bluuebunny/crossref_metadata_2025 huggingface dataset:
Applications of X-Ray Analysis to Environmental and Biomedical Studies
Authors: Gilfrich John V.
Published: March 2019

Recent developments in x-ray spectroscopy have shown that this technique is a very powerful tool for the analysis of small quantities of material. A distinction must be made here between microanalysis -the analysis for elemental composition of a small total amount of material - and trace analysis - the analysis of bulk material for the presence of certain elements at very low concentrations. By the use of chemical separation, a problem in trace analysis can be converted into a microanalytical situation. A major improvement in trace analysis has been achieved by the use of ion-exchange resin loaded onto filter paper to collect the element(s) of interest from a solution of the original sample. The analysis of these concentrates or of particulate matter filtered out of polluted air or water can be optimized because the total mass of the sample is small and the background due to scattered prirmary radiation can be minimized.

Much interest has become manifest recently in the use of solid-state detectors for energy dispersion x-ray analysis of samples of this type. The value of energy dispersion can be demonstrated by improved detection limits for samples containing only a few widely separated elements. However, resolution of state-of-the-art solid-state detectors is not adequate to separate the Kβ of one element from the Kα of the next higher atomic number among the transition metals. Thus the presence of a large number of immediate neighbor elements at widely different concentrations as in pollution samples suggests the need for crystal spectrometers.
Differential Photoionization Cross Section of Neon Subshells for the X-Ray Analysis by Photoelectron Spectrometry
Authors: Wuilleumier François
Published: March 2019

The new x-ray analysis method using photoeleetron spectrometry demands knowledge of differential photoionization cross sections of the subshells of the converter atoms used as intermediary between the x-ray spectrum and the photoelectron spectrum. These differential cross sections were determined for the most appropriate converter, the neon atom, in the energy range from 50 to 3000 eV. The total photoionization cross section was partitioned into contributions that arise from single ionization in the various subshells and from multiple processes. We present in tabular and graphical form: a) 1s, 2s and 2p total subshell cross sections; b) 1s, 2s and 2p differential cross sections at 54.73°; and c) ls, 2s and 2p differential cross sections at 90°. Accuracy is considered to be better than 3%, 7% and 5% at all energies for 1s, 2s and 2p cross sections, respectively.
An Energy Dispersive System for the Analysis of Trace Elements in Human Blood Serum
Authors: Ong P. S. , Lund P. K. , Litton C. E. , Mitchell B. A.
Published: March 2019

A computerized systetn, consisting of a fluorescence x-ray source (Philips), an Si (Li) detector (Ortec), and a mini Computer (Xerox) is currentiy in operation at The University of Texas M. D. Anderson Hospital and Tumor Institute, Experimentel Pathology Section, for the analysis of trace elements in biological specimens. The elements of interest are Fe, Cu, and Zn for possible significance in the detection and study of cancer. The detection system is being used for comparatively routine analysis of these elements, which are present in blood serum in the ppM range. With appropriate sample preparation techniques, using 1 ml of serum, the limit of detectability for these elements is estimated to be 100 ppB (1 in 107). Further refinement is possible, and research in this direction continues.
X-Ray Energy Analysis of Particulate Matter on Filter Paper
Authors: Wood Warren G. , Mathiesen James M. , Mgebroff John S.
Published: March 2019

The rapid, quantitative and qualitative analysis of particulates on air filter samples is becoming increasingly important as more air pollution sampling stations are set up throughout the countiy. Although atomic absorption provides a sensitive technique for the analysis of many elements, the disadvantages of complex sample preparation, sample destruction and the necessity to analyze one element at a time make this technique unsuitable for a large volume of samples. X-ray energy spectroscopy when combined with automated sample handling and the latest dedicated data reduction systems provides a technique which enables the analyst to process large numbers of samples and obtain precise quantitative and qualitative data rapidly. This paper will describe the preparation and analysis of typical air filter type samples, and the steps taken to identify the elements in the samples and obtain computerized reduction of the data in μg/cm2, ppm or percent.
X-Ray Spectrometric Determination of Atmospheric Aerosols
Authors: Chessin Henry , McLaren E.H.
Published: March 2019

X-ray spectrometric analysis is examined as an analytical tool for elemental determinations of atmospheric aerosols. Contamination levels of the several filters used for collection purposes are examined and the results reported. A calibration technique is described for analysis of several elements in the microgram range based on collection of saturated vapors of aqueous salt solutions. The calibration curves together with an analysis of sensitivity and lower limits of detection are shown. The technique is employed to monitor continuously aerosol content in the atmosphere during passage of a cold front.
Three Dimensional X-Ray Image Synthesis
Authors: Grant David G.
Published: March 2019

Tomographic systems are able to produce cross sectional planar images of three dimensional volumes because of the relative motion of the source, film and the volume under examination. Analysis shows that the image produced is a result of a three dimensional linear filtering process where the filter characteristics are determined by the scan geometry (3). If, instead of integrating continuously on a single film, a set of N radiographs are recorded, each corresponding to a point along the scan trajectory, then a simple filter can be defined to reconstruct the entire three dimensional structure from this data. In this case, the transfer function exhibits repetitive peaks whose spacing is determined by N and whose width is determined by the total scan length. The number of views required to produce the same “blurring” as the continuous case can then be determined by the Nyquist criteria(3).

