Recent studies indicate that, if the stress/strain field within the irradiated volume in an x-ray stress determination experiment is inhomogeneous, oscillations occur in the interplanar spacing vs. sin2ψ plots. There is, however, little work on the degree of inhomogeneity required to cause a given oscillation, the uniqueness of the stress fields that can cause a given set of oscillations, or the error caused by applying the traditional methods currently in use to oscillatory data.

In this paper, numerical modeling and eiasto-plastic finite element analysis was used to determine the strain fields in the diffracting volume of a polycrystalline sample under load. The elastic strain fields obtained from the analysis were then averaged over the regions that would diffract in an x-ray experiment/and then correlated to x-ray strain data to obtain an idea of the problems described ahove.

The present paper describes an energy-dispersive x-ray fluorescence method for measuring tin in bis(tri-n-butyl)tin-oxide impregnated wood. The proposed method is of the backscatter/fundamental parameter type. Its versatility, precision, and accuracy is demonstrated by analyses of eleven samples of sapwood of Baltic Redwood. The results obtained are compared with those from neutron activation analysis.

Geological samples prepared for analysis by X-ray fluorescence (XRF) are particularly prone to intrasample and intersample phase variations creating significant inhomogeneity and variations in matrix effects. These features may “best be eliminated or diminished by fusion of the sample with, a suitable flux (1,2). Presentation to the X-ray spectrometer may be as a briquet of the comminuted fusion head (1,3,4,5) or as a molded glass disc or wafer (l,2,5,6). Because of the stability of glass discs and the necessity to eliminate possible contamination during grinding and making briquets, molded glass discs appear to be the best and easiest means of presentation.

This paper describes a computer method for wavelength dispersive (WD) qualitative X-ray fluorescence (XRF) analysis. It determines the elements, spectral lines, wavelengths, reflection angles and peak intensities of the first and second order reflections in less than half a minute of time using an IBM Series/1 minicomputer. The resolution and precision are significantly better than the energy dispersive (ED) method and when combined with high speed computer recording the speed is comparable.

A critical discussion of the equivalent wavelength representation of polychromatic primary radiation as applied to the fundamental parameters method is given. This representation raises problems with appropriate selection of equivalent wavelengths and with accurate calculation of secondary fluorescence. Methods for reducing these difficulties are discussed and have been incorporated into a mini-computer program which achieves reasonable accuracy for alloy test cases.

X-ray diffraction as a means of determining stresses has found increasing application in the last few years. This is primarily because it is the only technique by which stresses can be determined without making measurements on the specimen or structure in the unstressed condition and, consequently, it is the only truly nondestructive technique for determining residual stresses. The principles of determining macrostresses on surfaces with commercially available equipment is quite well known and employs either the X-ray diffractometer or back-reflect ion camera techniques. The diffractometer technique was selected for this investigation because of its accuracy and because it allows both macrostresses and microstra in to be analyzed from the change in position and shape of the diffraction peaks. The X-ray analysis actually consisted of two separate phases. The first dealt with the X-ray determination of the elastic constants (Young's modulus and Poisson 's ratio) for several aluminum alloys, including 5083. These values were compared with the theoretical or published values as determined by standard tensile tests and used later in stress calculations. For these tests, a unique stress stage was used which allowed the specimen to be stressed while positioned in the diffractometer, and also have angular rotation about the diffractometer axis that is independent of the rotation of the counter and receiving slit system. The second phase consisted of analyzing different groups of 5083—aluminum alloy specimens which had been subjected to various degrees of cold working by rolling. This analysis consisted not only of the computation of macrostresses, but also of microstrain and change in particle size as a function of percentage reduction in thickness. The final portion of this phase dealt with electro polishing successive layers from the surface of each sample and relating the measured relaxation to the thickness of the layers removed. In this way, stress distribution in depth was obtainable as a function of cold working.

The total reflection of X-rays is mainly determined by three parameters , that is the orltical angle, the reflectivity and the penetration depth. For X-ray fluorescence analysis the respective characteristic features can be exploited in two rather different fields of application. In the analysis of trace elements in samples placed as thin films on optical flats, detection limits as low as 2 pg or 0.05 ppb, respectively, have been obtained. In addition, a penetration depth in the nanometer regime renders Total Reflection XRF an inherently sensitive method for the elemental analysis of surfaces. This paper outlines the main physical and constructional parameters for instrumental design and quantitation in both branches of TXRF.

