bluuebunny/crossref_metadata_2025 huggingface dataset:
Sodium and Magnesium Fluorescence Analysis—Part II: Application to Silicates
Authors: Baird A. K. , McIntyre D. B. , Welday E. E.
Published: March 2019

Moderate counting rates, in excess of 400 cps at a signal/noise ratio of 18 on 3.5% NaaO in rocks, permit high-precision quantitative analysis for light elements in silicates. Special advantages of fluorescence analysis in the 10 A region, with adequate excitation provided by an aluminum target tube, will be described. These advantages include an ease of discrimination by excitation potential and by high dispersion using large 2d space crystals. Minor and simple modifications of the optic path combined with electronic discrimination make the method ideal for sodium and magnesium. Routine runs over periods of days have been made possible by a new technique of calibration involving computer corrections for systematic drift from any source. Repeated tests show that the total analytical error, including specimen preparation, closely approaches that of the counting statistics used, and that the drift corrections are complete. In granitic rod; analyses resulting precisions (standard deviation/mean) are 1% for 2-5% Na2O and 2% for 0.25-1.0% MgO.
Determination of Catalyst Residues in Polyolefins by X-Ray Emission Spectroscopy
Authors: Smith G. D. , Maute R. L.
Published: March 2019

X-ray fluorescence methods for the direct determination of aluminum, chlorine, titanium, and iron in polyolefins have been developed. The procedures require no preconccntration of elements, are satisfactory for any polyolefin, and are free from matrix effects. The accuracy and precision are generally comparable with or better than chemical procedures. In addition, the speed of the analysis is six to eight times faster.
X-Ray Analysis of Mining and Mineral Processing Material
Authors: Dryer H. T.
Published: March 2019

The X-ray analysis of the materials associated with the mining and mineral processing industries offers a wide variety of potential applications and a challenge to the X-ray analyst. X-ray methods are rapid, reproducible and, when suitably applied, accurate for elements of atomic number 12 or greater. These characteristics make it an ideal process control system. In general, the materials for each type of process require individual analytical techniques to provide reliable analytical data. A wide variety of materials have been studied on the ARL Vacuum X-ray Quantometer and their performances evaluated. An evaluation of the sample preparation and analytical methods required are given.
Increasing the Versatility of the G. E. Diffractometer
Authors: Schwartz L. H. , Morrison L. A. , Cohen J. B.
Published: March 2019

To achieve increased case and precision of alignment, and to allow for convenient alteration between normal usage with filtered radiation and crystalmonochromated radiation, the G. E. goniometer has been mounted on milling machine beds allowing for x-y translation and 360° rotation; in addition the tube mount was repositioned. The usefulness of this apparatus has been demonstrated by accurately aligning the goniometer for usage with filtered radiation, with a new alignment procedure. As a demonstration of the accuracy and precision of alignment, the lattice parameter of silicon was determined from a powder sample. A least-squares analysis of the data gave a0 = 5.43046 Å with a standard deviation of ±0.00005 Å, in excellent agreement with the value of 5.43054 ± 0.00017 Å determined in a recent International Union of Crystallography test in many laboratories.

A monochromator housing has been built for use with all types of direct-beam monochromators and all radiations. This apparatus attaches to the new tube mount and was used to determine the optimum procedure for preparing the doubly bent LiF monochromator crystals designed by Warren to minimize the volume sampled in the reciprocal space of a single crystal. According to a suggestion made by Chipman, a doubly bent monochromator for use with poly crystalline specimens has been formed and its geometry and applications are presented. This monochromator gives about one-half as much intensity as that obtainable using filtered radiation and similar operating conditions ; this type of monochromator is therefore a powerful tool for use with powder specimens. A transmission diffracted-beam monochromator has also been constructed which attaches in a simple manner under the counter tube housing. Under similar operating conditions with a LiF monochromator, this yields intensities only one-tenth of those obtained using filtered radiation.
An X-Ray Absorption Method for Elemental Analysis
Authors: Knapp K. T. , Lindahl R. H. , Mabis A. J.
Published: March 2019

A new approach to X-ray absorption analysis is presented in this paper. The equation log (I2/I1) = KWA + KB is used, from which the weight fraction WA of a given element can be calculated in various solvents when only a calibration curve from one solvent and the absorption of the new solvent at two wavelengths (λ1 and λ2) are known.

This treatment uses the absorption at two wavelengths, one on each side of an absorption edge of the element under study. The desired wavelengths can be conveniently obtained from the Kα and Kβ radiation of an element with an atomic number just higher than the element under study. An easy way to accomplish this is to use the desired target element as the sample in an X-ray spectrometer. The Kα and Kβ radiations are then resolved with an appropriate analyzing crystal, and the absorption measurements are made consecutively.