An optical projection system based on circular geometry for producing three dimensional medical images has been fabricated and tested. The technique can be generalized to any geometry and to all x-ray applications where plane-by-plane examination of a structure would prove beneficial.
Computer Controlled X-Ray Diffraction Measurement of Residual Stress
Authors: Kelly Carol J. , Eichen E.
Published: March 2019

The system to be described includes hardware and software for the on-line computer control of the X-ray diffraction measurement of residual stress. This determination involves accurately measuring the angles at which a back-reflection line is diffracted, first by diffracting planes parallel to the sample surface, and then by planes at an angle (ψ) to the sample surface. The residual stress is calculated from the difference in the two measured diffraetion angles. The procedure executed by the computer consists of locating the peaks, selecting three angles for collection of X-ray counts, correcting the measured counts, fitting the equi-angular intensity measurements to a three-point parabola, calculating the peak angles, calculating the residual stress from the measured angles and typing a report. This automation has eliminated the tedium of the manual X-ray data accumulation and of the residual stress calculation. The online control has also permitted improvements in the technique not practicable with the manually performed measurement of residual stress.
The X-Ray Diffraction Image of a Stacking Fault
Authors: Kato Norio , Usami Katsuhisa , Katagawa Takeshi
Published: March 2019

The spherical wave theory of X-ray Pendellosung fringes in perfect crystals (N. Kato, Acta Cryst, 14: 526, 627, 1961) is extended to the case of crystals including a single stacking fault in an arbitrary way, Kelvin's stationary phase method is used extensively. The stationary phase condition gives us the trajectories of X-ray beams in the crystal. The phase and the amplitude along each trajectory are obtained by straightforward calculation. Based on this crystal wave field, the section patterns in X-ray diffraction topographs are obtained both for the direct and the Braggreflected waves. Characteristic fringe-patterns are expected. Through the image of a fault plane in a single section pattern, the geometrical configuration inside the crystal and the magnitude of the fault vector can be determined. Traverse patterns are also discussed. The fault image based on the plane wave theory (Whelan and Hirsch, Phil. Mag. 2: 1121, 1303, 1957) is also reformulated in the most general Laue case without the use of ad hoc assumptions on the shape of the dispersion surface.
Lattice Constant and Crystallite Size of Condensed Gold Vapor
Authors: Karioris Frank G. , Woyci Jerome J. , Buckrey Richard R.
Published: March 2019

Gold wires were vaporized by the exploding-wire phenomenon using a 20 μF capacitor bank charged to voltages up to 14 kV. The resulting condensate, an aerosol or metallic smoke, was collected on membrane filters and subjected to X-ray analysis to determine lattice constant, crystallite size, and behavior with isothermal annealing. Wire explosions were conducted in au ambient atmosphere of ait or nitrogen at barometric pressure. It is estimated that the quench rate for this material is of the order of 108 deg/sec from the melting point although no substrate is involved and it is expected that any effects of epitaxial origin on the structure would be minimized.

Before annealing, diffractograms showed broad peaks apparently shifted to the high-angle side. Line breadth may be attributed primarily to particle size broadening, since ft correlates well with size determined by electron microscopy, (β cos θ) is linear with θ, and [(β cos θ)/λ] is approximately constant for three radiations used. Crystallite size is of the order of 400 Å and is observed to decrease roughly with increasing voltage used for vaporization. The observed lattice decrement, approximately 0.2%, generally increases with voltage used for vaporization, and apparently correlates rather well with the inverse of sise as has been reported in some work on thin gold films. However, studies of colloidal gold particles do not show significant lattice shifts, although the particle size is less than 100 Å so that the decrements observed may be due to factors other than size alone. For this black, particulate material, some lattice decrement apparently persists even after protracted isothermal annealing below the melting point. Crystallite size increases with annealing but remains below about 1000 Å. Results suggest that the lattice decrements observed in condensed gold vapor are due to surface tension effects and the presence of vacancy aggregates.
The Application of the Electron Microprobe in the Analysis of Nuclear Fuel Meltdown Experiments*
Authors: Stachura S. J. , Cooper L.
Published: March 2019

Transient (nuclear) heating experiments were conducted with uranium carbide fuel rods to study the failure characteristics of typical rod designs. Extremely unusual changes in microstructure were observed and the electron microprobe was employed to establish the disposition of materials resulting from the meltdown experiments. The probe results indicated substantial fuel-clad interactions and permitted the resolution of several uncertainties regarding the course of fuel rod failure and material redistribution. The electron microprobe represents a unique capability in the post-test analysis of such meltdown tests.
Characteristics of Flow Proportional Counters for X-Rays
Authors: Spielberg N.
Published: March 2019