A new X-ray probe attachment for the standard Norelco Vacuum Spectrograph has been developed. The X-ray optical design is essentially the same as that of the Norelco/AMR Microprobe goniometer, being an Ogilvie-type varying curvature Johann focusing device. A light optical system which allows the examination of the specimen during analysis is incorporated in a prealigned module along with the X-ray beam defining aperture. This arrangement assures a constant relationship between beam and optical field centers. Apertures ranging in diameter from 50–500 μ are provided. Data are presented giving the effective size of the specimen area analyzed using each of these apertures. A detailed description of the component parts of the instrument is given.

White beam transmission topography was used to image defect structures in gallium arsenide single crystal substrates representative of those used for microwave integrated circuit fabrication. A scanning topographic camera was developed for Beamline X-19C at the National Synchrotron Light Source. Acquiring film topographs within a particular range of scan rates and x-ray fluxes was found to produce distorted images. The distortions were shown to be thermoelastic, arising from inhomogeneous deposition of thermal energy through the absorption of residual x-rays. The problem could be circumvented using faster scans with some sacrifice in spatial resolution. Real time electrooptic topographs were recorded using x-ray fluxes about one percent of those used for the film topographs. The potential for reducing the flux requirement to even lower levels which would be accessible to flash x-ray generators is considered.

The recently developed code SHAPE allows the build-up of EDXRF spectra for collimated and monochromatic excitation. In this work the code is applied to investigate the Importance of the scattering corrections to the more intense XRF characteristic lines from low and medium Z elements. Results are given graphically for pure elements from Z=11 (Na) to Z=42 (Mo). Heavier element lines from a multi-component geological sample, where light matrix amplifies the influence of scattering, are studied.

With modern X-ray instruments, precision is generally satisfactory for the analysis of MgO, Al2O3, SiO2, CaO, and Fe2O3 in finished and raw-mix cements and other similar materials. Accuracy, that is, agreement between cheraicaland X-ray values, quite frequently is much worse than precision. Some typical examples illustrating this point are reviewed.

In the soft region, generally, it has not been possible to assign the cause of iuaccuracy to interelement effects. The hypothesis is formulated that in the soft region this problem could be due to mineralogical differences and inhomogeneity on a micro scale. Theoretical calculations support the plausibility of this argument.

To improve accuracy, present techniques have been based on type standardization, acid digestion fusion using a high flux-to-sample ratio, etc. In general, these methods have certain basic limitations. In order to retain useful intensities and lineto- background ratios for the soft region, 8 new fusion technique has been developed. The experimental data based on this method of reducing micro-inhomogeneity and eliminating minaralogical differences indicate improvements in accuracy. In the case of finished cements the improvements in accuracy have been quite modest. With rawmix cements, startling improvements have been obtained for the analysis of SiO2 and CaO.

Ila group metal - Zr pcrovskitc type compounds (MZrO3, M=Ba. Sr and Ca) and other oxides were studied by XPS to know the effects of M atoms to Zr atoms. And the feasibility of using XPS and high-resolution XRF for the coordination analysis of Zr atoms was examined for some kinds of stabilized zirconia. An almost linear relationship between the energy of Zr 3d peaks and the radii of Ila group metal ions was found, and, a simple model to interpret this relationship has been proposed. However, no relationship between the energy shifts of Zr 3d spectra or Zr Lα1, 2 spectra and the coordination numbers of Zr atoms in the several Zr oxide compounds was found. Thus, the coordination analysis using XPS or high-resolution XRF is not feasible.

In view of the amount of data per time unit the scanning electron probe is capable of producing, time economy in data presentation is of great practical importance. In this paper, the characteristics and advantages of various previously known techniques of data presentation are described, and some novel procedures are proposed.

Recently developed, miniature, steady state, field emission tubes are finding application in several areas of x-ray analysis. These tubes require only a high voltage, low current power supply to produce relatively intense beams of x-rays. Since anodes can be fabricated from almost any element, and since the tubes can be operated at potentials up to about 70 kV, many different output x-ray spectra are available. Miniaturized battery operated x-ray sources of this type, occupying a volume of about one liter, have several advantages over radioisotope sources. These include cost, safety, and controllable output spectra and intensity. X-ray sources for energy dispersive fluorescence analyzers are designed so that no scattered characteristic radiations will interfer with the analysis of the sample fluorescence. Sources which are essentially monoenergetic can be fabricated for use in non-dispersive x-ray fluorescence analyzers. Because of the intensity and safety of the field emission tubes, such analyzers can be made which are sensitive while compact, portable, and inexpensive. In x-ray absorption analysis the measurement of absorption edge jump ratios provides a quantitative measure of sample impurities. Field emission tubes whose output spectra consist primarily of bremsstrahlung are particularly well suited to such measurements. The techniques involved in using these tubes in x-ray analysis are described.