The advantages of this approach are twofold. First, it is only necessary to do a full calibration curve in one solvent; calibration in other solvents can be calculated with only a knowledge of the absorption of that pure solvent at the wavelengths used, which can. either be determined experimentally or calculated. Secondly, the required experimental data can be collected very conveniently in an X-ray spectrometer.
Application of a Pulsed Soft X-Ray System to the Determination of Phosphor Response Characteristics
Authors: McCue James C.
Published: March 2019

A compact, high-intensity pulsed soft X-ray system has been used to study the response characteristics of a plastic scintillation phosphor (NE-102). In particular, the decay characteristics of this phosphor plated on one surface with a thin (<1000 Å) layer of aluminum were investigated. Although, absolute calibration of the X-ray source had not been performed, estimates of X-ray scintillation efficiency were obtained, using two separate methods, which were in agreement to within a factor of two.

The primary purpose of this cursory program was to establish the validity of transferring calibration data from plated to unplated NE-102 scintillators employed in a photometric recording system. The results of the ensuing investigation indicated the equivalence of the two, but revealed several interesting and unsuspected phenomena. These were (1) an apparent scintillation light reflectance component of zero from the plated aluminum “mirror” surface, (2) a change in pulse waveform from electron beam input to scintillation light output, and (3) a 90-nsec delay between electron beam and photomultiplier signals. The methods employed in obtaining and verifying these data are subject to errors from uncertainty in the characteristics of several components employed in the experimental setup. These uncertainties and other measurement errors caused independent estimates of the external scintillation light efficiency to range from 0.1 to 0.2 %.

Other potential applications of a pulsed soft X-ray system to measurement problems in industry and research include dynamic studies in the fields of X-ray crystallography, instrumental methods of materials analysis, and radiography of low-density subjects.
The Use of a Portable X-Ray Unit for Measuring Residual Stresses in Aluminum, Titanium, and Steel Alloys
Authors: Bolstad Donald A. , Quist William E.
Published: March 2019

The principles of measuring surface stresses in metals by X-ray diffraction with commercially available equipment are well known. Two techniques of making stress measurement by X-ray diffraction now in general use are (1) X-ray diffractometer with electronic control panel and (2) back-reflection film camera.

The X-ray diffractometer technique has a number of important advantages over the film method, the major ones being accuracy and speed, but serious size and shape limitations are imposed on the specimen by the equipment: Because of its bulk and weight, specimens must be brought to it. The Airplane Division of The Boeing Company has capitalized on the advantages offered by the mobile backreflection film technique, especially with regard to specimen sizes and shapes. Results and techniques used, at Boeing for stress measurements in alloys of aluminum, titanium, and steel are presented. Experimental difficulties are discussed, and comparisons are made between results from the dirfractometer and backreflection camera, A portable darkroom and electropolishing unit are also presented which, with the X-ray unit, comprise a completely mobile stress-measuring facility.
A Study of Defects Due to Surface Processing in Silicon by Means of X-Ray Extinction Contrast Topography
Authors: Meieran E. S. , Lemons K. E.
Published: March 2019

In order to study the effects of processing variables on the defect contents of silicon wafers, an X-ray extinction contrast camera was designed and constructed to fit on the standard GE XRD-5 table. The camera, in its normal operating position, can be routinely used without interfering with the emission or diffraction instrumentation of the unit, and also can be mounted on the diffractometer stage for diffraction line breadth analysis. Routine laboratory procedures including sample preparation and mounting, film types, and film exposure and development are outlined.

The correlation between extinction contrast topographs and optical photographs of sawed wafers is presented. Wafers were examined in the sawed, lapped, and chemically polished conditions. Subsequent to each processing step in the surface treatment of wafers, a series of topographs was made using four different crystal orientations. In this manner the three-dimensional picture of the defects is obtained, as are the Burger's vectors of all dislocations. It appears that internal defects such as dislocations are more uniformly distributed in lapped and chemically polished wafers than in sawed and chemically polished wafers. Furthermore, different doping impurities and levels cause different amounts of contrast in the dislocation images.
High-Temperature Modifications of Thorium Dicarbide
Authors: Gantzel P. K. , Langer S. , Baldwin N. L. , Kester F. L.
Published: March 2019

Thermal analyses of samples of thorium dicarbide in equilibrium with graphite show arrests which indicate phase transitions at 1427 ± 21°C arid 1481 ± 28°C. These thermal effects have been observed on heating and cooling both in standard thermal analysis and in differential thermal analysis using graphite as a reference material. The microstructure of thorium dicarbide samples shows the characteristic “herringbone” pattern of a material which has undergone a martensitic-type transition.