Gas flow proportional counters for the detection of soft X-rays were introduced about ten years ago. These detectors offered the advantages of high sensitivity, good energy discrimination qualities and the ability to handle high counting rates. Since that time they have been used for ultra-soft and harder X-rays as well, both as detectors in standard spectrographic instruments and as energy discriminating instruments themselves in various so-called nondispersive applications. Depending upon the particular instrumental application, however, their use has led to considerable complication of the associated electronic circuitry in order to realize their advantages. For the most effective use of these counters (and of sealed proportional counters as well) it is necessary to have a clear understanding of the effect of various design parameters and operating conditions on their performance. The dependence of the shape of the pulse height distribution on the operating voltage, pressure and counting rate is described as a function of the energy of the radiation detected and the nature of the gas. Stability requirements on. counter tube high voltage supplies and operating pressure are discussed. Shifts of pulse height distributions toward smaller pulse sizes with increasing counting rate are described and the dependence of these shifts on the various parameters and on wavelength are discussed. Techniques for eliminating the shifts and the implications of these techniques for the associated electronics are described.
X-Ray Fluorescence Analysis of a Manganese Ore
Authors: Egan W. D. , Achey F. A.
Published: March 2019

To replace time-consuming chemical analysis, a procedure was developed for applying X-ray fluorescence to the analysis of a manganese ore. This X-ray fluorescence method is rapid; the total time for both sample preparation and analysis is ½ hr. The method is also simple enough for routine laboratory use. The components determined, the concentration ranges, and the agreement between chemical and X-ray analysis in terms of standard deviation are:

The agreements between chemical and X-ray analysis noted for manganese and iron are obtained by correcting for CaO concentration when determining the manganese and for manganese and SiO2 concentrations when determining the iron. The corrections employ empirical equations developed by a multiple regression technique.

Sample preparation is reduced to a minimum because it consists of only two steps, pulverization of the manganese ore followed by briquet ring. Four minutes of grinding with Boraxo as the grinding aid gives sufficient uniformity to minimize the effect of particle size variation. The ground mix of manganese ore and Boraxo is pressed into 1.25-in. briquettes for analysis.
Standard Reference Materials and Meaningful X-Ray Measurements
Authors: Thomas Yolken H.
Published: March 2019

A review of the procedures and efforts at the National Bureau of Standards (NBS) to provide for meaningful measurements through the use of Standard Reference Materials (SRM's) is presented.

The examples of NBS Standardization efforts for x-ray analysis range from basic metrology to applied environmental measurements. These examples include a determination of x-ray wavelength by a method which in part utilizes simultaneous x-ray and optical interferometry measurements of the atomic planes of near perfect silicon. In addition, Standard Reference Materials (SRM's) are being developed and applied to trace element analysis using x-ray fluorescence techniques. These efforts include development of SRM's for trace element analysis of air particulates. In another area, work is proceeding on the development of a silicon powder Standard Reference Material intended for x-ray diffractometer calibration. An effort to develop a suitable x-ray diffraction technique to determine the amount of quartz in mine dust is also underway. NBS efforts to provide SRM's for the calibration of electron microprobes and the validating of correction factor calculations are also described.
Standard Reference Materials - Their Production and Use
Authors: Gillieson A. H.
Published: March 2019

The purpose and the value of standard reference materials (S.R.M.) are defined, and their increasing world importance is emphasized. The desirable features of an S.R.M. are outlined and the procedures necessary to meet, as far as possible, the necessary requirements in S.R.M. production are discussed. The method and organization of certification for homogeneity and composition are detailed, as well as the statistical proceduces to evaluate the certification analysis. The present Status and future plans for the production of S.R.M.'s by the Canadian Standard Reference Materials Project, Mines, Branch, Department of Energy, Mines and Resources, are outlined.
Quantification of Sub-Microgram Elemental Concentrations Using Micro-Dot Samples
Authors: Mathiesen James M.
Published: March 2019

The following study describes the experimental results obtained by energy dispersive x-ray analysis on a series of representative samples, concentrated by precipitation, to spots 1.5 mm in diameter on Millipore (R) membranes.

Using modified detector collimation, the contributions of air scatter and membrane (Substrate) scatter to the background under a peak, can be minimized to achieve limits of detection approaching a nanogram of the element present in the precipitate.

The equipment used here is composed of an 80 mm2 Si(Li) detector connected to a computer based data handling unit. Excitation was achieved with a Rhodium target x-ray tube having a maximum output of 50 kV at 5.0 ma. Even with the high detection efficiency of the Si(Li) detector and the capability of minimizing the source to sample and sample to detector pauh lengths, it was found with these samples that at least 3.0 ma of tube current is needed in the excitation source.

A mechanism has been developed for this work that allows reproducible sample positioning for standards and unknowns. This mechanism is used to produce element profiles on larger precipitated standards to measure radial uniformity.
A Rapid Direct X-Ray Fluorescence Method for Simultaneously Determining Brass Composition and Plating Weight for Brass-Plated-Steel Tire Cord Wires
Authors: Gianelos James
Published: March 2019

A rapid direct x-ray fluorescence (XRF) method has been developed for simultaneously determining brass composition and plating weight for brass -plated-steel tire cord wires. On a manual XRF instrument, a complete analysis can be done in ten minutes including calculations. A complete analysis can be done in only two or three minutes on a multi-channel Quantometer-type instrument. The method can easily be adapted to “on line” use.