Methods are described which make use of x-ray absorbing masks to either limit beam penetration in the sample (Type I), or confine the diffracting volume within definite limits (Type II). The masks consist of a metal film of Au or U, containing many long, parallel apertures of effective width w and spacing c. The mask is either applied directly to the sample surface (Type I), or to a weakly absorbing film (Be or Kapton) on the sample surface (Type II). With the Type I mask, the diffracting volume can be limited to a surface layer whose maximum depth zm at ψ=0 varies linearly with w, irrespective of sample or wavelength. The masks can be used with ψ-tilts in an Ω-type goniometer, and strains and stresses can be determined by the Sin2ψ method. Depth profiles as a function of depth z (z-profiles) can be obtained with layer removal if gradients over the depth Zm can be neglected. With the Type n mask, the diffracting volume can be limited to a discrete subsurface layer whose average depth depends on (c+w) and the Bragg angle 2θ, and whose thickness depends on w and 2θ. z-Profiles can be obtained by varying the wavelength for a given reflection using a synchrotron source, without the need for layer removal. The methods have not yet been tested experimentally.

The use of the Polychromator (multichannel spectrometer) for X-ray analysis allows choice of the optimum combination of slit width, crystal type, focussing circle radius and detector for each of the elements to be determined by the instrument.

Comparisons will be made of various curved and ground crystals such as quartz, lithium fluoride, sodium chloride and ADP used in a focussing spectrometer. The effect of the width of the entrance and exit slits upon resolution, line intensity and line-to-background ratios will be discussed. Gas filled detectors such as Multitrons, flow proportional counters and Geiger counters will be discussed as to the effect of the filling upon efficiency and upon their use with counting or integrating techniques. Limits of detectability for various elements with optimum combinations of the above components will be reported.

Phosphorite is a sedimentary rock with a high enough content of phosphate minerals to bo of economic Interest. Most phosphorites are composed predominantly of m1crocrystall1no to cryptocrystalline carbonate fluorapatlte thenceforth In this report referred to simply by the mineral group name apatite). Florida produces roughly 1/3 of the world's supply of phosphate rock, most of which is used 1n the fe rtiliz e r Industry.

Long term continuation of phosphorite mining In Florida will require exploitation of the extensive hlgh-magneslum phosphorite deposits south of the present mining d istrict 1n central Florida, and this will require new technology In order to produce beneficlated concentrates with less than 1% MgO, a limit Imposed by fe r tiliz e r processing technology. In order to develop benefication methods applicable to these ores, it is essential to know how Mg occurs in phosphorites. Dolomite, CaMg(C03)2, is the chief host of Mg In phosphorites from Florida. Magnesium may also be present, however, as a substituent In apatite (the chief phosphate.mineral in these deposits), as a minor substituent 1n calcite (CaCO3), in certain clay minerals (particularly palygorskite and to a lesser extent in some smectites), and/or in organic matter within the apatite particles.

Digitized data acquisition and subsequent peak-profile fitting are used in aligning and maintaining the Guinier diffraction system in this laboratory. Utilization of a stepping motor driven goniometer along with profile analysis allows rapid and reproducible alignment while providing a means to investigate the types and magnitudes of errors introduced by various misalignments of the optical system.

Several examples of time-resolved X-ray powder diffraction studies with linear position-sensitive proportional counters (PSPC) are described. The changing patterns are recorded by spectrum multiplexing in a multichannel counter device. The time resolution for single processes is limited to seconds or tenths of seconds mainly because of the counting statistics of the observed peaks. Repetitive processes, however, where the interesting peaks can be accumulated over a large number of periods, permit much higher time resolution. It is finally determined by the timing of a detected X-ray quantum. Using a continuous beam source like a conventional X-ray tube the incidence of a photon into the PSPC can be timed with an accuracy of 20 ns (fwhm). A pulsed synchrotron radiation source, like a storage ring, will be able to define this resolution to its pulse duration, which is less than 200 ps.

Before approaching those limits this paper presents the high temperature phase transformations in iron for different steel specimens as an example of single processes. It also discusses domain-wall effects and electrostriction in ferroelectric perovskites as a function of polarization at frequencies of up to 10 Hz, and elastic lattice distortions of a steel sheet vibrating at about 200 Hz. The timing limit of 20 ns for the PSPC detection system was measured at the storage ring DORIS at DESY, Hamburg.