A high-temperature X-ray investigation has revealed that the observed thermal arrests correspond to erystallographic transformations. The monodinic modification found at room temperature is stable to 1427°C, at which temperature a tetragonal modification with a0 = 4.235 ± 0.002Å and c0 = 5.408 ± 0.002Å is formed. At 1481°C, the tetragonal is transformed to cubic with a0 = 5.809 ± 0.002 Å. The best agreement between observed and calculated intensities has been obtained with C-C units of 1.5-Å assumed bond length in space groups P42/mmc and Pa3 for the tetragonal and cubic modifications, respectively.
Escape Peaks in X-Ray Diffractometry*
Authors: Parrish William
Published: March 2019

Escape peaks occur when the incident X-ray quantum, energy exceeds the absorption edge energy of the detector element and the resulting X-ray fluorescence is lost from the detector. The most common escape peaks result from 1 K-fluorescence in NaI-scintillation counters and Xe K-, Xe L-, and Kr K-fluorescence in proportional counters. The average pulse amplitude of the escape peak is proportional to the difference of the Energies of the incident and fluorescent X-rays. If the intensity of the escape peak is high as in the case of Mo Kα and a kryptoopreportional counter, and the lower level of the pulse height analyzer is raised to reject the escape peak, the quantum counting efficiency may be reduced by a factor of two. When the pulse height analyzer is set for characteristic incident radiation, escape peaks appear in powder patterns at small diffraction angles. These broad low-intensity peaks are often mistakenly identified as resulting from misalignment, scattering, etc. Each powder reflection can produce its own escape peak which occurs at an angle slightly smaller than the absorption edge of the detector element. In a silicon powder pattern the three strongest reflections produce three resolved escape peaks whose peak intensities are about 4% of their corresponding Cu Kα peaks when the X-ray tube is operated at 50 kV. The escape peak intensities decrease with decreasing X-ray tube voltage and disappear when the voltage is lower than the absorption edge energy of the detector element. Absorption edge peaks observed without the upper level of the pulse height analyzer are similar in appearance, intensity, and diffraction angle to the escape peaks. In complex powder patterns the escape peak pattern is unresolved and may produce a number of very broad peaks.
A Computer Program for Determining Accurate Parameters from Powder Data
Authors: Elliott Rodney P.
Published: March 2019

An IBM 7090 computer program has been written to determine precise lattice parameters for cubic, tetragonal, orthorhombic, and hexagonal systems. Leastsquares analysis is made with data fitted to the equation

where E is the eccentricity and A. is the absorption-divergence error. The computer program will make the least-squares analysis with neither, either, or both of the error(s) included. Data can then be reprocessed for other combinations of errors. After having determined the lattice parameter(s), on request, the computer program will predict the interplanar spacings, including the errors, so that observed data in the high-angle region may be indexed by comparison. Use of the program indicates that the most consistently reproducible parameters are obtained using only A, the absorption—divergence error.
Modification of Collagen and Nylon Lattices by Resorcinol
Authors: Shaw E. H. , Christensen Alton R.
Published: March 2019

By soaking formalinized rat-tail tendons in 2 M resorcinol, the tendon lattice is expanded equatorially from an interplanar spacing of 11.7 Å to 14.5 Å, indicating a diameter of 7.2 Å for the spiral core of collagen. Resorcinol distorts the lattice of nylon (6:6), converting the normal triclinic cell to an orthorhombic cell whose a and b axes are approximately four times those of the original nylon and whose c axis is reduced from 17.2 to 16.5 Å.
X-Ray Generation by Proton Bombardment
Authors: Sterk Andrew A.
Published: March 2019

Some of the characteristics of X-ray generation by proton bombardment are described. With work still in progress, it has been proven that this method is particularly suitable for soft X-rays >10 Å. Excitation efficiencies equal or excel electron excitation efficiencies, while the resulting spectrum consists of a single characteristic radiation line, but with complete absence of bremsstrahlung. Experimental results, the design of an instrument, and some applications are discussed.
A Compilation of Beta-Ray Stimulated X-Ray Spectra
Authors: Preuss L. E. , Collins H. , Wilson E. R.
Published: March 2019

The photons resulting from the interaction of beta particles and matter have a certain complexity of origin; but the spectrum is made up, in large part, of two primary components, one of these being the white radiation continuum produced by the external bremsstrahlung mechanism of beta acceleration at the target atom. The second fraction consists of the characteristic K and L X-rays of the target atom. Published beta-excited X-ray spectra are centered about a small fraction of the available pure beta emitters and a restricted group of target materials. Furthermore, intercomparisons between references are difficult, due to an infinite variety of source and detector parameters influencing the data.

This laboratory has begun a comprehensive reference compilation of these spectra, done on a comparative basis and simplified and standardized for sensible cataloging and easy reproduction of the experimental design. The prime purpose is to make available coherent data for many beta-excited X-ray sources in which beta activities, target geometries, and other critical parameters are known, controlled, and constant. Spectral sets for given source-target combinations may, therefore, be intercompared, and application of the beta-excited X-ray may be made with the best possible source-target atom combination.

The spectra are studied by three proportional counters (operating down to the 1 kV energy range) and two standard scintillation crystals, accumulated in a 256-channel analyzer, and are presented in sets (representing one beta source-target combination) consisting of a minimum of eight spectra, six of which represent the most critical transmission target geometry.

