A feasibility test at the Naval Research Laboratory has shown that a miniature X-ray Fluorescence (XRF) sensor can be constructed for the cone penetrometer. Such a sensor would have detection limits for heavy metal contaminants in soils of a few parts per million. The next step is to demonstrate the capabilities of such a sensor in the cone penetrometer. A sensor for this purpose is being constructed and will be tested both in the laboratory and in the field. The XRF sensor will be capable of evaluating the in-situ detection limits and field screening (semi-quantitative) capabilities of x-ray fluorescence and can be transitioned to field activities for further evaluation and feedback. The sensor will consist of a miniature x-ray tube and an x-ray detector, together with appropriate apertures and x-ray filters, in a custom fabricated section of penetrometer pipe. The sensor will use commercially available components. High voltage and signal cables will couple the sensor to electronics in the truck. Boron carbide will be used for the x-ray windows which protect the sensor components from soil abrasion.

X-ray fluorescence (XRF) has become a well established technique for the measurement of trace levels of toxic heavy metals in vivo, including cadmium, platinum, mercury and lead (Mattsson et al.. 1987). The clinical motivation for the measurement of platinum (Pt) is the need to investigate the kinetics of Pt-based cancer chemotherapy drugs such as cisplatin and paraplatin. Currently the main research interest in Swansea lies in the study of the uptake and distribution of Pt administered during chemotherapy of patients with tumours in the head and neck region.

The combined derivative method (accompanying paper) was tested with a large number of experimental patterns to illustrate its use in various difficult problems commonly arising in peak search analysis of X-ray diffraction data. Patterns obtained with various step sizes, resolution, counting statistical noise, and profile widths were used. The precision in 2θ determination and overlap resolution are in good agreement with those previously obtained from calculated profiles, raise identification of noise as diffraction peaks was eliminated by using a convolution range proportional to the full width at half maximum. Peak search results (both 2θ and intensity) were also compared to those obtained by profile fitting to illustrate the different characteristics of these two methods.

Several calibration methods and empirical formulae have been developed so far for analyzing materials quantitatively in XRF spectrometry. Many of them require reference samples to determine the relationship between the characteristic intensities of the elements and their concentrations. In order to eliminate empirical and semiempirical procedures, the fundamental parameter method (FPM) has been developed, which is one of the most helpful evaluating tools in quantitative XRF analysis. Some interpretations of this approach have the advantage that no standard samples are needed. The simultaneous application of FPM and polychromatic excitation demand an exact mathematical description of the primary spectral distribution as well as the efficiency function of the detector system.

The characterization of finely divided and structurally imperfect solids is required in the study of many classes of materials, e.g. ceramics, catalysts, decomposition products. Diffraction line broadening is influenced by the microstructure of the solid and is a valuable technique for a unique characterization of a material in terms of size and morphology of crystallites (a region over which diffraction is coherent) and imperfections (microstrains, d- spacing fluctuations, stacking faults, etc). The extraction of these features has traditionally been based on the study of individual diffraction lines, which restricts the analysis to a limited number of directions of diffraction vectors. The complexity of most powder patterns has been a serious impediment to the widespread use of the procedure for detailed microstructural characterization. The advent of fitting techniques, with the use of structural information (Rietveld method) and without structure model (pattern decomposition method) have extended the frontiers of diffraction line profile analyses. In the Rietveld method it has been recommended to have a prior knowledge of the origin and lattice direction dependences of the imperfection effect before embarking in the modelling of line broadening through the pattern. This modelling can be carried out with pattern decomposition methods, which provide individual diffraction lines for a subsequent study of microstructural properties. Several aspects of this technique, performances, limitations and practical problems are reviewed and discussed. Applications to oxides with high specific surface-area are used to illustrate the detailed microstructural information contained in a powder diffraction pattern.

In the event of an accident in a light water moderated nuclear plant, the fission products escape from the water moderator in form of gas bubbles. One of the most important fission products is Iodine. Presently there are only rough estimations of the escape of Iodine. The aim of the experiment planned at the Swiss Federal Institute for Reactor Research (EIR) is to simulate the conditions of an accident and to measure the amount of Iodine which escapes from the moderator water into the space inside the reactor containment.