Analysis is done directly on the “as received wires. Sample preparation is simple and non-critical with no surface pre-treatment of any kind required. Sample weighing and dissolution of the brass plating are entirely eliminated. Wire samples may be either stranded or unstranded. Rather large variations in sample size can be tolerated because of the ratio-type calculation system used. Analytical precision is high.

Calibration curves were established by wet chemical, atomic absorption, and solution-XRF methods. No serious calibration problems were encountered because the plating is an alloy, or because count data were taken from round, non-flat samples. Low impurity levels of iron in the brass plating are shown to have an insignificant effect on the plating weight calibration curve.
X-Ray Emission from Laser-Produced Plasmas
Authors: Dozier C. M. , Burkhalter P. G. , Klein B. M. , Nagel D. J. , Whitlock R. R.
Published: March 2019

Intense x-rays are emitted by plasmas formed when sub-nanosecond laser pulses are focused onto materials, Plasmas produced by pulses containing up to 100 J can re-emit over ten percent of the energy as x-rays above about 1.0 keV. These plasmas may be useful flash x-ray sources.
Some Biomedical Applications of Charged-Particle-Induced X-Ray Fluorescence Analysis
Authors: Campbell J. L. , Herman A. W. , McNelles L. A. , Orr B. H. , Willoughby R. A.
Published: March 2019

X-ray fluorescence induced by charged particles has been employed in trace element analysis of both animal and human blood, tissue and bone samples. Preparation techniques included microtome slicing and wet digestion in nitric acid, internal chemical standards being used in the latter case.

Most of the specimens arose from a study of interactions between the toxic elements lead and zinc in growing foals; this was motivated by reports of sickness and death in foals raised near lead-zinc smelters. The cause of toxicity in animals from environmental pollution is often attributed to Single factors, whereas in reality interactions among many factors, including a variety of toxic and nutrient trace elements, should be considered.

A variety of spectra are presented and elemental concentrations derived. Agreement between the X-ray data and atomic absorption spectrophotometry is encouraging. The results demonstrate the potential of particle-excited X-ray fluorescenee as a broad-range analytical technique for the study of trace element interactions.
Auger Electron Emission Micrography and Microanalysis of Solid Surfaces
Authors: Hayakawa K. , Okano H. , Kawase S. , Yamamoto S.
Published: March 2019

An electron probe Auger emission microanalyzer has been constructed. The instrument is composed of an electromagnetic focussing primary probe column and a cylindrical mirror electron energy analyzer. By using this instrument, Auger electron spectroscopy studies have been carried out in the modes of both emission microanalysis and emission micrograph. The feasibility o£ this method is investigated through its application to the study of iron surface.
Close-Packed Ordered Alloys
Authors: Beck Paul A.
Published: March 2019

Systematic procedures are used for generating the geometrically possible close-packed ordered layers for any desired binary “ideal composition” and the various geometrically possible stacking sequences with a given number of layers of known structure. The known ordered close-packed cyrstal structure types in AB3 and AB4 alloys are characterized by the structure of the layer and by the stacking sequence. Their occurrence is reviewed in relation to pertinent variables, such as electron concentration and atomic size.
A Study of Guinier-Preston Zone Growth Kinetics Through the Use of X-Ray Small-Angle Scattering*
Authors: Harkness Samuel D. , Gould Robert W.
Published: March 2019

The relation of the X-ray small-angle scattering parameters to the results of transmission electron microscopy for spherical Guinier-Preston zones was investigated. Experimentally, the Guinier radius is found to equal (/1/2) and the Porod radius to equal /. These results were theoretically predicted by Baur and Gerold, A log normal distribution was found to be in close agreement with the experimental data. The use of this distribution allowed the size-distribution curve of spherical Guinier-Preston zones to be constructed from the X-ray parameters and from a knowledge of the metastable miscibility gap. This approach is used to follow the evolution of size distribution in both Al-Ag and Al-Zn alloys. The application of this approach to nncleation and growth as well as redistribution processes is discussed. Growth paths are established from the size distribution evolution curves through an Nv> construction. A brief discussion of the technique is included.
Antiphase Domains in Long-Period Superlattices
Authors: Chaudhari P. , Gangulee A.
Published: March 2019

The antiphase boundary in a superlattice has been defined as the boundary between two neighboring zones which are out ofsphase with each other. This difference in phase is usually represented by a translation vector. In long-period superlattices, however, antiphase boundaries of the above mentioned type occur with regular spacings, thereby introducing another element of order which shows up as satellite peaks in the diffraction pattern. A second kind of antiphase boundaries may be defined in a one-dimensional long-period superlattice as the boundary between two neighboring zones which have different directions of repetition of the antiphase boundaries of the first kind. A theory of X-ray diffraction to obtain the size of the domains of the second kind in a one-dimensional long-period superlattice has been developed. An application of this theory to the ordered alloy Ag3Mg, known to have a one-dimensional long-period superlattice, is described and the results of the X-ray measurements are compared with those obtained by transmission electron microscopy.
A High-Precision Kossel Camera for Research and Routine Analytical Use
Authors: Reichard T. E.
Published: March 2019

A transmission Kossel camera unit has been built for the Cambridge Mark II electron probe. It replaces the standard specimen stage assembly, and is useful also for regular electron probe microanalysis and projection microradiography.