Examples of the cataloging of the spectral sets, for the mixture, apposition, and compound isotopic X-ray sources, are presented.
An Instrument for Soft X-Ray Selected-Area Microdiffraction*
Authors: Pattee H. H.
Published: March 2019

An instrument for soft X-ray selected-area microd infraction has been constructed fulfilling the principles of optimum intensity for given specimen size and resolution, and permitting direct visual beam focusing and alignment for specimen sizes in the 1-10 μ region. The X-ray source is a modified, two-lens, microfocus tube manufactured by Canal Industrial Corporation supplemented by a camera, specimen stage, and incident-light microscope. Target-to-film distance may be adjusted from 50 μ to several millimeters which allows the use of wavelengths as long as Al K radiation in air. The use of soft radiation for microsamples simplifies the collimation requirements and permits shorter specimen-to-film distance for a given resolution. Collimating apertures are punched in foil with etched tungsten points or with the microfocus electron beam. Results confirm the prediction that microsamples do not require excessive exposure times using optimum geometry for source size and camera dimensions.
Some Notes on Ultrasoft X-Ray Fluorescence Analysis—10 to 100 Å Region*
Authors: Henke Burton L.
Published: March 2019

Methods and instrumentation have heen developed for the extension of X-ray fluorescence analysis into the light element region, magnesium through beryllium. Examples of current values for the minimum detectable limits for these elements and associated instrumental parameters are presented. Some specific techniques are described for the use of an ultrasoft X-ray vacuum spectrograph, for the development of large d-spacing multilayer analyzers, and for the construction of thin window systems.
Preliminary Studies on the Characterization of Solution-Grown ADP Crystals
Authors: Deslattes Richard D. , Torgesen John L. , Paretzkin Boris , Horton Avery T.
Published: March 2019

Large single crystals of ammonium dihydrogen phosphate (ADP) have been grown from solutions of reagent grade materials by means of precisely controlled temperature programs. We have studied the perfection of these crystals by means of double-crystal rocking curves and diffraction topographs. In the course of this study, effects associated with various techniques of sectioning and polishing specimens from these crystals were examined. A combination of string sawing and chemical polishing procedures produced specimens exhibiting the best diffraction characteristics. Results obtained from surfaces so prepared are tentatively taken as being characteristic of the bulk crystal and may be interpreted in terms of longrange strain fields and imaging of both emergent and nonemergent dislocations. In some specimens, regions of 1 cm2 or more have been found to be free of defect images and to have uniform reflectance.

The perfection of some specimen pairs and the intrinsic properties of certain reflections suggest their possible application to spectroscopic problems. Some crystal pairs cut parallel to (101) planes have exhibited physical resolving powers of 104 at 8.3 Å; others cut for the 600 reflection have given 4 x 105 at 1,5 Å, These crystals deteriorate on exposure to moist laboratory air and preservation techniques had to be employed.
The Diffraction of X-Rays by Multilayer Stearate Soap Films
Authors: Ehlert Ralph C.
Published: March 2019

The diffraction of X-rays by multilayer stearate soap films has been studied as a function of (a) the number of diffracting layers and (b) the bivalent metal present. Both “Y” and “X” type structures have been built and analyzed with Al and C Kα radiation. The measured diffraction efficiency is compared with that predicted theoretically and with that obtained from a single crystal such as potassium acid phthalate.
A Study of Homogeneity of Solid Solutions of Cadmium Sulfide and Cadmium Selenide by X-Ray Fluorescence*
Authors: Chan Frank L. , Brooks Donald A.
Published: March 2019

The homogeneity of solid solutions of cadmium selenide and cadmium sulfide has been investigated. Crystals of the solid solutions having different selenium contents were grown in the Aerospace Research Laboratories by the conventional methods as described in the earlier conferences. The composition of these solid solutions were analyzed chemically for their selenium content by a procedure perfected in the Aerospace Research Laboratories.

Crystals in the form of lumps were cut to optimum size suitable to be inserted into the commercially available sample holder. The selenium content of these crystals was ascertained by scanning the samples with stationary colljmators of small aperture. The spectrograph used for the present study was operated at 75 KVP and 50 mA. The target tube was constructed of molybdenum. The results from the chemical method were used to correlate the counts per second obtained from the X-ray spectrograph.
The Determination of Calcium in Uranium Ore Concentrates by X-Ray Fluorescence
Authors: Knoke D. R. , Waldron H. F.
Published: March 2019

Since the advent of vacuum and helium path X-ray spectrometers, and flow proportional counters, the determination of low-atomic-number elements by X-ray fluorescence has become relatively common for light-element matrices. However, there are no reports in the literature on the determination of the low atomic-number elements in a rnatrix approaching that of uranium. This paper describes the successful application of the vacuum path X-ray spectrometer for the determination of calcium in the range of 0.03 to 1.75% (on a U3O3 basis) in uranium ore concentrates. The procedure provides a 50% saving in analyst time, with no sacrifice of accuracy or precision, compared to the chemical method previously used. With a chromium target tube, the intensity of the calcium radiation is quite sufficient for accurate analyses even though the samples contain approximately 80% uranium. The heavy uranium matrix actually serves to minimize any absorption or enhancement effects that would normally be expected from the large number of impurities that are present in widely varied concentrations.