It is supposed that at 5 m depth in a water pool, the canning of the fuel element explodes releasing 1-3 liter large gas bubbles containing the volatile fission products. The Iodine vapor concentration, saturated in the gas bubble, will be about 3 mg/l. It is expected that the water strongly absorbs the Iodine vapor and the I concentration in the gas bubble arriving at the water surface will be strongly reduced to a few ug/l.

Todays demand for rapid trace element analysis in pollution control and resource materials has led to the development of a completely automatic, very sensitive and stable Si(Li) X-ray analyzer. The key element, a transmission target tube, which has inherently a very clean monochromatic X-ray output, has been studied in view of efficiency, sensitivity and stability. The transmission target tube requires different operating criteria than conventional X-ray tubes. An analysis was made to “explain” these differences using fundamental X-ray physics. Studies included various experiments directly applied to practical problems in analysis of pollutants and mineral resource materials.

The chemical analyses of pigments and fillers are important to both the manufacturer and the papermaker. Most standard analytical methods, including those of Technical Association of the Paper and Pulp Industry, are based on the so-called classical gravimetric and volumetric techniques. The major components analyzed are TiO2, SiO2 and Al2O3 . X-ray diffraction methods are available for the identification of crystalline fillers and pigments in finished paper.

Thin film technology is rapidly evolving today, and the characterization of the thin film and its surface have become very important issue not only from scientific but also technological viewpoints. Although x-ray diffraction measurements have been used as suitable evaluation methods in crystallography studies, its application to the structural evaluation of the thin films, especially organic one having the low electron densities, is not easy due to the small amounts of scattering volume and the high obstructive scattering noise from the substrate. However, the x-ray diffraction measurements under grazing incidence will aid not only in overcoming the such problems but also in analyzing in-plane structure of the thin films. Therefore, so-called grazing incidence x-ray diffraction (GIXD) has been recognized as one of the most powerful tools for the surface and thin film studies.

The behavior of charged dislocations in alkali-halide crystals has been drawing attention in connection with the charge transfer which occurs during plastic deformation.1-9 Recently, Itagaki proposed a charged dislocation mechanism to account for the dielectric properties of ice.10 His theory is in part supported by the dielectric measurements o f strained ice made by Ackley and Itagaki.11 Brantley and Bauer12 derived similar equations for the dielectric constant based on charged dislocation motion. They also proposed a new mechanism for apparent piezoelectricity based on moving charged dislocations in an electric field .

A new approach to the analysis of preferred orientation in body centered cubic sheet materials is presented. The technique utilizes normalized extended inverse pole figures (2θ = 16 to 150°) taken in the plane normal, rolling, and transverse directions. Possible texture components are defined to be all unique sets of three mutually orthogonal crystallographic planes included in the diffraction pattern up to 150° 2θ for a total of 56 possible components. A computer program has been developed to calculate the contributions of various texture components relative to the three principal directions by two computer implemented algorithms, probability and successive decrementation. The two methods exhibit an apparent high correlation.

The calculated results are compared to monochromated direct pole figures for a highly textured material. The agreement is excellent.

Polarized x-rays are used to excite samples of any kind and shape to emit characteristic radiation. In the appropriate geometry, where source-sample-ED detector are in any orthogonal position to each other, the exciting poLarized x-rays will be practically not scattered from sample and substrate into the detector. This reduces the background considerably and hence improves the lower limits of detection. The production of intensive polarized x-rays is done by using a single crystal-where Bragg reflection occurs at an angle 2 θ = 90° instead of amorphous low Z scatterers. The result is a linear polarized and monochromatic beam. The use of curved crystals instead of plane single crystals further increases the intensity of the exciting radiation. The lower limits of detection attainable with the recently constructed compact polarizer device are in the sub ppm range or in absolute amounts around 150 pg for medium Z elements.

A simple method for high-resolution measurement of surface misorientation in electronic materials is introduced. The technique combines laser optical alignment with double-crystal x-ray diffraction to yield a typical sensitivity of better than 1-2 arc sec. The technique can also be used to make corrections in spectrometric measurements in which commonly ignored rocking - curve errors may be significant.

Two-dimensional detectors utilized in x-ray diffraction studies are described. Film, image intensifier/CCD camera, two-dimensional position-sensitive area, and photostimulable storage phosphor detectors are compared. The storage phosphor detector was found to be well suited for analysis of oriented semicrystalline polyester films. Quantitation of polymer orientation was determined using the Hermans orientation distribution function.

