies to be performed on Cu-Cr thin films. Detailed investigations of the time-temperature sequence of events occurring during phase separation of two immiscible materials have been recorded on motion picture film. Each stage in the process of thermally induced phase separation of these thin films has been examined and characterized.Co-evaporation and deposition of Cu-Cr at ambient temperatures on freshly cleaved (100) NaCI substrates results in a polycrystalline two-component structure such as shown in Fig. I(a) where the average particle size was less than 100A. Microprobe data showed the composition of the co-evaporated film to be 59.4 Cu - 40.6 Cr. The advantage of working with unsupported nucle-ation of films of immiscible materials as compared to other techniques of substrate supported nucleation studies lies in the inherent nature of immiscible materials. Because surface diffusion is a controlling mechanism, nucleation, faceting and subsequent growth are more rapid. Exsolved parti-cles once nucleated are three dimensional with minimal constraints, and are on the surface of the thin film as compared to platelet geometries obtained from nucleation and growth on most substrate-type investigations.
Studies on Water in the Hydration Chamber of a Modified Electron Microscope
Authors: Moretz R. C. , Hausner G. G. , Parsons D. F. 
Published: June 2020

Use of the electron microscope to examine wet objects is possible due to the small mass thickness of the equilibrium pressure of water vapor at room temperature. Previous attempts to examine hydrated biological objects and water itself used a chamber consisting of two small apertures sealed by two thin films. Extensive work in our laboratory showed that such films have an 80% failure rate when wet. Using the principle of differential pumping of the microscope column, we can use open apertures in place of thin film windows.Fig. 1 shows the modified Siemens la specimen chamber with the connections to the water supply and the auxiliary pumping station. A mechanical pump is connected to the vapor supply via a 100μ aperture to maintain steady-state conditions.
Pressurized Specimen Chamber for Electron Microscope
Authors: Fukami A. , Etho T. , Ishihara N. , Katoh M. , Fujiwara K. 
Published: June 2020

Electron microscopic observation is confined to dry specimens because the specimen must be kept in vacuum. To extricate themselves from this restriction, several researchers have developed a pressurized specimen chamber which, however, is not satisfactory in reliability; for example,
(1) The Lenard window film is not stable,(2) The atmospheric layer is not so thin as the spacer because of the bend of the Lenard window film,(3) Operation is not easy.Under these circumstances, we have developed a new pressurized specimen chamber, considering the following points;
(1) Strength of the Leanard window films against pressure and electron bombardment,(2) Applicable condition for wide field of research, Ease of opration.(3) Ease of opration.
Combined High Resolution Electron Microscopy and X-Ray Microanalysis
Authors: Cooke C. J. , Openshaw I. K. 
Published: June 2020

The Analytical Microscope EMMA-4 combines the function of high resolution electron microscopy with the facility of x-ray microanalysis. The microscope is a commercially available version of similar instruments which have been previously described. The design of the main console is based on the AEI EM802 with the rear panel suitably modified to house extra controls. An additional console houses the spectrometer controls and affords easy access to the pulse counting electronics. A chart recorder is mounted separately on a mobile trolley.The Figure shows the electron optical column of the instrument and the position of the two x-ray spectrometers. The objective lens accommodates a side entry specimen stage which permits six specimens or standards to be loaded into the instrument at any one time. By using the normal projector system of the EM802 a direct magnification of about 140,000 times is possible and the resolution is better than 10Å.
Epitaxy of Molybdenum on Sapphire
Authors: O'Neal J. E. , Rath B. B. 
Published: June 2020

Thin films of molybdenum were deposited by the electron beam evaporation method on single crystal sapphire substrates to establish the effects of substrate orientation, deposition temperature, and evaporation rate on the structure, orientation and morphology of the deposited films. The films were characterized by replication and high resolution reflection electron diffraction methods.The epitaxy of molybdenum on sapphire substrates of orientations (0001), (1012), and (1012) were studied over a substrate temperature range of 25 through 1000°C with deposition rates of 500 and 1000 Å/min. Strain-free substrate surfaces were prepared by removing the disturbed surface layer by means of thermal etching in-situ at 1450°C for 2 hours in a pressure of 10−9 Torr.
Studies of Laser-Metal Interactions using a Coupled Laser-SEM System
Authors: Magee T. J. , Krehl P. 
Published: June 2020