Samples are prepared by dissolving 1.8 g of concentrate in 10.0 g of Na2B4O7 at 1050°C and casting into a disk on a polished aluminum plate. The advantages of this preparation compared to the use of pelletised powders will be discussed. The Ca Kα-to-U Mγ ratio is used to minimize the1 effect of instrumental and sample variations and to provide a linear relation with respect to the calcium concentration on a U3O8 basis. Calibration standards are prepared by the addition of CaHPO4 to either pure U3O8 or a uranium ore concentrate of low residual calcium. Data obtained during routine application of this procedure will be presented.
X-Ray Fluorescence in Cotton Modification Research
Authors: Mitcham Donald , Piccolo Biagio , Tripp Verne W. , T. O’Connor Robert
Published: March 2019

The application of X-ray fluorescence to the qualitative and quantitative analysis of chemically modified cotton textile materials is described. The scope and flexibility of the technique have permitted the determination of more than 20 elements with, greatly reduced elapsed time compared with the corresponding spectroscopic or wet methods. Precautions to be observed in preparing standards are discussed. Results of the analysis of typical modifications and their significance in the development of cottons for specific uses are described.
Observations of G-P Zone Reversion in Al-Zn-Mg Alloys by Small-Angle X-Ray Scattering and Transmission Electron Microscopy
Authors: Gould R. W. , Starke E. A.
Published: March 2019

A study of the reversion process in Al-Zn-Mg alloys has been made using small-angle X-ray scattering and transmission electron microscopy techniques. The rate and mode of Guinier-Preston zone dissolutions was investigated as a function of magnesium content, prior zone radius, and reversion temperature. Results indicate that in this system the reversion process is characterized by the preferential dissolution of the smallest G-P zones present after cold aging with a corresponding decrease in the volume fraction of zones. The amount of reversion at a specific temperature is dependent on magnesium content, however, the rate of reversion is independent of magnesium content.
The Structure of the γ′-Phase in Nickel-Base Superalloys
Authors: Rosen S. , Sprang P. G.
Published: March 2019

Present day nickel-base superalloys are hardened in part by the precipitation of a phase which has variously been identified as Ni3Al, Ni3(Al, Ti) and γ′. X-ray diffraction techniques which include precision lattice parameter measurements, intensity measurements, and phase identification are used to define the structural and chemical relationships upon which this phase is based.

These relationships are developed from the following considerations: crystal chemistry and atomic size factors which relate binary Cu3Au-type T3B phases (e.g., Ni3Al) and ternary Perovskite-type T3BC2 carbide phases (e.g., Y3AlC), the determination of the number and kind of atoms in the unit cell of Ni3Al and certain ternary phases, the crystallographic relationship between the structure of Y3C and Y3AlC, and phase relations in certain quarternary alloys.

From these considerations it is shown that the γ′ phase may best be characterized as a Peiovskite-type carbide phase having the chemical formula TsBCx. A model of the γ′ structure is presented which indicates the position of the various atomic constituents based upon whether they are T or B elements. (An atomic component is considered of the T type if it is capable of substituting for nickel in 3, of the B type if it can replace the aluminum. The essential features of this model are: T and B elements form an ordered T3B lattice of the Cu3Au type ; carbon atoms are located only in octahedral holes in the centers of the Cu3Au-type cells thereby establishing Perovskite-type T3BC3 unit cells; the effective size of T and B atoms in the T3BC3 unit cell is the same: hyperstoichiometric alloys, (ratio of B atoms to T atoms greater than one) will contain B atoms at face-centered positions in addition to a small amount of equilibrium vacant sites; in all alloys aluminum will preferentially occupy the cube corners of the unit cell ; the amount of carbon which is soluble in T3BC3; at any particular temperature is determined both by the distribution of the elements which are carbide-formers and the elements manganese, iron and cobalt. This model accounts for microstructural changes which occur in some nickel-base superalloys as a function of temperature and composition.
Crystallographic Studies of NH4Cl—NH4Br Solid Solutions
Authors: Callanan Jane Edmund , Smith Norman O.
Published: March 2019

Both ammonium chloride and ammonium bromide undergo a transition, with rise in temperature, from an interpenetrating simple cubic (II) to a face-centered cubic (I) lattice at 183 and 137°C, respectively, and both the low- and high-temperature forms give a complete series of solid solutions. We have determined the lattice constants of the high-temperature solids at about 250° as a function of composition, and redetermined the lattice constants of the low-temperature solids at room temperature. The solutions were made by crystallization from water, followed by stirring in contact with mother liquor for at least three weeks at room temperature. Measurements were made with a Norelco- Philips diffractometer and recorder, with Cu Ko. radiation. For the high-temperature work, a simple, inexpensive heating apparatus was developed. The only previous data reported for the high-temperature forms are the lattice constants of the pure components given by Bartlett and Langmuir.

The low-temperature solutions showed negative deviations from Vegard's rule at both ends of the concentration range and a slight positive deviation elsewhere when high-angle data were used. The high-temperature solutions showed marked positive deviations from Vegard's rule over the whole compositions range. Values for the pure components agreed reasonably well with those of Bartlett and Langmuir.