We describe a new X-ray fibre diffractometer, consisting of a commercial X-ray sensitive video camera coupled to a conventional 3-circle goniometer in place of a more traditional single-point detector. The active element of the video camera is a charge-coupled device (CCD). Diffraction images, obtained at various goniometer settings, are transformed into reciprocal space, and combined to give a complete section through the origin and parallel to the symmetry axis of cyiindrically averaged reciprocal space. A greater density of measurements is needed in the vicinity of the reciprocal fibre axis in order to avoid information loss due to the curvature of the Ewald sphere. The pros and cons of using CCD's as X-ray detectors are discussed and sample results from polymer fibres are shown.

Rat tail tendons were fixed in 4% formaldehyde at 250 g tension, soaked in nearly saturated solution of the amides involved, and dried while still under tension. X-ray diffraction patterns, taken with rotation around the collagen fiber axis, showed well-defined layer lines of the amide and usually substantial expansion of the collagen equatorial spacing.

The layer lines on collagen, in two cases on abnormal or polymorphic axes, are clustered around the number 4.86 ± 0.33 Å, or a figure twice this, implying the presence of a repeating hydro gen-bond accepting group such as the carbonyl group at this interval. The prominent collagen layer line at 9.4 Å is approximately double this interval.

Residual stress measurements were made on a ground rail steel (0.75 %C) using the newly developed ϕ-integral method and the conventional ψ-differential method. The strains <εϕψ> were measured as a function of the azimuth angle ϕ, the angle of rotation about an axis perpendicular to the specimen surface, from 0° to 360° in steps of 15°, at fixed tilt angles ψ, the angle between the normals to the specimen surface and the reflecting planes (hkl), set between 0° and 45° in steps of 9°.

It was found that <εϕψ> plotted as a function of ϕ is not periodic with the period of 180° and consequently exhibits the so-called ψ-splitting when plotted as a function of sin2ψ at constant ϕ. The Fourier coefficients of the function <εϕψ> plotted versus ϕ were used to evaluate the strain tensor <εij> in the integral method. Assuming that isotropic elasticity theory is applicable, the stress tensor <σij> was calculated, and excellent agreement was found between the values determined with the ϕ integral and ψ-differential methods.

The following study is an evaluation of several different types of instrumentation available for use in powder x-ray diffraction work. The particular units used are those at the Dow Chemical Company x-ray diffraction lab. The variety of instrumentation allows analyses from routine phase identification to more specialized work such as low-angle x-ray diffraction of polymers and high-resolution analysis for cell parameter refinements.

The purpose of this work is to compare the relative capabilities of these different instruments under typical day-to-day operating conditions. While not a comprehensive study, the conclusions drawn should be applicable to powder x-ray diffraction in general.

Empirical algorithms for the treatment of interelement effects in x-ray fluorescence spectrometry are reviewed. It is recommended that the effects of tertiary x-ray emission be treated separately from those of x-ray absorption, and that standard reference materials of composition close to that of the specimen be used.

Calculations carried out to investigate the van Cittert iterative deconvolution method and the effects of random noise and truncation errors on its convergence behavior are presented. Gaussian functions are used for "both the true function W and the system, response function A. The model "observed" function S is generated from W and A. Both rms differences between the result of n iterations Wn and the true function, and between Wn*A and S are used to measure convergence. The effects of introducing errors can be measured against standards set by the convergence without such errors. These "no-error" calculations make use of true functions with widths from 2.0 to 0.67 times the response function width. The effects of random noise are investigated by adding noise to W*A before deconvolution. A small amount of random noise initially added builds up rapidly in amplitude during the iterative process and eventually dominates the rms difference calculations. To suppress the effects of random noise build-up; smoothing techniques are applied, the best of which involved smoothing both the noisy observed function, S, and the system response function, A, before deconvolution. The smoothing operation is thus taken as part of the measurement and. the divergence resulting from, the noise build-up is avoided. The results depend strongly upon, the -width of the smoothing function. Uhsymmetric system response functions, similar' to those encountered in soft x-ray appearance potential spectroscopy and in x-ray continuum, isochromat measurements, are used in investigations of truncation errors. Abrupt cut-offs of the model S and A functions before deconvolution result in the build-up of large fluctuations in W . These truncation errors become increasingly localized with continued iterations and make only minor contributions to the errors in Wn in the vicinity of the real peak if the truncations are made sufficiently far from the peak location. Alternatively, the truncation errors can be avoided by analytical continuation.