Its design extends the attainable precision of lattice parameter measurements to near-ultimate practical limits, while providing special features for research studies, and speed, flexibility, and convenience of operation for routine analytical use on a wide variety of specimens, particularly semiconductor materials.

The most significant feature is a novel X-ray projection box structure which casts index-mark images on each pattern. From these images, the exact source distance and pattern-center positions are determined for each exposure. Precise crystal-piane spacings can be measured, therefore, from conic intersections anywhere on the exposed area of the plate. Since the conics need not be in any particular favorable location, it is not necessary to achieve an exact orientation of the sample. Precise lattice dimensions in several different crystallographic directions are obtainable from a single pattern exposure if their various sensitive conics appear anywhere on the pattern. The need for a reference measurement of “fixed” conics is eliminated, being replaced by a much more precise measurement of very sharp, high contrast, widely spaced index-mark images.

Camera length is 12.5 cm and exposed pattern area is 9.4 cm square. Glass photo plates are used to eliminate errors due to film shrinkage and warp. A removable cassette holds ten 4″×5″ glass plates, interchangeableiunder vacuum. The X-ray shutter has ten positions for making exposure-time sequences. The specimen stage is thermostatted to ±0.01° C, controllable from room temperature up to 200° C, and;temperature is measured to +0.005° C. Stage movement range is 25mmx50mn, with coordinates shown on external digital dials. Interchangeable inserts provide for a wide range of specimen sizes and shapes. Electrical contacts to the specimen are available.

An externally adjustable plate holds 24 different target foils or target-filter combinations for pseudo-Kossel patterns. An open position provides for true Kossel work and for scatteredelectron image viewing.
X-Ray Diffraction Study of the Effects of Uniaxial Plastic Deformation on Residual Stress Measurements
Authors: Esquivel A. L.
Published: March 2019

Uniaxial Plastic Deformation (UPD) has been known to produce anomalies in residual stress measurements based on x-ray diffraction techniques. This study was undertaken to determine the magnitude of the effects, if any, on residual stress calculations from various materials subjected to UPD. An x-ray diffraction study using the two-exposure method ( ψ = 0° and ψ = U5°) was made on several iron, aluminum, and titanium alloys (AISI 4340, 4330M, 4130; 2024-13, 7075-T611; Ti-6Al-4V) before and after these alloys were deformed plastically by bending on a U-bend test fixture. The x-ray peak shifts, Δ2θ0-ψ, were recorded and the x-ray stress factors, Ki, calculated by three different methods. The results indicate that UPD of the calibration specimens will increase or decrease Ki depending on the alloy. These results are discussed together with observations on the additivity of residual and applied stresses, and the per cent differences in the stress measurements based on stress factors calculated by three different methods.
Role of Residual Stresses as Determined by X-Ray Diffractometry on Magnetic Properties of 4-79 Molybdenum Permalloys
Authors: Bhattacharyya A. , Darling H. E.
Published: March 2019

Residual stresses in several batches of heat-treated 4-79 molybdenum Permalloy finished laminations were measured by X-ray diffraction technique. This involved determination of macrostresses from line shift of (331) reflection by the two-exposure diffractometric technique as well as the determination of microstresses from half breadth of the same line profile. It was observed that the residual stresses In all batches of laminations were small and the variations in residual stresses from one batch of laminations to another were not appreciable, considering the scatter in laminations within each individual batch. Simultaneous magnetic measurements showed considerable variation in magnetic properties from batch to batch; e.g., a five-fold variation in normalized hysteresis loop and a two-fold variation in the magnetic “softness” parameter. On subjecting individual batches of laminations to various thermal and thermomagnetic treatments below 650 C, considerable change in magnetic properties was achieved without significantly changing residual stresses. The variation in magnetic properties in finished laminations was ascribed to the difference in effective crystal anisotropy and uniaxial anisotropy caused by variations in thermal and thermomagnetic annealing treatments. The study showed that the variation was not due to any major variation in stress induced magnetostrietive anisotropy.
X-Ray Studies of Plastically Deformed Silver Alloys - Effects Due to Oxygen, Hydrogen, and Tin Solutes*
Authors: Newton C. J. , Ruff A. W.
Published: March 2019