The progress of the change II → I with time was followed for some of the solutions in the neighborhood of the transition temperature in an attempt to reveal the mechanism of the process.
Chemical Bonding and the Sulfur K X-Ray Spectrum
Authors: Wilbur D. W. , Gofman J. W.
Published: March 2019

An investigation has been made of the relative Kβ intensities in different chemical states of the sulfur atom using the Kα lines, with appropriate corrections, to provide the intensity standards. Both inorganic and organic compounds were included in the study. The data for each compound appear to be reliable to about ± 0.5%, while the whole series of compounds shows a variation greater than 20% in the corrected Kβ/Kα ratios. Energies were also measured, particularly the Kα energies, and their shifts were studied relative to the Kβ, intensity shifts. The work was done with a plane, single-crystal, helium-path spectrometer with proportional counter and pulse-height analysis for detection. The results are indicative of the usefulness of the method both in clarifying an uncertain chemical state and in studying the electronic structure of the bonded atom.
Determination of Interatomic Distances from X-Ray Absorption Fine Structure
Authors: Lytle F. W.
Published: March 2019

A pragmatic, easily applied theory of the extended X-ray absorption fine structure found on the high-energy side of absorption edges is developed. This simple model can be successfully applied to determinations of interatomic distances, and it accounts for differences in Kronig structure on different absorption edges in the same material. Quantitative agreement with experimental data is good.
Matrix and Particle Size Effects in Analyses of Light Elements, Zinc Through Oxygen, by Soft X-Ray Spectrometry
Authors: Madlem K. W.
Published: March 2019

With the development of soft X-ray sources by Henke, it is now possible to extend the range of quantitative analyses by X-ray spectrometry into the very light element range (magnesium through, boron). Techniques of specimen preparation, recognized as one of the most critical aspects of quantitative X-ray analysis in the heavier elemental ranges, present new problems, especially with the physically and chemically heterogeneous materials encountered in mineral and rock analysis. This paper presents the results of new tests extended into the light and very light element range. It is shown that most of the problems previously found are intensified as lower atomic number elements are considered; conditions of the specimen surface are critical and require precise control of particle size. In addition, significant absorption by relatively heavier elemental constituents, either in a separate phase or within the same phase, causes poor precision and is difficult to predict. Thus, the combination of matrix absorption within and between discrete phases, combined with the difficulty of grinding different phases to a uniform particle size, suggests that fusion techniques are required for hest precision. Without fusion, both scatter and bias are introduced through non-linear calibrations, with each calibration dependent upon specimen composition and particle size. It is concluded that only with nearly uniform specimens, where gross deviations are to be checked (e.g., process control) can ground rock powders be used with success in light element analyses.
Use of the Soft X-Ray Spectrograph and the Electron-Probe Microanalyzer for Determination of Elements Carbon Through Iron in Minerals and Rocks
Authors: Baird A. K. , Zenger D. H.
Published: March 2019

The major elements m common rocks are of low atomic number, but analyses of high precision are possible by soft X-ray spectrography if several grams of rock sample are available. The electron-probe microanalyzer is shown to complement this established method by permitting analyses of particles as small as 1 μ in diameter. This paper describes applications of these methods to the analysis of the major and minor elements of silicate, carbonate, and phosphate minerals and rocks.

Elements of particular interest are as follows : carbon in particles enclosed in carbonate rocks; oxygen, as the major constituent of the specimens; phosphorus in phosphatic nodules and apatites; manganese and iron, as colorations in fossil shells; and the group oxygen, sodium, magnesium, aluminum, silicon, potassium, calcium, and iron as complex segregations and zonations within single crystals of several mineral phases.

If the bulk composition of a rock is known, and also the chemistry of the constituent minerals, it is possible to compute quantitative minéralogie analyses of high precision. Thus, the combined use of soft X-ray spectrography and electronprobe microanalysis can provide quantitative chemical and mineralogicat information on the earth's crust on all scales from thousands of square miles (by means of appropriate sampling) down to the scale of 1 μ.
A “Windowless” X-Ray Fluorescence Tube and a High-Resolution Diffractometer
Authors: Walker George
Published: March 2019

A system is described whereby X-ray fluorescence analysis of elements below atomic number 19 (potassium) is undertaken with a “windowless” demountable X-ray tube. Comparison is made with 100-μ- and 30-μ-thick beryllium windows- Deflection plates are required before or behind the sample to eliminate scattered electrons. A high-resolution X-ray diffractometer is also described by making use of a fine focal line on the target. Burn-through due to localized heating on the target is eliminated by using a thermocouple arrangement.
The Application of Scanning Electron Microscopy and Energy Dispersive X-Ray Analysis to the Examination of Forensic Paint Samples
Authors: Wilson R. , Judd G.
Published: March 2019

Electron optics techniques have been applied to the examination of various evidence materials common to forensic science. Vehicular paint fragments, a common evidence material, possess topographical features suitable for SEM analysis and composition variations in the form of chemically distinct layers and surface contaminant particles which can be characterized using energy dispersive X-ray analysis. The ability to analyze paint samples in terms of both topography and composition presents the potential of an extremely valuable tool for forensic investigators.