With the advent of new high-power laser systems and the increasing variety of scientific, commercial, and military applications, a more detailed understanding of laser-metal interactions is required. Of particular importance are the induced surface damage, plasma-plume diagnostics, shockwave initiation, and internal structural damage during high-power pulsed laser loading.In the present program, a Cambridge scanning electron microscope (SEM) has been modified to accept a focused laser beam into the sample cavity. An external high voltage relay, triggered from the frame generator at the start of the laser pulse, provides a finite time lag of 50 to 100 milliseconds before the onset of framing.
Diffusion of Zn into GaAs Inside the Transmission Electron Microscope
Authors: Rhines W. C. , Stevenson D. A. , Barrett C. R. , Anderson L. J. 
Published: June 2020

A technique was developed to directly observe the dislocation generation that occurs during Zn diffusion into GaAs. The method is applicable to a wide variety of materials where phase transformations or lattice strain resulting from impurity diffusion is of interest, and where the need exists to observe the material while the transformation or strain is occurring.Zinc diffusion in GaAs and other III-V compounds is of interest because of its application to the fabrication of light emitting diodes and injection lasers. Numerous reports exist in. the literature concerning the high density of dislocations (>108cm−2) and the presence of precipitates found in GaAs after Zn diffusion. Dislocations and/or precipitates seriously impair the performance of light-emitting devices.
Control of Metal Alloy Oxidation with Electric Fields
Authors: Dils R. R. , Follansbee P. S. 
Published: June 2020

Electric fields have been applied across oxides growing on a high temperature alloy and control of the oxidation of the material has been demonstrated. At present, three-fold increases in the oxidation rate have been measured in accelerating fields and the oxidation process has been completely stopped in a retarding field.The experiments have been conducted with an iron-base alloy, Pe 25Cr 5A1 0.1Y, although, in principle, any alloy capable of forming an adherent aluminum oxide layer during oxidation can be used. A specimen is polished and oxidized to produce a thin, uniform insulating layer on one surface. Three platinum electrodes are sputtered on the oxide surface and the specimen is reoxidized.
Phase Transformations in Co5Sm
Authors: Rao P. , Smeggil J.G. , Koch E.F. 
Published: June 2020

Much higher magnetic coercivities than were previously available have been attained with the compound Co5Sm. However, coercivity is very sensitive to heat treatment; in particular, annealing near 750°C substantially reduces coercivity. This has been attributed to a possible eutectoidal decomposition of Co5Sm into CO17Sm12 and CO7Sm12 on the basis of optical metallography. This possibility makes it necessary to obtain basic electron microstructural information from CO5Sm heat treated in this temperature range.High quality Co5Sm crystals were annealed in sealed Mo bombs at 750°C for 10 days. Electron transparent specimens were prepared by ion thinning in a commercialion milling apparatus.
Minority-Carrier Diffusion Lengths in GaAs:Ge by Scanning Electron Microscopy
Authors: Levin Edwin R. 
Published: June 2020

Scanning electron beam determinations of minority-carrier diffusion lengths in semiconductors have been viewed with some suspicion, because of uncertainty about the influence of surface recombination. We have recently made a series of observations which show that the bulk and surface effects can be easily separated, so that reliable volume diffusion lengths are obtained by the scanning beam method.The specimens were GaAs diodes grown with varying concentrations of Ge in the p-layers. The diodes were cleaved normal to the pn junction and examined in a Cambridge Stereoscan, with the beam normal to the cleaved surface and linescanned in a direction perpendicular to the line of intersection of the junction with the surface.
Study of TE Puke Halloysite by a High Resolution Electron Microscope
Authors: McKee T. R. , Dixon J. B. , Whitehouse U. G. , Harling D. F. 
Published: June 2020

Clay minerals normally exhibit platy morphology with basal spacings parallel to the surface of an aggregate and registering characteristic x-ray diffraction effects. For the same reason the majority of the electron microscopic lattice imaging has been accomplished using embedded and ultrathin sectioned clays, allowing the basal spacing to be correctly oriented with respect to the electron beam. Yada has observed lattice spacings in chrysotile (a tubular mineral) by direct examination.Halloysite is a type of kaolin clay mineral that usually exhibits curved layers as tubes and spheroids which reduces the x-ray diffraction intensities from preferred orientation mounts while exposing the basal spacing for electron diffraction investigation and lattice imaging.
Application of a Simple Cold Stub to the Direct Observation of Frozen Hydrated Sand
Authors: Wehrung John M. , Harniman Richard J. 
Published: June 2020

Water tables in aquifer regions of the southwest United States are dropping off at a rate which is greater than can be replaced by natural means. It is estimated that by 1985 wells will run dry in this region unless adequate artificial recharging can be accomplished. Recharging with surface water is limited by the plugging of permeable rock formations underground by clay particles and organic debris.A controlled study was initiated in which sand grains were used as the rock formation and water with known clay concentrations as the recharge media. The plugging mechanism was investigated by direct observation in the SEM of frozen hydrated sand samples from selected depths.
Techniques For Ultra-Thin Apertures
Authors: Eisner Paul R. 
Published: June 2020