Solid specimens of silver were charged at different temperatures in atmospheres of oxygen and of hydrogen. X-ray diffraction line profiles were obtained using powders filed from the treated specimens. Fourier analysis of the diffraction lines was conducted following the method of Warren. The effective particle sizes and root-mean-square strains were obtained from the line shape analysis. Stacking fault and twin fault probabilities were determined from peak-position and center-of gravity displacements, respectively. For the purpose of comparison, two vacuum-melted silver samples and two different silver-tin alloys were studied. The stacking fault and twin fault probabilities were observed to be nearly unaffected by charging in either oxygen or hydrogen. These results are consistent with recent direct determinations of the effect of oxygen on the stacking fault energy of silver. In contrast, the rms strains and particle sizes changed significantly after charging in oxygen. A decrease in the root-mean-square strain and a corresponding increase in the particle size was found. These effects were opposite to those obtained by adding substitutional solute to silver. These findings are interpreted to indicate the effect of oxygen clustered with impurities on the dislocations and stacking faults in silver.
Precise Cell Parameters of Semiconductor Crystals and their Applications
Authors: Pierron E. D. , McNeely J. B.
Published: March 2019

A precise method for detenaining unit cell dimensions of semiconductor single crystals has been developed. An accuracy of ± 0.00002 Å and a precision of ± 0.00001 Å is achieved.

The method is used to determine variations in the cell parameter of GaAs as a function of surface defects, homogeneity across and along an ingot, evaluation of epitaxial layers, effects of heat treatments and structure defects induced by oxide diffusion masks on a substrate. The application of the technique to GaAsP alloys permit accurate and rapid study of sample composition and homogeneity.
Direct Printout X-Ray Pole Figures from Digital Computers
Authors: Chao Hung-Chi
Published: March 2019

The texture of sheet metal Is best described, by means of pole figures, which are very expensive and time-consuming to prepare. About 8 to 12 hours of effort by a specially trained, and. highly skilled technician are needed to prepare each pole figure. Accordingly, pole figures are not used as extensively in research studies as they would, be if they could be obtained more easily.

A method has been developed for automatically producing pole figures by printing results directly from a digital computer. This method does not require the use of additional plotting attachments and, is therefore less expensive and time consuming than other methods. With this method, any laboratory with access to a digital computer can produce pole figures automatically.

X-ray diffraction intensities are recorded on punched tape or on punched cards and are fed into the digital computer. A computer program corrects X-ray data obtained, by either transmission or reflection X-ray techniques, maps the stereographic projection, and prints pole figures directly. The time required, to prepare an accurate pole figure is reduced from 8 to 12 hours to 20 minutes or less depending on the type of digital computer used.
A Computer-Controlled X-Ray Diffractometer for Texture Studies of Polycrystalline Materials
Authors: Desper C. Richard
Published: March 2019

The Picker Four-Angle Computer System (FACS-1), a computercontrolled x-ray diffractometer originally designed for single crystal studies, has been adapted for use with polycrystalline samples. The system is controlled by a PDP-8S, a small time-sharing computer with teletype input and output. Programs have been written to take advantage of the high degree of flexibility inherent in online computer control. Four basic operations are possible: (a) simple 2θ step-scanning with variable step width; (b) 2θ stepscanning with randomization of orientation; (c) determination of Legendre expansion coefficients for oriented specimens; and (d) determination of pole figures. In operation (a), data is gathered at a series of 2θ values at a prefixed count and/or time. In (b), the sample is rotated to average out orientation, giving the “randomized” intensity (2θ) at various 2θ values. The on-line computer reads the scaler and timer every two degrees of x rotation and forms the appropriate integrals for calculating (2θ) as the sample rotates. Operation (c) is an extension of (b): not only is (2θ) determined, but also various moments of the orientation distribution of the form , where Pn is the nth order Legendre polynomial. Operation (d) may be used to measure pole figures of sheet specimens in reflection or transmission, or of fibers or small particles. Optional modes of operation allow for (a) use of the Ross “balanced filter” technique; (b) integration across diffraction peaks by continuous scanning in 2θ, with background correction; and (c) application of absorption corrections.
Measurement of Thin Oxide Surface Film Thicknesses and Atomic Densities by the Analysis of Positive Ion Excited Soft X-Ray Spectral
Authors: Saylor W. P. , Marks C. L.
Published: March 2019

Characteristic soft x-ray emission lines created as a result of low energy (10-100keV) positive ion excitation of a target material has been applied to the study of thin films of oxygen that form naturally on metal surfaces. The specific metals investigated were aluminum and nickel aa well as a number of their corresponding alloys.

Low energy positive ions are well suited as projectiles for the study of thin films in that they have low penetrating powers, yet produce high x-ray yields for K-, L-, and M-shell elemental x-ray lines. Perhaps the most important feature is the fact that no background bremsstrahlung continuum x-radiation is generated in the slowing processes of the ions. Exploiting the advantages of these facts, a special high sensitivity detection technique has been developed for the soft x-ray analysis of the constituents that make up a particular thin surface film.

The physical basis for thickness and atomic density measurements of thin surface films by positive ion excitation are discussed. Calibration data are presented for thin films of known thickness and composition establishing the sensitivity of the method for the measurement of the elemental atomic densities of thin films down to a few monolayers or approximately 10 Å in thickness. Finally, the results of the analysis of oxide surface films of aluminum, nickel and some of their alloys are presented and discussed.