Over thirty automotive paint samples from many sources were examined in this study, using either the secondary electron image of the SEM or the SEM image combined with concurrent X-ray analysis by an energy dispersive System. Topographical pictures and X-ray spectra were recorded and comparisons between samples were made. Additional characterization of specimens was attempted through the analysis of individual paint layers.

The data obtained was used to group the paint samples into categories used for identification of the sample source. This information is valuable to several types of criminal investigation.
New Results Obtained with a Regular XRF Spectrometer and a Portable Field Spectrometer, Equipped with a Cold Cathode Electron Tube
Authors: Sahores J.J. , Larribau E.P. , Mihura J.
Published: March 2019

The results presented here have been obtained with a regular Philips universal spectrometer, equipped with an irradiation tube radically different from those normally used. Since we have previously described this tube in past papers (1) (2) (3), we will therefore only briefly recall its principle.

When starting this research program, our aim was to make possible the analysis of very light elements from sodium to boron, for a regular fluorescence spectrometer, without any modification of the spectrometer itself. As a matter of fact, the tube that we developed enabled us to reach this goal, but, moreover it opened some other possibilities :

1) heavier elements could also be analysed

2) thanks to the very low electric power required by this tube, a portable spectrometer could be built for field use

3) since it allowed a very convenient study of low energy X-rays, we could easily measure energy levels of external electrons and thus study the influence of chemical or crystallographical structure on the X-ray spectrum.
Proportional Counter Parameters
Authors: Burek A. J. , Blake R. L.
Published: March 2019

A flow proportional counter for ultrasoft x-ray applications has been constructed and used to measure proportional counter parameters in the ultrasoft x-ray region at atmospheric and subatmospheric pressures for counting gases of P-10 and methane. We find that at atmospheric pressures the parametrization given by Zastawny for describing gas amplification in proportional counters applies and have measured values for the parameters for P-10 and methane. For subatmospheric pressures the Zastawny parameters are inadequate. A new parametrizatlon is required. In addition, the linearity of the detector for x-rays of energies of 15 KeV to 0.5 KeV was measured for pressures ranging from 750 Torr to 150 Torr and found to be excellent in all pressure regions.
In Vivo Analysis of Lipid-Protein Ratios in Human Muscle by Differential X-Ray Absorption Using 109Cd Photons
Authors: Preuss Luther E. , Bolin Frank P.
Published: March 2019

Tissue's two major components: lipid and protein, are of a primary importance, related as they are to the normal life states. Assay of protein and lipid (fat and lean) in vivo is of certain criticality in human disease states, such as wasting, edema, obesity and other dyscrasias involving body mass and fat-lean balance. Since the elemental composition of lipid and protein molecules differ in a significant and regular fashion, their mass absorption coefficients differ when radiation in the x-ray and lower energy gamma ray region is used. Two monochromatic photons, one in the 20 to 30 keV region, another in the 60 to 100 keV region, can be shown to exhibit an absorption ratio in a two component system of fat and lean which provides for a determination of the component mass ratios. Photons from x-ray machines and isotopic x- and gamma ray sources have been proposed for this. The radionuclide offers qualities of stability, small size and weight, portability, zero power consumption and, generally, a certain economy. The electron capture decay of 109Cd provides a gamma ray at 88 kilovolts and a daughter (Ag) Kα doublet at 22 keV. This fortuitous energy combination is advantageous in this differential absorptiometry. The 109Cd source provides for a stable geometry and calls for the simultaneous measurement of both photons by non-dispersive x-ray spectroscopic techniques. Ten mCi of 109Cd was incorporated into a sealed source, filtered for the silver Kβ1 x-ray (at 24. 942 keV) with 0. 1 mm palladium and collimated with a grazing aperture arrangement. Fat-lean tissue simulating standard samples three cm to ten cm in length and of various component ratios were studied. Component weight percent was determined using a function of the transmitted radiation. Determinations on water (the lean simulator) and polyethylene (the fat Simulator) as well as other materials produced absorption ratios concurring favorably with the known make-up of the Simulators.

In vitro dual beam analysis of muscle tissue samples showed a high degree of correlation with the results of ether lipid extractions. Using lipid extraction values as the standard, the x-ray absorptiometric technique produced percentage lipid levels averaging within 0. 5% of the extractions.

In vivo measurements of fat content of the triceps muscle area were compared with skinfold thickness measurements of the same area. Coefficient of correlation was 0. 88.
Miniature X-Ray Equipment for Diffraction and Fluorescence Analysis
Authors: Herglotz H. K.
Published: March 2019

Energy yields in the generafion of monochromatic X-rays by electron bombardment are poor and the utilization of X-rays is even more wasteful, particularly in X-ray diffraction. Only a small stereoangle of radiation issuing from a flat target passes through the collimator of a camera.

An end-window X-ray tube using a conical cavity as a target is more economical, since there is a finite probability of several excitation acts by one electron in the cavity. A major part of the radiation emerges from the tube in a stereoangle of ≈ 0.02 instead of 2π steradian. This and the proximity of the tube focus to the sample are favorable for X-ray diffraction, as will be demonstrated in several examples. The geometry and performance of the tube are also expected to provide a superior replacement for the weak isotopic sources normally used in energy dispersive analysis.