Ultra-thin apertures function longer with negligible astigmatic effect and require less maintenance than conventional thick apertures. They resist contamination because they are heated by the electron beam, and the ultrathin edge offers minimal area for formation of a charged layer of contamination. Ledbetter and Dell described making ultra-thin apertures by evaporating metal over spheres of dextran on a collodion membrane. An alternative procedure for making ultra-thin apertures is given in detail here along with a method for extending aperture life.Ultra-thin apertures can be piade for less than the cost of conventional thick apertures. Copper specimen grids 2 or 3mm diameter with a circular opening 600μm diameter are coated with 50nm thick Formvar film according to the technique given by Bradley.
A Method For Maintaining Specimen Hydration by Sandwiching Between thin Films
Authors: Taylor Kenneth A. , Glaeser Robert M. 
Published: June 2020

A major goal of electron microscopy is the visualization of biological specimens in the hydrated state. One method to maintain this specimen hydration is by sandwiching the specimen between thin hydrophilic support films and observing it frozen on a liquid nitrogen cooled stage. Sufficiently thin films of ice are produced so that the specimen can be observed embedded in the ice.The formation of thin films of ice can be demonstrated by placing a drop of distilled water between two halves of a folding grid which has previously been coated with a thin hydrophilic support film.
Immunoperoxidase Labeling of a Nucleolar Antigen in Human Melanoma Cells by Sera of Melanoma Patients
Authors: Miller M. F. , Bowen J. M. , Angermann J. , McBride C. M. , Dmochowski L. 
Published: June 2020

We have previously demonstrated by the indirect immunofluorescence test that sera of some patients with malignant melanoma contain antibodies to antigens associated with nucleoli of their own and homologous melanoma cells. These studies have shown a correlation between the presence of nucleolar antigen in tumor cells of a melanoma patient, progressive tumor growth, and poor prognosis. The present study was undertaken to determine if nucleoli of melanoma cells possess any unusual morphological features and to demonstrate the nucleolar antigen at the light and electron microscope level by the immunoperoxidase reaction.Melanoma cells from selected patients were examined by electron microscopy after growth in tissue culture.
An in Vitro Study of Necrosis in the Crayfish Giant Axon
Authors: Sides Paul J. 
Published: June 2020

Several electron microscopic studies have shown that in some types of cells allowed to undergo necrosis on exposure to various injurious agents, there are discrete and predictable alterations in ultrastructure. In crayfish nerve cords exposed to in vitro anoxic conditions, necrosis also proceeds in an orderly manner. These changes are characterized by alterations in Schwann cell morphology occurring shortly before discernable changes in the axon proper.Ventral nerve cords of the crayfish (Procambarus clarkii) were dissected, divided into control and experimental portions after tieing the ends with thread, and mounted in covered plastic Petri dishes which contained 50 ml.
Pulmonary Acariasis: A Scanning Electron Microscope Study of Lung Mites in the Rhesus Monkey
Authors: Brummer M. E. , Darby R. E. , Wong M. M. 
Published: June 2020

Infestation by the mite Pneumonyssus simicola causes pulmonary acariasis in several simian primate species, particularly the rhesus monkey, Macaca mulatta. These lung mites, common in Old World monkeys captured in the wild, are infrequently encountered in monkeys born and raised in captivity. The mite infestation is usually asymptomatic and clinically not detectable. Since the lesions caused by the mites may complicate experiments in pulmonary research and make interpretations of results difficult, studies were made to characterize the lung mites and lesions to minimize this problem.Lungs from four Macaca mulatta were fixed by perfusion via the airways at 30 cm of water pressure with cacodylate-buffered formaldehyde-glutaraldehyde.
Inelastic Scattering and Beam Damage of Biological Molecules
Authors: Isaacson M. 
Published: June 2020

There are two kinds of interactions which an incident electron can experience in traversing a thin specimen. It can be elastically scattered from the atomic nuclei without losing energy. Or it can be inelastically scattered from the atomic electrons and impart energy to the specimen. Elastic interactions are useful for high resolution imaging and produce negligible damage. Inelastic interactions, however, can result in molecular or chemical damage. This is important in biological electron microscopy, since experiments have shown that for 30 KeV electrons in carbon one gets 1.6 inelastic events for every elastic event. Moreover, this ratio increases slightly with voltage.The energy loss spectrum of electrons which have traversed thin specimens is directly related to the probability of exciting a particular electronic level.