The objective of this continuing program is to gain an understanding of the mechanisms and principles governing the formation of oxide surface films on metals with the basic goal of producing new alloying techniques for metal passification in a saline environment.
Solid Solutions of Cadium Sulfide-Cadium Selenide Films: Preparation and Determination by X-Ray Flourescence Method*
Authors: Chan Frank L. , Carpenter James T.
Published: March 2019

Solid solutions of cadmium sulf ide and cadmium selenide prepared by several methods at temperature in excess of 1000°C in inert atmosphere are described. The compositions of these solid solutions varied widely, ranging from pure cadmium sulfide to pure cadmium selenide.

Films of solid solutions have been successfully prepared by the vacuum deposition on various substrates using a procedure previously reported. Conditions for the depositions have been investigated to prevent noticeable alteration of the composition of the solid solution dur ing vacuum deposit ion. Films of various thicknesses have been prepared to date.

Determination of film thicknesses have been carried out by the fluorescence method based on the elements existing in these solid solutions. Chemical analysis in which specimens were consumed have also been used primarily for the construction of calibration curves. X-ray fluorescence intensity versus film thickness are established for films of 0, 25, 50, 77, and 100 percent by weight of cadmium selenide up to 10.00 microns thick on aluminum substrates. Thickness determinations using selenium Kαand cadmium Kαspectra give accuracies of 0.200 ± 0.05 to 10.00 ± 0.40 microns depending on film thickness and composition. Correction factors are given for films on substrates other than aluminum.

Procedures have been established for the determinat ion of both composition and film thickness based on fluorescence intensity data. There is a relationship between the fluorescence intensity and appearance when deposited films are not of the same thickness. Correlation of these phenomena will be demonstrated.
Some Applications of Energy Dispersive X-Ray Fluorescence Analysis in Minerals Exploration, Mining and Process Control
Authors: Clayton C.G. , Packer T.W.
Published: March 2019

Energy dispersive X-ray fluorescence (EDXRF) analysis is finding increasing application in field assay of soils and stream sediments for geochemical prospecting; in borehole logging and core analysis for formation evaluation in mine control, and in on stream analysis for process control.

The analytical capability of the method is determined by the choice of source, the energy of the exciting radiation and the energy resolution of the detector. The nature of the samples, their atomic number and concentration are also important. However, the most dominant constraints on limits of detection are often imposed by the environment at the region of measurement: by the borehole condition, the nature of the rock face or the form of the particulates and stability of the fluid in a process stream.
X-Ray Study of the Band Structure in Stannic Oxide
Authors: Bahgat A. A. , Das Gupta K.
Published: March 2019

In this article we present the experimental data on L3-absorption spectra of metallic tin. and tin in SnO2 . We have used (i) a bent crystal spectrometer and (ii) a high resolution flat crystal spectrometer with a microfocus target as the source for the continuum radiation. We have observed a “white line” on the low energy side of the primary L3-absorption edge of Sn in SnO2. Similar “white lines” in absorption spectra were reported earlier by M. Siegbahn in rare earth elements with f-vancies, who designated such lines appearing immedlately on the low energy side of the primary absorption edge as “white lines” in absorption spectra. It is interesting to note that metallic tin does not reveal the “white line”, while Sn in SnO2 clearly revealed a sharp white line on the low energy side of the primary absorption edge.
A Computer Aided Search/Match System for Qualitative Powder Diffractometry
Authors: Jenkins Ron , Hahm Y. , Pearlman S. , Schreiner W. N.
Published: March 2019

The use of the computer controlled powder diffractometer for the qualitative and quantitative analysis of multi phase powder mixtures is becoming relatively common place, and we ourselves have described in some detail the hardware and software components of typical systems 1,2) of which the AFD 3600 is the latest version 3). Although great success has been achieved in the use of the minicomputer for machine control, data acquisition and display, plus some degree of data workup, less success has been gained in search/matching of unknown powder patterns, although computer programs have been available for a number of years which utilize relatively large computers for automatic search/matching e.g. 4,5) the success with which these programs have been applied has been somewhat disappointing. Much of the difficulty arises from the marginal quality of data in the JCPDS index and from uncertainties in the accuracy of the experimental patterns.
Problems Associated with Kα Doublet in Residual Stress Measurements
Authors: Gupta S. K. , Cullity B. D.
Published: March 2019

Since the measurement of residual stress by X-ray diffraction techniques is dependent on the difference in angle of a diffraction peak maximum when the sample is examined consecutively with its surface at two different angles to the diffracting planes, it is important that these diffraction angles be obtained precisely, preferably with an accuracy of ± 0.01 deg. 2θ. Similar accuracy is desired in precise lattice parameter determination. In such measurements, it is imperative that the diffractometer be well-aligned. It is in the context of diffractometer alignment with the aid of a silicon powder standard free of residual stress that the diffraction peak analysis techniques described here have been developed, preparatory to residual stress determinations.
The Fitting of Powder Diffraction Profiles to Ananalytical Express Ion and the Influence of Line Broadening Factors
Authors: Brown Allan , Edmonds J. W.
Published: March 2019

Powder diffraction profiles of well crystallized compounds can be fitted to distributions of the type Iθ=I°(1 + k2x2)-n where k is a scale factor related to the half width of the profile. The value of n varies with the diffraction angle, 2θ, and is generally different for the low-angle and high-angle sides of the same profile. Limiting values of n for a specific Guinier camera-micro-densitometer combination are 1.2 ≤ n ≤ 2.3. Similar values are obtained for diffracto meter profiles after Ktt2 stripping. Line broadening due to departure from perfect crystallinity in the specimen affects the value of n a swell as that of k.