Several versions of the tube, covered by U.S. Patent 3,584,219, H. K. Herglotz and C. D. Reilly, are described. Of particular interesf for X-ray diffraction is a double cavity tube with 2 exit ports. The Iow power consumption of the tubes (35 kV, 1 mA or less) requires only a small power supply. All equipmenf for XRD work including batteries can be accommodated in a suitcase and therefore lends itself to field use by mineralogists, for example, or in materials testing.
A Rapid Fluorescence and Energy Powder Pattern Analysis System
Authors: Lin Wen
Published: March 2019

Reported here is a computer-coupled energy dispersive x-ray system capable of performing rapid elemental analysis and phase identification employing fluorescence and energy powder pattern analyses, The system consists of a Si(Li) detector, commercial diffractometer, vacuum specimen chamber with fluorescsnce geometry and a multichannel analyzer interfaced to a laboratory computer.

The continuous radiation is used to excite both fluorescent x-rays and Bragg reflections. The diffractometer spectrum obtained with a fixed 2θ setting gives the crystalline diffraction pattern plus the detectable emission lines. With the fluorescence geometry, the system is capable of detecting the characteristic x-rays of the elements down to Na. The fluorescent spectrum can be used to separate the diffraction peaks from the emission lines in the diffractometer spectrum. Furthermore, the fluorescent spectrum can be used for qualitative or/and quantitative elemental analysis.

Software was developed for element recognition, to isolate the diffraction pattern from emission lines, d-spacing calculations, as well as matrix corrections and mass fraction determination of elements in quantitative analysis.
Use of an Automated Powder Diffractometer for the Analysis of Rock Samples
Authors: Jenkins R. , Westberg R.G.
Published: March 2019

We have recently described an automated powder diffractometer, the APD-3500, in which a small (4K x 18 bit) minicomputer is utilized for hardware control and data processing. Among the software programs developed for this system is a “Peak Search“ routine which is designed to record a diffraction pattern with optimum, use of scanning time and to give output directly in J.C.P.D.S. Powder Data File Format. Optimum use of scanning time is achieved by a double-pass System in which a first (rapid) pass is made to establish significant data.

A second routine is a “Line Profile” routine which gives the choice of rapid slewing or slow Step scanning of the goniometer between selected angular ranges. The routine thus allows the controlled stepping of the goniometer between selected angular ranges giving incremental and integral, background corrected counts. An automatic internal and/or external calibration capability makes this particular mode ideal for quantitative analysis.
The Asymmetric Bragg Reflection and its Application in Double Diffractometry
Authors: Renninger M.
Published: March 2019

Guided by the dispersion, surface of dynamical theory, we easily obtain evidence of the fact that in asymmetrical surface reflections (Bragg case) of X-rays at a perfect crystal, the angular widths of the incident and reflected beams are different from the same widths in the symmetrical Bragg case. The beam with the smaller glancing angle to the surface is angularly expanded, the other one, contracted (though in cross section, the former is contracted and the latter, expanded). Consequently, if the incident glancing angle is the smaller one (striping incidence, Vreftection), the angular width of the reflected beam is smaller than in the symmetric case (S-reflection), and that of the reflected section out of the primary beam is greater, and vice versa (striping emergence, if-reflection). At striping incidence, a contraction occurs, whereas at striping emergence, expansion of the angular reflection range occurs. These facts offer a number of possibilities for applying asymmetrical reflections to the well-known technique of the two crystal diffractometer—the author proposes the term “diffractometer” instead of the widely used “spectrometer”—in the (nv, −n)-position. These possibilities extend the efficiency of the double diffractometer with multiple effects, and some of them are given below: (1) Realization of rocking curves of extremely small angular width in the (nv, −nR)-position, and consequently increased sensibility of that width to lattice distortions, (2) Use of the extremely small angular width (or more strictly, the sharp θ-λ-coordination) of the beam emerging from a first crystal. This is in V-reflection for scanning the intrinsic diffraction pattern of the second crystal used in S- or V-reflection [(nv, −ns) or (nv, −nv) -position], (3) Increased steepness of the sides of the rocking curves using (nv, −nR) or (nv, −ns)-positions which allows double diffractometric topography (Bond-Andrus, Bonse-Kappler) of increased angular resolving power. (4) Repeated ^-reflections (eventually within a single crystal provided with a suitable groove) leading to further angular contraction of the resulting reflected beam and therefore further increased angular resolving power [(nv, −nv, nR, −nR)- and (nv, −nv, +nS)-positions]. Here the tails of the rocking curve are also suppressed by multiple reflection (Bonse-Hart).
Experimental Determination of the Integrated Contribution of Temperature Diffuse Scattering in X-Ray Reflections
Authors: Renninger M.
Published: March 2019

A double diffractometric method which allows clean separation of the thermal diffuse contribution from X-ray reflection peaks is demonstrated.