The above observations are interpreted interms of the convolution of a Gaussian with a Lorentzian distribution, the exponent n of the convolute being dependent upon the relative half widths of these two functions, expressed as the ratio bL/bG.
A Pinhole Camera for Photographing X-Rays from Laser-Produced Plasmas*
Authors: Hohlfelder J. J. , Palmer M. A.
Published: March 2019

A pinhole camera has been used to record low-energy x rays produced from CD2 microsphere irradiation with Sandia Laboratories four-beam, pulsed laser system. Camera useful energy range, spatial resolution, and x-ray energy sensitivity are discussed. Camera x-ray energy sensitivity which was determined by laboratory calibration is compared with measurements obtained with a multi-channel x-ray spectrometer. X-ray photographs of laser-irradiated microspheres are presented. Spatial information about the x-ray source derived from these photographs is discussed.
Low Energy X-Ray Microradioghaphy of Laser Fusion Targets
Authors: Prevender T. S. , Lynch A. W.
Published: March 2019

A low energy x-ray radiography apparatus has been developed primarily for the nondestructive inspection of LiD laser fusion targets. Exposure times of 15 minutes at 6 keV have been found satisfactory for the detection of voids in nominal 100 micron diameter spheres.
Math Model Design for X-Ray Analysis of Iron Base Alloys
Authors: Dryer H. T. , Appelman T. A.
Published: March 2019

An analytical system has been defined and developed which provides the x-ray analysis of iron base alloys (metal samples) corrected for an absorption, secondary fluorescence and interference effects. The analytical system provides for the transfer of analytical data and curves from basic or reference instrument to each new installation. One of the specifications for this system is the stringent accuracy requirements of the production analytical laboratory. Two major advantages of this system are:

(1)

The reduction of operator error because no decision is required for alloy identification,

(2)

A minimum of time required for new instrument calibration by the use of the analytical transfer procedure.
Measurement of Anisotropic Compressibilities by a Single Crystal Diffractometer Method*
Authors: Mauer F. A. , Hubbard C. R. , Piermarini G. J. , Block S.
Published: March 2019

The beryllium diamond-anvil pressure cell described by Weir, Piermarini and Block has been mounted on a Bond diffractometer equipped with an orienter of the fixed-x type. Molybdenum radiation is used to penetrate the diamonds and beryllium of which the cell is constructed, and special techniques are required to retain adequate precision in measuring cell parameters using diffraction angles in the low 2θ range. The method described provides high sensitivity in determining peak positions and eliminates the effect of centering errors on measured values of 2θ. Under favorable conditions, diffraction angles are measured with an accuracy of ±0.001° in 2θ. The method has been tested by measuring the lattice parameter of vacuum float zone refined silicon. Measurements of the compressibilities of silicon and of α-Pb(N3)2 (orthorhombic) have been carried out using the method of Barnett, Block, and Piermarini to determine pressure by measuring the shift in the R-line fluorescence spectrum of ruby.
The Pseudo-Kossel Technique in Back Reflection as a Tool for Measuring Strains
Authors: Berg H. M. , Hall E. L.
Published: March 2019

The back reflection x-ray divergent beam technique is examined as a tool for studying elastic strains. In particular, a method of calculating interplanar spacings using a least squares fit of experimental "conic" coordinates to Newman's general equation for back reflection (J. Appl. Cryst. 3 (1970) 191) is described. Using this technique, interplanar spacings can be obtained from partial conies. To determine the precision of this method an unstrained silicon single crystal is studied, and the errors associated with determining its interplanar spacings are discussed. The technique is then applied to elastically strained silicon and the results compared to theoretical predictions. It is shown that strains down to 2 × 10−5 are readily measured on high angle planes in silicon.
Self Absorption Corrections for X-Ray Fluorescence Analysis of Aerosols
Authors: Dzubay T. G. , Nelson R. O.
Published: March 2019

A procedure is described for making self absorption corrections for x-ray fluorescence analysis of ambient air aerosols which are collected in two size ranges with a dichotomous sampler. Calculations for fine particles are based on the assumption of a uniform layer of accumulated deposit which has an exponentially decreasing depth profile within a membrane filter. Coarse particles are treated as spheres with a log normal mass distribution which is subject to modification by the sampling device. An average attenuation and the associated uncertainty is deduced for coarse particles by considering a wide variety of possible chemical compositions.